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Slow clock mode for AVR doesn't work #103
Oops - meant to look into this more....
"slow clock mode" only works once the AVR programmer is open. Is that still erroring out? Slow clock is a big hack that slows down the SAM3U core clock speed, as you can't divide the SPI clock to be low enough when running from the 96 MHz clock.
Everything else goes out the window when this happens - the FPGA communication etc won't work reliably once it's enabled.
Those are the steps I was following:
And the following steps always resulted in an error and I ended up using an external programmer to set the fuses and be able to use the CW-lite to push firmware.
Should be fixed by 073aba8. Basically, the delays on the Sam3u became too long when in slow clock mode, causing USB to time out. ChipWhisperer now tells the Sam3u to use smaller delay values when in slow clock mode.
Let me know if the issue is fixed and I'll close it.