Digital Voltmeter Using An 8051 Microcontroller Computer Science Essay

Digital Voltmeter Using An 8051 Microcontroller Computer Science Essay A voltmeter finds its importance wherever voltage is to be measured. A  voltmeter  is an instrument used for measuring the  electrical potential  difference between two points in an electric circuit. Analog voltmeters move a pointer across a scale in proportion to the voltage of the circuit. General purpose analog voltmeters may have an accuracy of a few per cent of full scale, and are used with voltages from a fraction of a volt to several thousand volts. Digital voltmeters give a numerical display of voltage by use of analog to digital converter. Digital meters can be made with high accuracy, typically better than 1%. Specially calibrated test instruments have higher accuracies, with laboratory instruments capable of measuring to accuracies of a few parts per million. Meters using  amplifiers  can measure tiny voltages of micro-volts or less. Digital voltmeters (DVMs) are usually designed around a special type of  analog-to-digital converter  called an  integrating converter. Voltmeter accuracy is affected by many factors, including temperature and supply voltage variations. To ensure that a digital voltmeters reading is within the manufacturers specified tolerances, they should be periodically calibrated. Digital voltmeters necessarily have input amplifiers, and, like vacuum tube voltmeters, generally have a constant input resistance of 10 mega-ohms regardless of set measurement range. This project aims at building a Digital Voltmeter using an 8051 microcontroller. All the data accessed and processed by the microcontroller is the digital data. And thus, the usage of an analog-to-digital converter finds its necessity here. A standard analog-to-digital converter ADC0804 is used in the current project. The input voltage (which is the analog input) is restricted to be in the range of 0-15V. The processed data in the 8051 is used to drive a display output on a LCD display unit. The display is in the form of digits and is accurate to a value of one decimal. The input voltage is desired to be that of a DC voltage for steady observations of the voltage value on the LCD panel. Rather, if an AC input voltage is given at the input terminals, the output varies indefinitely as is the nature of AC voltage. Thus, the instantaneous value of the AC voltage is not steadily shown on the LCD panel. COMPONENTS Following is the entire set of the components used to build the Digital Voltmeter: Microcontroller, AT89S52 Analog-to-Digital Converter, ADC0804 161 LCD Oscillator circuit for the microcontroller 12MHz Crystal Capacitor 33pF Capacitors Voltage divider circuit/ Input terminals 200k, 100k Resistors 100nF Capacitor ADC Clock Circuit 10k Resistor 150pF Capacitor 100k Potentiometer (to adjust the back-light of the LCD) Description of the Components used Microcontroller, AT89S52 Æ’Â   The AT89S51 is a low-power, high-performance CMOS 8-bit microcontroller with 4K bytes of In-System Programmable Flash memory. The device is manufactured using Atmels high-density non-volatile memory technology and is compatible with the industry-standard 80C51 instruction set and pin-out. The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional non-volatile memory programmer. By combining a versatile 8-bit CPU with In-System Programmable Flash on a monolithic chip, the Atmel AT89S51 is a powerful microcontroller which provides a highly-flexible and cost-effective solution to many embedded control applications. The AT89S51 provides the following standard features: 4K bytes of Flash, 128 bytes of RAM, 32 I/O lines, Watchdog timer, two data pointers, two 16-bit timer/counters, a five-vector two-level interrupt architecture, a full duplex serial port, on-chip oscillator, and clock circuitry. In addition, the AT89S51 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. The Idle mode stops the CPU while allowing the RAM, timer/counters, serial port, and interrupt system to continue functioning. The Power-down mode saves the RAM con-tents but freezes the oscillator, disabling all other chip functions until the next external interrupt or hardware reset. Pin configuration of the AT89S52 is as follows: 40-Lead PDIP VCC Supply voltage. GND Ground. Port 0 Port 0 is an 8-bit open drain bi-directional I/O port. As an output port, each pin can sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as high-impedance inputs. Port 0 can also be configured to be the multiplexed low-order address/data bus during accesses to external program and data memory. In this mode, P0 has internal pull-ups. Port 0 also receives the code bytes during Flash programming and outputs the code bytes during program verification. External pull-ups are required during program verification. Port 1 Port 1 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 1 output buffers can sink/source four TTL inputs. When 1s are written to Port 1 pins, they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 1 pins that are externally being pulled low will source current (IIL) because of the internal pull-ups. Port 1 also receives the low-order address bytes during Flash programming and verification. P1.5 MOSI (used for In-System Programming) P1.6 MISO (used for In-System Programming) P1.7 SCK (used for In-System Programming) Port 2 Port 2 