Duet 2 Ethernet and SBC

wilriker

@smoki3 Please try lowering it incrementally by dividing by two, i.e. try 4MHz, then 2MHz and so on until you either get to somewhere around 100kHz or find a working speed

I will try to reproduce your setup next week. Just to be sure: did you power the RPi from a buck-converter off of the Duet or did you power it separately?
Also if you only tried one of these options so far please try the other.

I also use loose wires of around 150mm length with Dupont crimps on the ends and several JST connector pairs in between to insert/remove resistors.

smoki3

@wilriker I tried a buck converter and a USB power supply - results in the same behavior.
As soon I disconnect the power from the duet and just plug in a USB cable it works with out any issues.

Lowering the speed doesn't help. Tried it down to 1MHz.

Actually I also use Dupont connectors with a cable length about 8cm.

smoki3

I now tried to lower the speed down toi 100kHz. But this also doesn't help.

Its really as I said, as soon I plug in VIN to the Duet the SPI Bus is broken

smoki3

Is there a reason why on my duet2 ethernet capacity C99 is not equipped? Is a capacity in the 5V buck converter.

I looked at the schematic normally there should be a 250uF capacity. Could this be a reason?

A Former User

which revision is the board?

wilriker

@smoki3 On my 1.03 board C99 is populated. My meter refused to measure the capacitance but it's certainly higher than "none".

@T3P3Tony might answer this question better if that would pose a problem (I'm primarily a software guy ).

smoki3

@bearer Its a 1.04c

A Former User

@smoki3 said in Duet 2 Ethernet and SBC:

1.04c

iirc its normal then, it was fitted to 1.04, 1.04a and 1.04b but not 1.04c.

also given the cpu and wifi runs off 3.3v with its own smoothing cap i'm not sure it matters, but I can try it next week if I manage to throw together a printed part with pogo pins for the wifi (edit: printed part is modelled for P50 + R50 pins, may need to drill out holes)

A Former User

@smoki3 seems I've missplaced or run out of pogo pins, and with logistis being what it is I doubt I'll test it any time soon.

maybe you could try soldering a regular radial through hole capacitor to the pads and see if it helps? (or see if Tony has anything to add)

smoki3

@bearer I don't have capacitor by hand

wilriker

@smoki3 First of all I can confirm that with external PSU I see the same behavior. I need to check the cause of that next.

A Former User

@wilriker said in Duet 2 Ethernet and SBC:

with external PSU

as in external 5v?

wilriker

@bearer As in external 24V going to VIN of the board.

wilriker

So what I can see is that it does not have anything to do with the internal 5V regulator. If I connect the Duet via USB to the RPi and remove the jumper for internal 5V, i.e. I_5V_EN (completely or put it on E_5V_EN - does not matter) the same problem occurs. So VIN is somehow messing with SPI as soon as it get's to fast transfers as it seems. Still checking.

A Former User

Hm, will try to repeat test with 24v and get the scope out, was under the impression I had used Vin but could be organic bitrot..

smoki3

@wilriker I also tried to disable the internal 5V converter by removing the the jumper. But I also does not help

smoki3

Is the ethernet module also working over SPI?

wilriker

@smoki3 said in Duet 2 Ethernet and SBC:

Is the ethernet module also working over SPI?

Yes, it does.

smoki3

@wilriker Then its even more wired that it is working with the ethernet module and not with a raspberry

A Former User

@smoki3 said in Duet 2 Ethernet and SBC:

Then its even more wired that it is working with the ethernet module and not with a raspberry

Maybe try if the wireless wifi is better? Jokes asides, I find not all boards are the same; will try to log some data and take a look at the signals.

edit: maybe one of the regulators need a minimum load that you loose when removing the ethernet - just something that hit me on the way out