I bought an arduino compatible board here: http://unsigned.io/projects/micromodem/ and am trying to flash new supported firmware onto it. The only instructions given to flash the board is to use the command avrdude -p m328p -c arduino -P /dev/ttyUSB0 -b 115200 -F -U flash:w:YourFirmwareFile.hex .

I'm trying to follow the tutorial here using an Uno as a programmer: https://learn.sparkfun.com/tutorials/installing-an-arduino-bootloader#uploading-code---hard-way but I don't know what to use for the fuse settings. I've tried a few different fuse settings such as the one for the Uno, and default 328p ones using a fuse calculator but it seems like they all have unpredictable results. Some fuse settings make it so that I can't connect to the COM port at all to monitor the traffic, and others let me connect, but send a message of . I'm expecting an introduction message from the firmware that is supposed to be built in.

Thanks for the help.

  • Hi, I like to use a gui front for avrdude called avrdudess it might help you read the fuse settings from your modem board. Also remember that fuses are inverted, meaning a 0 means activated.
    – Hans Neve
    Mar 26 '16 at 12:42
  • Hey, thanks for the response. I'll definitely check this out as it seems easier, but I'm trying to figure out what settings to use that would work my with the new firmware. I don't think reading the current fuse settings off of the board would help very much unless I had a working one already. Unless I'm understanding what you're saying incorrectly.
    – ipwnatlyfe
    Mar 27 '16 at 2:59
  • Ok, what do you want your fuse settings to do? Are you using a crystal? Do you need power brownout? Do you want to lock your chip from ever being programmed again. There is many settings in the fuses that can mess things up so please tell us what you want and why, and we'll try to help.
    – Hans Neve
    Mar 27 '16 at 11:45
  • I don't really have any information other than the board and the specs of the board. I would like to load a different MicroAPRS firmware than the current one that is on the board and listed on the same project link above. To load that firmware I was trying to find the appropriate fuse settings so that I could get information from the serial port, as well as load my own programs on the board.
    – ipwnatlyfe
    Mar 27 '16 at 20:42

Normally you don't need to change the fuse settings, this configuration should be fine with the default arduino setting of




Serial should work fine.

  • I tried using those fuses. Here is a link to the pictures of what I am trying and the result is the serial port is always busy. imgur.com/a/dU71h I changed the baud rate that was given for flashing the modem (115200) to (19200) because every time I used 115200 I would get an Out of Sync() error and it wouldn't do anything.
    – ipwnatlyfe
    Mar 28 '16 at 9:52
  • Not sure if you can change fuse settings by serial programming...
    – Hans Neve
    Mar 28 '16 at 12:32

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