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 2 output buffers can sink/source four TTL inputs. When 1s are written to Port 2 pins, they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 2 pins that are externally being pulled low will source current (IIL) because of the internal pull-ups. Port 2 emits the high-order address byte during fetches from external program memory and during accesses to external data memory that use 16-bit addresses (MOVX @ DPTR). In this application, Port 2 uses strong internal pull-ups when emitting 1s. During accesses to external data memory that use 8-bit addresses (MOVX @ RI), Port 2 emits the contents of the P2 Special Function Register. Port 2 also receives the high-order address bits and some control signals during Flash programming and verification. Port 3 Port 3 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 3 output buffers can sink/source four TTL inputs. When 1s are written to Port 3 pins, they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low will source current (IIL) because of the pull-ups. Port 3 receives some control signals for Flash programming and verification. Port 3 also serves the functions of various special features of the AT89S51, as shown in the following table. Alternate functions of port 3, P3.0 RXD (serial input port) P3.1 TXD (serial output port) P3.2 INT0 (external interrupt 0) P3.3 INT1 (external interrupt 1) P3.4 T0 (timer 0 external input) P3.5 T1 (timer 1 external input) P3.6 WR (external data memory write strobe) P3.7 RD (external data memory read strobe) RST Reset input. A high on this pin for two machine cycles while the oscillator is running resets the device. This pin drives High for 98 oscillator periods after the Watchdog times out. The DIS-RTO bit in SFR AUXR (address 8EH) can be used to disable this feature. In the default state of bit DISRTO, the RESET HIGH out feature is enabled. ALE/PROG Address Latch Enable (ALE) is an output pulse for latching the low byte of the address during accesses to external memory. This pin is also the program pulse input (PROG) during Flash programming. In normal operation, ALE is emitted at a constant rate of 1/6 the oscillator frequency and may be used for external timing or clocking purposes. Note, however, that one ALE pulse is skipped during each access to external data memory. If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the bit set, ALE is active only during a MOVX or MOVC instruction. Otherwise, the pin is weakly pulled high. Setting the ALE-disable bit has no effect if the microcontroller is in external execution mode. PSEN Program Store Enable (PSEN) is the read strobe to external program memory. When the AT89S51 is executing code from external program memory, PSEN is activated twice each machine cycle, except that two PSEN activations are skipped during each access to external data memory. EA/VPP External Access Enable. EA must be strapped to GND in order to enable the device to fetch code from external program memory locations starting at 0000H up to FFFFH. Note, however, that if lock bit 1 is programmed, EA will be internally latched on reset. EA should be strapped to VCC for internal program executions. This pin also receives the 12-volt programming enable voltage (VPP) during Flash programming. XTAL1 Input to the inverting oscillator amplifier and input to the internal clock operating circuit. XTAL2 Output from the inverting oscillator amplifier. Memory Organisation, Program Memory: If the EA pin is connected to GND, all program fetches are directed to external memory. On the AT89S51, if EA is connected to VCC, program fetches to addresses 0000H through FFFH are directed to internal memory and fetches to addresses 1000H through FFFFH are directed to external memory. Data Memory: The AT89S51 implements 128 bytes of on-chip RAM. The 128 bytes are accessible via direct and indirect addressing modes. Stack operations are examples of indirect addressing, so the 128 bytes of data RAM are available as stack space. Interrupts: The AT89S51 has a total of five interrupt vectors: two external interrupts (INT0 and INT1), two timer interrupts (Timers 0 and 1), and the serial port interrupt. Each of these interrupt sources can be individually enabled or disabled by setting or clearing a bit in Special Function Register IE. IE also contains a global disable bit, EA, which disables all interrupts at once. The Timer 0 and Timer 1 flags, TF0 and TF1, are set at S5P2 of the cycle in which the timers overflow. The values are then polled by the circuitry in the next cycle. ADC0804 Æ’Â   The ADC080X family are CMOS 8-Bit, successive approximation A/D converters which use a modified potentiometric ladder and are designed to operate with the 8080A control bus via three-state outputs. These converters appear to the processor as memory locations or I/O ports, and hence no interfacing logic is required. The differential analog voltage input has good common-mode-rejection and permits offsetting the analog zero input voltage value. In addition, the voltage reference input can be adjusted to a low encoding any smaller analog voltage span to the full 8 bits of resolution. The functional diagram of the ADC080X series of A/D converters operates on the successive approximation principle. Analog switches are closed sequentially by successive-approximation logic until the analog differential input voltage [VlN(+) VlN(-)] matches