Programmer with RPi

[seanshpark]

Build a programmer with Raspberry Pi.

• use my old Raspberry Pi 3
• try with I2C + MCP23017 to communicate

why?

• we need 8bit + several control signals
• my RPi3 is doing nothing
• MCP23017 provides 2x8bit GPIO with I2C interface

[seanshpark]

Datasheet: https://ww1.microchip.com/downloads/en/DeviceDoc/doc0368.pdf

Programming algorithm is described in 11. Programming The Flash

[seanshpark]

Programming needs +12v

• we can use +12v power supply + 7805 regulator
• we can use +5v power support + DC-to-DC

Anyway, we need a logic signal controlled 0V-5V-12V circuit.

--> https://www.embedic.com/technology/details/manufacturing-and-debugging-of-microchip-at89c2051-programmer shows a circuit with 2 NPN + 1 PNP TR for this.

--> with some little touch,

• using https://www.circuit-diagram.org

[seanshpark]

MCP23017 control test

• use rpigpio2 repo for testing
• GPB0, GPB1 to control two TRs

GPB1	GPB0	Out
L	L	5V
L	H	0V
H	L	12V
H	H	12V

[seanshpark]

Invert GPB0

GPB1	GPB0	Out	Etc
L	L	12V
L	H	12V	don't use
H	L	5V
H	H	0V

Output of 0V is necessary with H H input as power on reset state of MCP23017 will be H

[seanshpark]

done