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87C51 PROGRAMMER ADAPTER

by Noel Rios

Start ę Circuit Description ę Construction and Assembly ę Sources and PDF

CONSTRUCTION AND ASSEMBLY

The circuit is assembled with point-to-point wiring. The PCB used is a prototyping board. For socket 2, use a wire-wrapping socket, so that it can be plugged to the EPROM programmer. A zero insertion force (ZIF) socket is highly recommended for socket 1. Keep the crystal close to socket 1. Also, note that Schottky diodes (1N5818) must be used for D2 and D3, or the circuit will not function properly. Pin 24 of socket 2 is the V_cc. Do not forget to connect R1, resistor pack 1, pin 1, and pin 14 of U1 (74LS86) to pin 24. Also, remember to connect pin 7 of U1 to pin 12 of socket 2. Equally important, place socket 2 of the PCB close to the edge so that the PCB will not cover the lever of the EPROM programmeręs ZIF socket (see Photo 1).

Photo 1ęThe 87C51 Programmer Adapter was constructed using point-to-point wiring. A zero insertion force socket for socket 1 is recommended if one is available. Note that with socket 2, the wire wrap socket is close to the edge so that the PCB will not block the EPROM programmeręs ZIF socket lever.

In addition, connect pin 40 of socket 1 to pin 24 of socket 2. Also, connect pin 20 of socket 1 to pin 12 of socket 2. These connections will provide power to the 74LS86 and to the inserted 87C51.

USING THE 87C51

To use the programmer, plug the 87C51 programming adapter to the EPROM programmer socket. Usually, the socket should align with the ground. Use an EPROM programmer where the programming parameters for the 2732 EPROM can be altered. The correct parameters are 12.75 for the V_PP and quick pulse algorithm, as shown in Figure 2. You also can use an EPROM programmer, for which you can choose a 2732 with the correct programming parameters. If you cannot select an EPROM with the correct parameters or set the proper programming parameters, do not use it. It will damage the 87C51 microcontroller.

I tested the 87C51 programming adapter with Philips 87C51 and Intel 87C51 microcontrollers. The circuit was also tested with only the CMOS version of the microcontroller. It will not work with the NMOS version.

The 87C51 programmer adapter is good for programming Philips and Intel 87C51 microcontrollers. With it, you can start building and designing 87C51-based projects without the need for expensive universal device programmers. The circuit is straightforward and can be improved by adding a voltage regulator to handle 21 V, but the quick pulse algorithm must be chosen for proper programming. The circuit provides a simple idea for programming certain microcontrollers and can be adapted to other brands of microcontrollers, once the proper logic level conditions for pins are met.

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