a voltage derived from a tapped resistor string across the reference voltage. The most significant bit is tested first and after 8 comparisons (64 clock cycles), an 8- bit binary code (1111 1111 = full scale) is transferred to an output latch. The normal operation proceeds as follows. On the high-to-low transition of the WR input, the internal SAR latches and the shift-register stages are reset, and the INTR output will be set high. As long as the CS input and WR input remain low, the A/D will remain in a reset state. Conversion will start from 1 to 8 clock periods after at least one of these inputs makes a low to high transition. After the requisite number of clock pulses to complete the conversion, the INTR pin will make a high- to-low transition. This can be used to interrupt a processor, or otherwise signal the availability of a new conversion. A RD operation (with CS low) will clear the INTR line high again. The device may be operated in the free-running mode connecting INTR to the WR input with CS = 0. To ensure start-up under all possible conditions, an external WR pulse is required during the first power-up cycle. A conversion in process can be interrupted by issuing a second start command. Digital Operation The converter is started by having CS and WR simultaneously low. This sets the start flip-flop (F/F) and the resulting 1 level resets the 8-bit shift register, resets the Interrupt (INTR) F/F and inputs a 1 to the D flip-flop, DFF1, which is at the input end of the 8-bit shift register. Internal clock signals then transfer this 1 to the Q output of DFF1. The AND gate, G1, combines this 1 output with a clock signal to provide a reset signal to the start F/F. If the set signal is no longer present (either WR or CS is a 1), the start F/F is reset and the 8-bit shift register then can have the 1 clocked in, which starts the conversion process. If the set signal were to still be present, this reset pulse would have no effect (both outputs of the start F/F would be at a 1 level) and the 8-bit shift register would continue to be held in the reset mode. This allows for asynchronous or wide CS and WR signals. After the 1 is clocked through the 8-bit shift register (which completes the SAR ope ration) it appears as the input to DFF2. As soon as this 1 is output from the shift register, the AND gate, G2, causes the new digital word to transfer to the Three-State output latches. When DFF2 is subsequently clocked, the Q output makes a high-to-low transition which causes the INTR F/F to set. An inverting buffer then supplies the INTR output signal. When data is to be read, the combination of both CS and RD being low will cause the INTR F/F to be reset and the three state output latches will be enabled to provide the 8-bit digital outputs. Digital Control Inputs The digital control inputs (CS, RD, and WR) meet standard TTL logic voltage levels. These signals are essentially equivalent to the standard A/D Start and Output Enable control signals, and are active low to allow an easy interface to microprocessor control busses. For non-microprocessor based applications, the CS input (pin 1) can be grounded and the standard A/D Start function obtained by an active low pulse at the WR input (pin 3). The Output Enable function is achieved by an active low pulse at the RD input (pin 2). Analog Operation The analog comparisons are performed by a capacitive charge summing circuit. Three capacitors (with precise ratioed values) share a common node with the input to an autozeroed comparator. The input capacitor is switched between VlN(+) and VlN(-), while two ratioed reference capacitors are switched between taps on the reference voltage divider string. The net charge corresponds to the weighted difference between the input and the current total value set by the successive approximation register. A correction is made to offset the comparison by 1/2 LSB. Analog Differential Voltage Inputs and Common- Mode Rejection This A/D gains considerable applications flexibility from the analog differential voltage input. The VlN(-) input (pin 7) can be used to automatically subtract a fixed voltage value from the input reading (tare correction). This is also useful in 4mA 20mA current loop conversion. In addition, common-mode noise can be reduced by use of the differential input. The time interval between sampling VIN(+) and VlN(-) is 41/2 clock periods. There is maximum error voltage due to this slight time difference between the input voltage samples. The allowed range of analog input voltage usually places more severe restrictions on input common-mode voltage levels than this. An analog input voltage with a reduced span and a relatively large zero offset can be easily handled by making use of the differential input. Analog Input Current The internal switching action causes displacement currents to flow at the analog inputs. The voltage on the on-chip capacitance to ground is switched through the analog differential input voltage, resulting in proportional currents entering the VIN(+) input and leaving the VIN(-) input. These current transients occur at the leading edge of the internal clocks. They rapidly decay and do not inherently cause errors as the on-chip comparator is strobed at the end of the clock period. Input Bypass Capacitors Bypass capacitors at the inputs will average these charges and cause a DC current to flow through the output