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87C51 PROGRAMMER ADAPTER

by Noel Rios

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

Sometimes, understanding todayıs technology is easier when you understand the background of a certain part or technology. So, if youıre new to the 8051, letıs step back from todayıs cutting-edge technology and look at a building block from 8051 programming history.

The 8051 microcontroller is a versatile device. It has four I/O ports (some with dual functions), two timers, a serial port, and two external timers or interrupt sources. The EPROM version, or the 87C51 microcontroller, contains 4 KB of EPROM and 128 KB of RAM (see Figure 1).

Figure 1ıThe microcontroller contains an internal 4-KB EPROM, which can be programmed by the 87C51 Programmer Adapter. (Click here for figure)

Programming the 87C51 is easy if you have a dedicated or universal programmer. However, these devices are expensive. If you have an EPROM programmer, you can use the 87C51 programmer adapter to burn the internal EPROM, making the 87C51 appear as a 2732 EPROM. The 87C51 programmer adapter will work with CMOS versions and the EPROM programmer. This will allow you to vary the programming algorithm to quick pulse and the programming voltage to 12.75 V for the 2732 EPROM, or you can choose a 2732 EPROM with a V_PP of 12.75 V and an algorithm of quick pulse.

Equally important, because an EPROM programmer only provides signals for a true EPROM, some signals (such as what is needed to program the security bit of the 87C51) cannot be accomplished. However, you can read and burn the data to the 87C51 with this simple, inexpensive adapter. A crystal, logic IC, and some miscellaneous items are all that are needed to build this adapter.

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