Hi Parallax Team,
I have recently migrate my project from a integrated BS2P-24 to a BS2P-40 OEM microprocessor to allow for more pin as i also moved to a parallel LCD display and of course to reduce cost. I have prototype the new display using the 4 bit LCDCMD and LCDOUT commands and got the "Hello World!" test working fine so i'm not too worried about that part, but it seems when i moved the electronics onto a custom PCB - see attached PDF of the CPU schematic which closely mirrors the CPU schematic shared on Parallax webiste, (https://www.dropbox.com/s/b1t6pxbo713dkfw/BS2P-40 CPU Schematic.pdf?dl=0
), the processor seems to be dead. When i upload the code onto the board into the SEEPROM from the laptop it detects that a BS2P-40 is present and all of the files (multi-program) load successfully so i have to think that the code is present and loaded correctly.
There is +5V flowing onto the board and other parts of the board work properly.
As a simple test i defined Pins 0-6 as =1 (+5V) and used a multi meter to test the values and all of them seemed to be floating around 0.5 V. I am going to see if my reset logic (using a MAXIM 706 IC - (https://www.digikey.ca/product-detail/en/maxim-integrated/MAX706SESA/MAX706SESA-ND/1513257
) connected to pin 7 is working, but after that, I'm not sure how else to tell if the CPU is working properly?
Any advice would be appreciated.