resistances of the analog signal sources. This charge pumping action is worse for continuous conversions with the VIN(+) input voltage at full scale. For a 640kHz clock frequency with the VIN(+) input at 5V, this DC current is at a maximum of approximately 5uA. Therefore, bypass capacitors should not be used at the analog inputs or the VREF/2 pin for high resistance sources (>1kOhm.) If input bypass capacitors are necessary for noise filtering and high source resistance is desirable to minimize capacitor size, the effects of the voltage drop across this input resistance, due to the average value of the input current, can be compensated by a full scale adjustment while the given source resistor and input bypass capacitor are both in place. This is possible because the average value of the input current is a precise linear function of the differential input voltage at a constant conversion rate. Input Source Resistance Large values of source resistance where an input bypass capacitor is not used will not cause errors since the input currents settle out prior to the comparison time. If a low-pass filter is required in the system, use a low-value series resistor for a passive RC section or add an op amp RC active low-pass filter. For low-source-resistance applications, a 0.1uF bypass capacitor at the inputs will minimize EMI due to the series lead inductance of a long wire. A 100Ohm series resistor can be used to isolate this capacitor (both the R and C are placed outside the feedback loop) from the output of an op amp, if used. Stray Pickup The leads to the analog inputs (pins 6 and 7) should be kept as short as possible to minimize stray signal pickup (EMI). Both EMI and undesired digital-clock coupling to these inputs can cause system errors. The source resistance for these inputs should, in general, be kept below 5kÃŽÂ ©. Larger values of source resistance can cause undesired signal pickup. Input bypass capacitors, placed from the analog inputs to ground, will eliminate this pickup but can create analog scale errors as these capacitors will average the transient input switching currents of the A/D (see Analog Input Current). This scale error depends on both a large source resistance and the use of an input bypass capacitor. This error can be compensated by a full scale adjustment of the A/D (see Full Scale Adjustment) with the source resistance and input bypass capacitor in place, and the desired conversion rate. Reference Voltage Span Adjust For maximum application flexibility, these A/Ds have been designed to accommodate a 5V, 2.5V or an adjusted voltage reference. This has been achieved in the design of the IC. Notice that the reference voltage for the IC is either 1/2 of the voltage which is applied to the V+ supply pin, or is equal to the voltage which is externally forced at the VREF/2 pin. This allows for a pseudo-ratiometric voltage reference using, for the V+ supply, a 5V reference voltage. Alternatively, a voltage less than 2.5V can be applied to the VREF/2 input. The internal gain to the VREF/2 input is 2 to allow this factor of 2 reduction in the reference voltage. Zero Error The zero of the A/D does not require adjustment. If the minimum analog input voltage value, VlN(MlN), is not ground, a zero offset can be done. The converter can be made to output 0000 0000 digital code for this minimum input voltage by biasing the A/D VIN(-) input at this VlN(MlN) value. This utilizes the differential mode operation of the A/D. The zero error of the A/D converter relates to the location of the first riser of the transfer function and can be measured by grounding the VIN(-) input and applying a small magnitude positive voltage to the VIN(+) input. Zero error is the difference between the actual DC input voltage which is necessary to just cause an output digital code transition from 0000 0000 to 0000 0001 and the ideal 1/2 LSB value (1/2 LSB = 9.8mV for VREF/2 = 2.500V). Full Scale Adjust The full scale adjustment can be made by applying a differential input voltage which is 11/2 LSB down from the desired analog full scale voltage range and then adjusting the magnitude of the VREF/2 input (pin 9) for a digital output code which is just changing from 1111 1110 to 1111 1111. When offsetting the zero and using a span-adjusted VREF/2 voltage, the full scale adjustment is made by inputting VMlN to the VIN(-) input of the A/D and applying a voltage to the VIN(+) input. Clocking Option The clock for the A/D can be derived from an external source such as the CPU clock or an external RC network can be added to provide self-clocking. The CLK IN (pin 4) makes use of a Schmitt trigger. Heavy capacitive or DC loading of the CLK R pin should be avoided as this will disturb normal converter operation. Loads less than 50pF, such as driving up to 7 A/D converter clock inputs from a single CLK R pin of 1 converter, are allowed. For larger clock line loading, a CMOS or low power TTL buffer or PNP input logic should be used to minimize the loading on the CLK R pin (do not use a standard TTL buffer). Restart During a Conversion If the A/D is restarted (CS and WR go low and return high) during a conversion, the converter is reset and a new conversion is started. The output data latch is not updated if the conversion in progress is not completed. The data from the previous conversion remain in this latch. Continuous Conversions In this application, the