Pyboard entering DFU on power on
Posted: Fri Mar 09, 2018 3:21 am
Hi,
I am facing a very strange issue with my pyboard. The board enters into DFU mode whenever I power on/hard reset, and boots normally only after pressing the reset button.
This started a couple of days back, when I accidentally connected a Li-Po in reverse polarity to Vin. This fried the 3.3V LDO on my pyboard, so I had to replace it. I removed the stock 3.3V LDO and installed a new one (specifically LT1085CT-3.3), across the Vin, 3.3V and GND pins near pin X22.
After the rework, quite strangely my pyboard enters DFU mode everytime I power it on. Everything else seems to be working fine, and I can get the pyboard to boot into python by pressing the reset button. However, the board strangely keeps booting to DFU whenever I power it on/hard reset it. Initially I suspected I may have shorted the 3.3V to DFU while reworking the board, however this does not seem to be the case (my multimeter reads ~10megaohm between DFU and 3.3V in power off state).
I am using my pyboard in a box where the reset is not easily accessible, so this behavior is very annoying.
I also tried reflashing the firmware, but the issue persists. The issue also persists if I power Vin or 3.3V externally with a DC supply.
Did I possibly fry something in the ST when I originally connected the Li-Po, causing this behavior ?
I'll possibly wire up a power on reset circuit, if this is a hardware issue, but want to make sure there is no solution in the SW space.
Any pointers debugging this would be greatly appreciated!
I am facing a very strange issue with my pyboard. The board enters into DFU mode whenever I power on/hard reset, and boots normally only after pressing the reset button.
This started a couple of days back, when I accidentally connected a Li-Po in reverse polarity to Vin. This fried the 3.3V LDO on my pyboard, so I had to replace it. I removed the stock 3.3V LDO and installed a new one (specifically LT1085CT-3.3), across the Vin, 3.3V and GND pins near pin X22.
After the rework, quite strangely my pyboard enters DFU mode everytime I power it on. Everything else seems to be working fine, and I can get the pyboard to boot into python by pressing the reset button. However, the board strangely keeps booting to DFU whenever I power it on/hard reset it. Initially I suspected I may have shorted the 3.3V to DFU while reworking the board, however this does not seem to be the case (my multimeter reads ~10megaohm between DFU and 3.3V in power off state).
I am using my pyboard in a box where the reset is not easily accessible, so this behavior is very annoying.
I also tried reflashing the firmware, but the issue persists. The issue also persists if I power Vin or 3.3V externally with a DC supply.
Did I possibly fry something in the ST when I originally connected the Li-Po, causing this behavior ?
I'll possibly wire up a power on reset circuit, if this is a hardware issue, but want to make sure there is no solution in the SW space.
Any pointers debugging this would be greatly appreciated!