Homebrew PCBs

"awakephd" <a_wake@...> writes:
> I'd like to hear more about this one -- are you saying that you
> don't need anything other than a serial output -- no JDM-type board
> or anything? I assume there is a pin that must be signalled to put
> it in programming mode? Does it use a fixed baud rate, or ??
> 
> This part sure does sound interesting!!

Go to http://people.redhat.com/~dj/m32c/

Click on "Easy R8C/M16C/M32C Flash Programming" and read :-)

The link under it is a sample flash downloader program.

Basically, you need three things to program:

1. To be able to reset the chip (duh)

2. To be able to assert the MODE or CnVss pin (a two-pin jumper is
   fine) during reset.

3. An asynchronous logic-level serial Tx/Rx pair (i.e. serial port)

On most of my boards, I include an FTDI232R chip which lets me control
all those signals (and more) over USB, plus serve as a serial console
when it's running.  However, the standard E8a connector brings all
those signals out anyway, so you could have one usb-based programmer
for all your boards.

I've also done live updates, using one MCU to update another, in my
furnace controller - the gumstix board can reprogram any of the five
R8C chips while the system is running.  (most of the R8Cs have I2C,
they make great "smart peripherals")