Aim
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To divide the given signal frequency applied at P3.5 by a digital value as obtained from Port-0 and output the signal through one of the port pins (say P1.0), i.e. OUT PUT_FREQ = (INP_FREQ) / (PORT0*2) |
Components/Software |
- Atmel 89C51 micro controller
- 8051 simulator- win8051
- Universal SP3 Programmer
- Software to load the code into Universal SP3 Programmer
- Computer System with Windows operating system and RS 232 Cable
- +5V D.C Power Supply
- SPST switches-1
- Resistors-8.2k-1
- Capacitors-30pF-2, 10uF-1
- 10MHz crystal
- Signal Generator and CRO
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Procedure |
- Write the assembly code in win8051 simulator , compile it and check for errors
- Once the code is error free, run it and check the output.
- After checking the code in the simulator, the code (in .HEX format) was loaded into Atmel 89c51 microcontroller using Universal SP3 Programmer.
- Make connections as shown in the circuit diagram.
- Load some value into PORT0 by externally giving some digital input.
- Square wave of 0 to +5V is given to the Pin P3.5 (timer 1 external clock input.)
- Observe the signal at pin P1.0 in the CRO and ensure that it satisfies the formula (INP_FREQ)/(PORT0*2)
- Change the frequency of input square and observe the frequency of out put square wave and each time ensure that it satisfies the above formula. (OUT PUT_FREQ = (INP_FREQ) / (PORT0*2) )
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Method |
Timer-1 is used for dividing the input signal by a given number obtained from Port-0. |
Assembly Code |
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Observations |
Since input square wave is used as Timer 1 external clock input see the external clock requirements in the datasheet of Atm8051. |
Conclusion |
Input signal frequency was divided by the following formula and out put the signal through pin P1.0. |
OUT PUT_FREQ = (INP_FREQ) / (PORT0*2) |
Circuit Diagram |
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Fig 40.1 Circuit diagram for frequency divider experiment
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