Enabling 57600 baud downloads

I got tired of the default download speeds of 19200 baud for my MRM board, so I decided to create a loader which would enable higher speed downloads.

This work was inspired by a post on the RoboMinds Yahoo group.

CPU32Bug looks in Flash for a program and then looks in RAM. So I decided to put the loader in Flash and have it look for a program in RAM. The flash portion initializes the CPU speed to 25 MHz and the serial port baud rate to 57600. It then waits for a few seconds to allow the user to press a key to get into CPU32Bug. If a keypress occurs, or no program is detected in RAM, then control is returned to CPU32Bug, otherwise control is transferred to the program in RAM.

I found that downloading programs into flash at 57600 doesn't work. I had to back down to 19200. To get into CPU32Bug at 19200, just press and hold the RETURN key and then press the RESET button. of course you need to change the baud rate in your serial program.

Here are the files:

  • Loader.S Assembly language source code NOTE: the filename should have a capital S as the extension.
  • Makefile Used to build Loader.s19
  • Loader.ld Linker script
  • Loader.s19 Image to download into flash

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Copyright 2006 by Dave Hylands