freqmax wrote:
@HenryCase:
Now you got to check:
1) Does using these pins "the wrong way" interfere with anything else?
2) How to handle the MCLR.
I assume the PIC18 is 3.3V or we have another issue aswell.
I suspect with a special HDL-code and the user holding down the PROG button. One can reprogram the PIC18.
Provided power glitches doesn't happen and certain bits aren't set which requires highvoltage reprogramming.
Page 140-141 of this document,
http://www.xilinx.com/support/documentation/data_sheets/ds099.pdf , shows pin capabilities for XC3S400-PQ208 (used in Minimig v1.1). Pins 86, 87 and 92 are described as "Configuration pin, then possible user I/O". Good to know these pins aren't input only.
The PIC used in Minimig v1.1, PIC18LF252, runs at 3.3V. However this may be an issue:
http://web.comhem.se/illuwatarproject_pages/minimig/minimig.htm"I didn't realise that erasing a PIC requires 5 V"
However, as you can see, Illuwatar has already achieved a form of ICSP for the PIC...
"A larger PIC to make the board funnier. This addition was not really needed, but I wanted to have the option to add an LCD. To simplify things, I just changed the PIC18LF252 to a PIC18LF452. By donig this, I could still use the original code by keeping the original pin assigment. I also added ICSP, but that ended up little bit odd in the first version. As an AVR-guy, I didn't realise that erasing a PIC requires 5 V... The solution will be a bootloader that allows programming of the firmware via the serial port."
We might be in luck, it's possible PIC reprogramming can be done with the current Minimig design:
http://home.hetnet.nl/~weeren001/minimig_building.html"Although the PIC can be directly programmed with the necessary firmware, I strongly suggest the use of a bootloader. A bootlader makes it possible to reprogram the PIC through the serial port. To serial select jumper is designed to facilitate this. By setting the jumper to "MCU", a null-modem cable can be used to connect the Minimig to a PC. This way, new firmware can be downloaded without removing the PIC from the Minimig board. I use the Tiny PIC Bootloader by Claudiu Chiculita. This bootloader is easy to use and works reliably. Please follow the link on the links page to download the bootloader. When you use this bootloader (and you should!) program the file called "tinybld_18F252_20MHz.HEX" (inluded in the Tiny PIC Bootloader archive) into the PIC using a programmer. Then use the Tiny PIC Bootloader download tool to download the Minimig firmware into the PIC. This will make future updates much easier."
How can we check that ACube have included the Tiny PIC Bootloader Dennis recommends in their builds? Is there a way of reading PIC contents at runtime?