CS input is grounded and the WR input is tied to the INTR output. This WR and INTR node should be momentarily forced to logic low following a power-up cycle to insure circuit operation. Interfacing the Microcontroller Interfacing the ADC0804 with 8051 Æ’Â   As shown in the typica circuit, ADC0804 can be interfaced with any microcontroller. A minimum of 11 pins are required to interface the ADC0804, eight for data pins and 3 for control pins. As shown in the typical circuit the chip select pin can be made low if you are not using the microcontroller port for any other  peripheral  (multiplexing). There is a  universal  rule to find out how to use an IC. All we need is the datasheet of the IC we are working with and a look at the  timing diagram  of the IC which shows how to send the data, which signal to assert and at what time  the signal  should be made high or low, etc. Timing Diagrams, Pin Description 1.  Ã‚  CS, Chip Select: This is an active low pin and used to activate the ADC0804. 2.  Ã‚  RD, Read: This is an input pin and active low. After converting the analog data, the ADC stores the result in an internal register. This pin is used to get the data out of the ADC 0804 chip. When CS=0 high to low pulse is given to this pin, the digital output is shown on the pins D0-D7. 3.  Ã‚  WR, Write: This is an input pin and active low. This is used to instruct the ADC to start the conversion process. If CS=0 and WR makes a low to high transition, the ADC starts the conversion process. 4.  Ã‚  CLK IN, Clock IN: This is an input pin connected to an external clock source. 5.  Ã‚  INTR, Interrupt: This is an active low output pin. This pin goes low when the conversion is over. 6.   Vin+ : Analog Input . 7.   Vin- : Analog Input. Connected to ground. 8.  Ã‚  AGND: Analog Ground. 9.  Ã‚  Vref/2: This pin is used to set the reference voltage. If this is not connected the default reference voltage is 5V. In some application it is required to reduce the step size. This can be done by using this pin. 10.   DGND: Digital Ground. 11-18. Output Data Bits (D7-D0). 19. CLKR: Clock Reset. 20. Vcc: Positive Supply The above timing diagrams are from ADC0804 datasheet. The first diagram shows how to start a conversion. Also you can see which signals are to be asserted and at what time to start a conversion. So looking into the timing diagram  we note down the steps or say the order in which signals are to be asserted to start a conversion of ADC. As we have decided to make Chip select pin as low so we need not to bother about the CS signal in the  timing diagram. Below steps are for starting an ADC conversion. I am also including CS signal to give you a clear picture. While programming we will not use this signal. Make chip select (CS) signal low. Make write (WR) signal low. Make chip select (CS) high. Wait for INTR pin to go low (means conversion ends). Once the conversion in ADC is done, the data is available in the output latch of the ADC. Looking at the second diagram, which shows the  timing diagram  of  how to read  the converted value from the output latch of the ADC, data of the new conversion is only available for reading after ADC0804 made INTR pin low or say when the conversion is over. Below are the steps to read output from the ADC0804. Make chip select (CS) pin low. Make read (RD) signal low. Read the data from port where ADC is connected. Make read (RD) signal high. Make chip select (CS) high. Interfacing the LCD with 8051 Æ’Â   Pin Information of LCD: Pin No Name Description 1 Vss Ground 2 Vdd +5V 3 Vee Contrast Adjustment -2V to -5V 4 RS Register Select 5 RW 1 -Read , 0- Write 6 E Enable Strobe 7 D0 Data Line 8 D1 Data Line 9 D2 Data Line 10 D3 Data Line 11 D4 Data Line 12 D5 Data Line 13 D6 Data Line 14 D7 Data Line 15 LED+ Backlit LED +V   Vdd (Optional signal) 16 LED- Backlit LED -V   Vss (Optional signal) Algorithm to send data to LCD: 1.Make R/W low 2.Make RS=0 ;if data byte is command RS=1 ;if data byte is data (ASCII value) 3.Place data byte on data register 4.Pulse E (HIGH to LOW) 5.Repeat the steps to send another data byte LCD Initialization: Proper working of LCD depend on the how the LCD is initialized. We have to send few command bytes to initialize the LCD. Simple steps to initialize the LCD Specify function set: Send  38H  for 8-bit, double line and 57 dot character format. Display On-Off control: Send  0FH  for display and blink cursor on. Entry mode set: Send  06H  for cursor in increment position and shift is invisible. Clear display: Send  01H  to clear display and return cursor to home position. Writing software: The LCD module is an intelligent component. We communicate to LCD module by sending commands from microcontroller. To write data to LCD module separate sequence is followed for 4 bit and 8 bit mode. Writing command for 8 Bit mode: Write 8 bit data on D0-D7 Generate strobe by taking EN from high to low Writing command for 4 Bit mode: Write 4 bit data (upper nibble) on D4-D7 Generate strobe by taking EN from high to low Write 4 bit data (lower nibble) on D4-D7 Generate strobe by taking EN from high to low LCD Commands:   Instruction RS RW D7 D6 D5 D4 D3 D2 D1 D0 Description NOP 0 0 0 0 0 0 0 0 0 0 No Operation Clear Display 0 0 0 0 0 0 0 0 0 1 Clear Display and Address counter = 0 Cursor Home 0 0 0 0 0 0 0 0 1 x Address counter = 0 Entry mode set 0 0 0 0 0 0 0 1 I/D S Set cursor direction(I/D) and