This programmer was designed in view of to be flexible, economical and easy to built, the programmer hardware utilizes the standard TTL series parts and no special components are used. The programmer is interfaced with the PC parallel port and there is no special requirement for the PC parallel port, so the older computers can also be used with this programmer.
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The programmer software supports the following Atmel devices
AT89C51 AT89C1051
AT89C52 AT89C1051U
AT89C55 AT89C2051
AT89S53 AT89C4051
AT89S8252
AT89C55WD
Note: For 20 pin devices a simple interface adapter is required.
The AT89C55WD has been included for testing purpose.
Figure 1 shows the circuit diagram of the Flash Programmer, the programmer is interfaced with the standard parallel port of the PC. As shown in the diagram U1 is used to control the data flow between controller and the PC, U3 latched the low order address byte and U4 latched the high order address byte, while U2 is used to generate the control signals for micro controller to be programmed. The power supply section uses U6 to generate the logic 5V supply while the U5 is used to provide the programming supply voltage to controller. The power to the circuit is provided by a wall adapter of 15 to 18V output, normally a 15V type adapter will provide a 19~20V output voltage. As shown in the diagram the crystal X1 can be replaced by a resonator in that case capacitors C4 and C5 are not required, the pcb has the provision for both type of devices.
For the adjustment of P1 and P2 follow the steps shown below,
1. First adjust P1 to get the 12.75V at the output of LM317L regulator, make sure transistor T4 is off or
temporarily connect the T4...
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