32u4 runs at 1/8th speed on restart

Development Boards Arduino
1

I’m running a Pro Micro clone with an atmega32u4. Here’s what happens.

I upload the pro micro bootloader using AVRdude using the SF avr pocket programmer. No problem.

I upload the Blink example sketch via usb to prove I am pushing code correctly. No problem, the LED starts blinking.

Then, the board, which had been on COM8, disappears and a new COM7 shows up in the IDE.

The weirdness occurs if I unplug the board. As soon as I do plug it back in (either to USB or external power) the blink sketch starts - at a fraction of the normal speed! My 1 Hz blinking is now about 1/8th Hz. Also, the COM7 port continues to show up, not the original COM8 that allowed successful sketches to upload. I cannot upload a second sketch to the board via the new COM7.

In order to upload new sketches, I have to burn the bootloader back to the board and upload the sketch again…and repeat. Has anyone ever had a board spontaneously change speeds after cycling the power?

2

I solved this by adding setting my fuses during bootload:-U efuse:w:0xcb:m -U hfuse:w:0xd8:m -U lfuse:w:0xff:m

Turns out the 32u4 likes to go into sleep mode unless you set the fuses to keep it awake.