auto display shift (S) Display Control 0 0 0 0 0 0 1 D C B Turn display (D) and cursor (C) ON/OFF. Set cursor blinking(B) Cursor/ Display shift 0 0 0 0 0 1 S R/L x x Shift display/cursor (S), specify direction (R/L) Function set 0 0 0 0 1 DL N F x x Set Interface data width (DL), number of display lines (N), character font (F) Set CGRAM Address 0 0 0 1 Set CGRAM address (D0-D5), CGRAM data is sent after this command Set DDRAM Address 0 0 1 Set DDRAM address (D0-D6), DDRAM data is sent after this command Busy Flag and Address 0 1 BF Read busy flag (BF) and address counter(D0-D6) Write Data 1 0 Write data (D0-D7) into DDRAM/CGRAM Read Data 1 1 Read data (D0-D7) from DDRAM/CGRAM Legends used in table:- I/D:  Ã‚  Ã‚  Ã‚  Ã‚  1- Increment, 0- Decrement S:  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  1- Auto Display shift, 0 No display shift D:  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  1- Display ON, 0 Display OFF C:  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  1- Cursor ON, 0- Cursor OFF B:  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  1- Cursor blinking ON, 0 Cursor blinking OFF S:  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  1- Display Shift, 0 -Cursor move R/L:  Ã‚  Ã‚  Ã‚  1- Shift right, 0- Shift left DL:  Ã‚  Ã‚  Ã‚  Ã‚  1- 8 bit interface, 0- 4 bit interface N:  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  1- 2 lines, 0- 1 line F:  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  1- 5X10 dots font, 0- 5X7 dots f

Free College Admissions Essays: Leadership Qualities :: College Admissions Essays

Leadership Qualities  Ã‚   The most meaningful and challenging experiences in my life have been through sports and the 4-H club. They have instilled the values of perseverance, confidence, and teamwork within me. I feel that my peers and others could learn valuable life lessons through participating in these organizations. They are not just clubs, but a guiding light for life. For example in sports I have had the opportunity to play on both losing and winning teams. This has given me a different perspective of looking at things. I now realize that even if you fail or lose that is no reason to give up, you still have to get right back up. Just realize your mistakes and errors. Then come back the next time, mentally and physically, ready to meet the challenge. To often in life youth and adults alike fail at something and automatically think that they cannot do it, and give up. Instead of just pushing themselves to run another lap, lift another set, study for another hour, or learn another theorem. Imagine a worl d if the early American settlers had given in to the British, if the North had given in to the South after the first loss of the civil war, or if Michael Jordan had given up after being cut from the team in high school. People just need to learn to have perseverance and believe in themselves. 4-H has been a series of stepping-stones for me. When I first started out at age four I was shy and afraid to do things that I had not done before, but now I have blossomed into a confident and outgoing young man. I no longer fear getting up in front of large groups and speaking because of the experiences I've had in public speaking events. In addition, 4-H has given me the chance to develop myself as a leader. Over the years I have held various leadership positions on the club, county, and district levels. Also, 4-H has given me the chance to go into the community and help people by leading youth in workshops, assisting the handicap and elderly, and also learn from what others have to teach. I n both of these organizations I learned the need for teamwork. For example last year my football team went 0-11 and the main reason because of that was we were not a team.

Weber’s social psychology and tonnies gemeinschaft

Weber was one of the first modern thinkers who attempted to evolve a rational perspective in understanding social phenomenon. He perpetually fostered the theory of objectivity in all human action. Thus he often states that in all sciences where human action is involved it is essential that those occurrences which are without subjective meaning should be given priority. (Weber, 1994). He frequently contended that without the basic form of a thing, its physical quantity, it had literally no meaning. He emphasized that from birth to mortality it is facts that dictated human action. Weber went to the extent of indicating that even those facts which were psycho physical or social including reactions of individuals should be understood by taking into account the data within. Thus while Weber disavowed the use of psychological methods in society, there is an implicit social psychology in Weber’s work.   