Thanks for your support.
Got my new Wiznet 5500 function boards in early this week, and today went to see if I could get Micropython ethernet working on a STM32 with a mainboard double and a STM32 MCU board.
Here's what I observed initially.
1. Plugged Ethernet function board in slot 0.
2. STM32 MCU already installed.
3. Plugged in USB connection in PC using mainboard connector.
4. Used reset/boot pattern to enter boot loader, no USB device enumeration observed.
Next, decided to remove ethernet function board and retest. Still unable to enter STM32 boot loader from USB.
Following that, wanted to determine if MCU may have been faulty.
1. Removed MCU from mainboard and installed in a different carrier board (SparkX featherboard).
2. MCU cannot enter bootloader / no USB enumeration observed.
3. Thinking I have a bad/zapped MCU, in this case.
Next, still want to get Micropython working. I have spare STM32 MCUs installed in other carrier boards, so I:
1. Tested to ensure that STM32 boot loader would enumerate USB on an extra mainboard single. Tested OK - saw boot loader connection
2. Removed STM32 from mainboard single, and installed in mainboard double used previously above. (no function boards installed at this time).
3. USB boot loader NOT enumerating.
Lastly, since I just removed the STM32 MCU board from a just confirmed, working mainboard single, I wanted to see if the MCU was damaged, or if it was jus something amiss with the main board double. So I:
1. Removed newly installed STM32 MCU from suspect main board double, and placed in back into original main board single.
2. Observed NO USB enumeration. Also, noticed that while PWR LED is ON, did NOT see 3v3 LED turn ON.
3. After a few minutes, went to unplug the board and noticed that the bottom of the board near the USB connector was warm.
4. It appears to me that main board double is damaging the STM32 MCUs.
Next, reviewed function board hookup guide and read up on two jumpers settings to re-map power to MCU pins, depending on board. Jumpers for function 0 and 1 are in default position - slide to the 'right' of the battery JST connector. From my reading those two jumper positions should supply power to function cards properly.
However, since we're dealing with a brand new function card, of which has the capability of a POE power supply to the main board, I wonder if there is some influence from this part. Note, the Ethernet function board was NOT plugged into any POE switch during any of this testing.
1. While I cannot say for sure the mainboard double was working properly *prior* to plugging in the POE function board, it is clear now that the mainboard double is now damaging STM32 MCU cards. I appeared to have lost two MCU so far, and am loathe to test any additional ones.
2. In the POE function board hookup guide is mention of several configuration options. Did not alter any jumpers, and installed as was shipped by SFE. I'm not skilled enough, nor willing to risk additional products, to further diagnose whether the POE function board created this situation, or to determine how the mainboard double is damaged.
3. Inspected M.2 pins for any contamination or bridging - all clean. Reseated boards during the work above.
1. I'm welcome to any suggestions on how I can isolate the problem. I've got a scope and a multimeter.
2. Is it possible for SFE attempt to reproduce this issue, by:
A. Placing a STM32 MCU card in a Micromod main board double - using boot/reset button pattern confirm that boot loader enumerates USB connection to PC.
B. Next, place new Ethernet Wiz5500 function board in slot 0, and determine if the boot loader will continue to enumerate?