HP67 running

[teenix]

Hi Bernhard,

I looked at your HP-01 pics (excuse the pun) posted the other day and the PIC there is the same model as I chose to upgrade the calculator to host the 67 emulation - (16F1519).

I rewrote my PIC programmer code the other day code and it now handles this chip. I also rewrote the emulator code for it and it seems to simulate ok but haven't tested in the actual chip yet.

My setup has a bit banged I2C link to the memory card. When instructed, the code read/writes the chosen memory block in less time than the finger comes off the button but I purposely delayed it to blank the display briefly for user feedback.

This is a fairly easy approach and works for the 65 reader. I will incorporate the 67 CRC code once I know I have the new chip under control, but it still won't have to scan a real card.

I wouldn't expect a PIC to have much trouble bit banging the serial data in on any input pin unless logic level conversion is required which would require an external buffer. I've written a few duplex RS-232 applications at 19200 baud using this approach. An edge detect interrupt could be used to frame incoming data bits and shift them into a buffer easily enough.


cheers

Tony