This is evident through an in depth analysis of his works which indicate many hints of social psychology implicit in the subjective understanding of phenomenon, in the functioning of public bodies and the concept of charisma. The first indication of the same is his distinguishing understanding of observable and non observable phenomenon. While understanding of observable phenomenon is easier, he indicates that there is another type of recognition that is explanatory in nature. This comprises of actions and emotions that are displayed by individuals in society over incidents which cause rage, joy, jealousy, pride and so on, in which the motives are not rationally explainable and for which a subjective meaning for the action may have to be sought as an intended meaning. Thus for correct interpretation of an event or a fact he denotes that it is essential to understand the covert motive behind that act or event and link one to the other. The motive is the subjective part of the meaning which can be found not just in the factual display but would be in the psycho social content of the message that each is attempting to convey. The social psychological context of Weber’s views is further crystallized when he explains the functioning of public bodies. These need to be treated as individuals when they are performing normal cognitive purposes such as juristic and should have the same rights and duties. In subjective interpretation these are considered as sociological formations, the resultants of collectivities arising from constructs from other disciplines. (Weber, 2005). Thus these organizations become the epitome of social action of individual persons in collectivity and the psychological influence cannot be undermined in their actions. The final interpretation of the impact of psychology on sociology in the works of Weber is found in his concept of charisma, which he states as psychic contagion and creates a number of social processes which are understood only in terms of subjectivities in small fragments of transfer from biological interpretation. This is a minor concession that Weber attempts to make towards accepting non scientific phenomenon as a basis for understanding human social behavior. Toennies considered that change is an intrinsic part of human nature. Change comes from the two facets of human nature one that is dialectical and the other that is contradictory. Thus human evolution as per Toennies has passed through various stages of individualistic and communal feelings which are shared with others. Individualistic strain is stronger in trade and politics and is the lowest in science. These are the concepts of evolution aptly summarized in two German words of gemeinschaft and gesellschaft.   (Toennies, 1954). Toennies society evolved from a social context in which human beings were enemies of each other and extensive law was essential to preserve order. Gradually communal life gained primacy and order overcome anarchy. However Tonnies indicates that this order in turn led more people to come together with the aim of gaining prosperity which is again as per him a sign of the class struggle which destroys society that is being transformed. Thus the cycle seems to continue interminably. The essence of Tonnies process of evolution of Western civilization lay in the two phases of being communal to being associative. The Gemeinschaft or communal in German was characterized by geographically isolated communes where all members virtually appeared to of the same stock, lived by tradition and maintained consanguine ties within the families. Labor was cast on pre industrial mode without any division and there was greater emphasis on primary relationships based on the importance of status and a respect for sacredness. This phase lasted till the entry into the industrial age when from small commune’s mass heterogeneous groupings of people emerged. This was the associative or Gesellschaft mode of social living.  Ã‚   There was greater geographic mobility as more and more people mixed with each other, tradition declined and heterogeneous relationships developed. Conjugal ties were greatly emphasized during this period and there was a division of labor. Status was not bestowed on people due to birth but due to their own achievements. There was greater dependence on secondary relationships and building a secular society. These two stages in which human societies evolved are indicative of the industrial and the post industrial World. Toennies theme was further elaborated by Emile Durkheim who indicated how forms of Gemeinschaft and Gesellschaft emerged. The homogeneity and lack of division of labor were attributed to the pre industrial society. The cohesiveness of tribalism to Tonnies was a mechanistic mode of congruity. Collective conscience and representations through means such as common flag were another form of community feeling and provide indication how it developed over the years. However as society grew, an heterogeneous sense of bonding developed into what Tonnies has described as the Gesellschaft in which more and more relationships were secondary and impersonal. In some forms slavery and feudalism is a part of the community that existed in the pre industrial age and was only eliminated after the industrial age came to dominate the human activity spectrum. The industrial capitalist society also greatly revolutionized social conditions as the capitalist forces attempted to expand beyond their boundaries in search of trade so did the assimilative values were transferred between different societies which mingled with each other. Reference: 1.Toennies, F. (1957) Community and Society. East Lansing, MI. 2.Weber, Max. (1999). Sociological Writings. Edited by Wolf Heydebrand, published in 1994 by Continuum. Transcribed: by Andy Blunden in 1998, proofed and corrected 1999. 3.– (2005). The Protestant Ethic and the Spirit of Capitalism. 1905. Translated by   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   Talcott Parsons and Anthony Giddens. London : Unwin Hyman.      

