SPI 3.3V rail not working Duet 3 6HC+EXP3HC

Alex.cr

Does anyone know how or why the 3.3V rail on the daughterboard connector might not be working for a 6HC or 3HC?

I have an RTD daughterboard that I want to use on my 3HC. I set everything up and briefly got a response using the 100OHM resistor. When I moved over to the PT100 I couldn't get anything. I then swapped it over to the 6HC which had a DHT22 hooked up working and could not get a response out of the PT100 either. I double checked the PT100 and it is not grounded out anywhere and am getting a resistance that makes sense out of it at room temp using a multimeter.

I then started looking around and noticed the 3.3V pin at the daughterboard on the 3EXP was not giving any voltage but the 3.3V pins on the IO are putting out appropriate voltage without issue. The 3.3V LED is on as well.

I hooked the DHT22 back into the 6HC and was unable to get a response out of it now using the standard daughterboard pins. If I plug the + wire from the DHT22 into a 3.3V IO pin it starts working again.

Did I somehow fry the 3.3 supply pin to the daughterboard connector on both of my boards? Is that possible without pulling down the rest of the 3.3V rail? Anyone seen this before?

I am tempted to plug the RTD board into a duet2 wifi that I have but really don't want to fry anything else if that board is the problem.

My SBC communications to a RPI4 seem to be working fine still.

dc42

@alex-cr said in SPI 3.3V rail not working Duet 3 6HC+EXP3HC:

I then started looking around and noticed the 3.3V pin at the daughterboard on the 3EXP was not giving any voltage but the 3.3V pins on the IO are putting out appropriate voltage without issue. The 3.3V LED is on as well.

There are two 3.3V rails on the 3HC (and on the 6HC): an "internal" one for the processor, other on-board electronics and the daughterboard connector, and another for the +3.3v power on the IO connectors. The green LED indicates whether the internal 3.3v supply is present.

Did you measure the 3.3v pin on the 3HC daughterboard connector with the daughterboard removed? If so, then the most likely reason for not getting +3.3V on pin 8 of the daughterboard connector is a bad solder joint on the connector itself. Does that joint look OK?

Or did you have the daughterboard connected, and you were measuring the 3.3V pin on the daughterboard itself? If so then check for an unsoldered pin on the connector on the daughterboard. That connector has to be hand-soldered, so it's not impossible that a pin has been missed.

Alex.cr

@dc42

I screwed up while measuring voltage the first time and was connected to the NC terminal at the daughterboard. Idiotic move on my part. I can now measure 3.3V if i hook up to the bare connector and through the daughterboard.

The daughterboard appears to be not responding. I ordered another to test to see if maybe something is just wrong with this one.

Alex.cr

@alex-cr

If anyone is reading this. My future advice is to make sure you include all sets of quotation marks as required when defining anything especially heaters... It will save you a lot of time and cash in thinking you fried daughterboards.

dc42

@alex-cr said in SPI 3.3V rail not working Duet 3 6HC+EXP3HC:

@alex-cr

If anyone is reading this. My future advice is to make sure you include all sets of quotation marks as required when defining anything especially heaters... It will save you a lot of time and cash in thinking you fried daughterboards.

Does this mean that you have it working now?

Alex.cr

@dc42 said in SPI 3.3V rail not working Duet 3 6HC+EXP3HC:

Does this mean that you have it working now?

Yes it is resolved. Turns out it was a combination of me mistaking where the 3.3v actually was and missing a set of quotation marks for the SPI channel during the M308 command.
Sorry for wasting your time!

Side note, you guys do a great job, thank you!

dc42

Thanks, I'll mark this as solved then.