I got a pair of old robot controller boards based on 8051. It could drive four DC motors through its two L293 H-Bridge drivers, a 16×2 character LCD, an RS232 port and plenty of IO pins.But it was based on an old 8051, and that could be the reason that someone discarded this board in a junkyard.
Nowadays the most commonly used microcontroller board is the Arduino. It has a huge open-source support and plenty of libraries , making it the favourite of millions. So it would be cool to power this old robot controller with an arduino capable controller. A quick search in my components box gave me a couple of Atmega 328. But it was having a 28 pin DIP package while the controller board has a 40 pin DIP. Somehow I have to get around this problem and plug an Atmega 328 into it. I thought of making a breakout board with my Atmega328 soldered to it and with berg strips to plug directly into the 40 pin DIP socket. Within minutes, I ended with something as below
The soldering was crude, I admit. The Atmega was uploaded with the arduino bootloader using my USBASP programmer. Connections of power supply pins, crystal oscillator pins, all available IO pins and UART pins of the Atmega was matched with the corresponding pins of 8051. The matching of UART pins made it possible to burn the Atmega using the DB9 serial port connector of the controller board, which I could use with my custom USB to serial converter . Finally the arduino powered controller was plugged into the board
Eventually I ended with a powerful robot controller board . when the LCD is inserted, it makes it hard to see the modification. So now don’t ever throw something out useless as it only adds to the e-waste , but make something useful out of it