The Slavery Of The African Slave Trade - 1280 Words

British slave trading begun in the late sixteenth century and grew remarkably during the seventeenth and eighteenth centuries. As a woman in society, she faced challenges herself; however, she addressed the humanity of slaves as human beings and not by the color of their skin. She believed that â€Å"non whites† were equal to â€Å"whites† and deserved the same human rights. She wrote her famous piece, â€Å"Slavery, a Poem† during the abolitionist movement to persuade others to partake in the anti-slavery campaign. Hannah More condemns British slavery in â€Å"Slavery, a Poem† by advocating for women, religion, and depicting the inhumane treatment of Africans in order to promote human rights. Hannah More is one of the most influential female writers who represented the Society for Effecting the Abolition of the African Slave Trade (Ferguson). After contributing to the founding of the Abolition Society in 1788, she published â€Å"Slavery, a Poem† (Mellor). During the time, writers would demean Britain’s appearance by referencing the country as â€Å"disgusting, atrocities, dividing families, etc.† (Elliot). Hannah More does criticize the slave trade, but she also tries to appeal to the pro-slavery audience, in order to change the current legislation. By doing so, she addresses the â€Å"Great Chain of Being,† where men are categorized higher than women and slaves even lower. Basically, she felt like society was constructed to benefit the white race (Ferguson): â€Å"Whene’er to Afric’s shores I turn my eyes,Show MoreRelatedThe Slavery Of African Slave Trade1039 Words   |  5 Pagesthe practiced slavery that took place in Africa . Slavery included stripping humans of their identities and classifying them as property, forcing them to obey their masters. The slaves had no rights and humanity had fled their thinking. Some even claimed slaves to be aliens even though they were not. Slave’s masters could do what ever they pleased with the slaves including, making them do their dirty work, striking them whenever they pleased and abusing their slave sexually. The slave had no defenseRead MoreSlavery And The African Slave Trade1449 Words   |  6 PagesWhen I think of the African slave trade, I realize that over 10 million people were removed from that continent in less than 500 years. Some scholars believe it may be as large a number as 20 million. I would like to pose a few questions and attempt to answer them in this collection of writings and opinions. The evidence and historical documents will show some of the economic and social impacts the Slave Trade had on the African continent. Slavery has been around for the vast majority of human historyRead MoreAfrican Slavery And The Slave Trade Essay1795 Words   |  8 PagesIntroduction Slavery is the legalized economic activity under which people, especially the natives of a land, are treated as property by colonizers like the Spanish. Slavery was a system that lasted for many years before it was abolished and the Africans as well as the Indians went through a lot of suffering upon the hands of their masters. The slaves were meant to perform duties such as cultivation of the plantations, domestic chores and even mining activities and were on the constant watch ofRead MoreThe European Slave Trade And Intra African Slavery1511 Words   |  7 PagesThe European slave trade and intra-African slavery began with different intentions and goals held in mind. Although, they also shared similar aspects and ideals shown through how they functioned and were run. Intra- African slavery began before the European slave trade came to exist; this unpopular fact shows the beginning of such a gruesome and detrimental act began by the people of Africa, which, later in time, is what fuels and strengthens the European slave trade. African slaves were once capturedRead MoreThe Impact of Slavery on African Society Essay1149 Words   |  5 PagesThe Impact of Slavery on African Society Slavery has played a strong role in African society from as early as prehistoric times, continuing to the modern era. Early slavery within Africa was a common practice in many societies, and was very central to the country’s economy. Beginning around the 7th century, two groups of non-African slave traders significantly altered the traditional African forms of slavery that had been practiced in the past. Native Africans were now being forced to leave theRead MoreSlavery And Its Effects On Slavery1520 Words   |  7 Pages Slavery is a system under which people are treated as property. The people in the time of Renaissance enslaved people to use them as labourers and or do other types of labour. Should that be the reason of our change of knowledge towards slaves and how we perceive them. A slave is a human being or an â€Å"animal† (The Mission) classified as property and who is forced to work for nothing (The Abolition of Slavery Project, October 11, 2014). The word Slavery has a bitter taste flowing off the tongue.Read MoreAfrican American Slavery And The New World Essay1453 Words   |  6 Pagesfortunate which at the time beingbwere africans. These laborers brung unimaginable wealth to empires but were treated as objects and their entire life were in the hands of their buyers. Its not clear exactly how and why something so cruel such as taking someones like and belittling it for labor reasons could have happened for so long. With my class notes and leads from the textbook it seems thst the forces tgat best explain the emergence of african American slavery in the new world colonies of WesternRead MoreLEQ1206 Words   |  5 Pagestime period prior to the development of the Atlantic slave trade and the time period right after its introduction and assess the impact of its emergence. To what extent did African slavery change American society? You may want to consider social, economic, and geographical. Prior to the Atlantic slave trade, the arable land along the South Atlantic seaboard were owned by wealth landowners and farmed primarily by either Native American slaves or white indentured servants. Beginning in the late 16thRead MoreEssay on The Atlantic Slave Trade921 Words   |  4 PagesThe Atlantic Slave Trade The changes in African life during the slave trade era form an important element in the economic and technological development of Africa. Although the Atlantic slave trade had a negative effect on both the economy and technology, it is important to understand that slavery was not a new concept to Africa. In fact, internal slavery existed in Africa for many years. Slaves included war captives, the kidnapped, adulterers, and other criminals and outcasts. HoweverRead MoreEssay on Trans Atlantic Slave Trade1105 Words   |  5 PagesMarch 7, 2006 Trans Atlantic Slave Trade Slavery originated from Africa after the Bantu migrations spread agricultural to all parts of the continent. Africans would buy slaves to enlarge their families and have more power. Also, they would buy slaves in order to sell them to make a profit. It then spread out from Africa to Portugal and was said, it is estimated that during the four and a half centuries of the trans-Atlantic slave trade, Portugal was responsible for transporting