Which MCU ?

[bilko]

I have a board with a 40 pin DIP MCU that I am trying to identify, the manufacturer's details have been scrubbed off. Can anybody narrow it down a little. The crystal connects to pins 38 and pin 39. Gnd is pin 20 and Vcc looks to be pin 40.

[cyberfish]

Is there some kind of programming interface?

[hisense999]

Package and VCC, GND suggest some kind of 8051 but clock connection is different - This need more information about device anc connections is this device really need DIP40 or use only few connection from it, communication ports, power design and voltage etc. etc.

This is not a mistake which you wrote this are 38 & 39 pins for oscilator not 18 & 19 - if is 18&19 then this perfectly match AVR.

B.R.

[mikeselectricstuff]

What sort of vintage is the board? What frequency is the xtal? This may help narrow it down.

[bilko]

Board is from a Xantrex charger/Inverter remote control model RC7
Circa 2000
I looked up the AVR but haven't found a match for the pinout.
Please see attached photo, crystal freq is 4Mhz, no external eprom so assume its a flash device else a OTP.

I am trying to document the protocol between the remote control and the inverter.
It uses a Max201 chip for the comms so I am going to try a serial sniffer.

[Rufus]

Some 68HC05 variants like MC68HC705C8A match that pin out.

[bilko]

Some 68HC05 variants like MC68HC705C8A match that pin out.

Brilliant, I can start following the traces and see if they match the functionality. Well done, saved me loads of time on google.
 
Thanks everybody for you help , especially Rufus for finding the chip.