UART on IO0/IO1 not working since V3.5.x using an Arduino Nano

[jay_s_uk]

@mule we're on 3.5RC3 so just jump straight to that to test it

[dc42]

@mule also please confirm what M575 command you are using to enable the UART.

[mule]

@dc42 @jay_s_uk I tested it with 3.5Beta1, 3.5RC1, 3.5RC2 and 3.5RC3. None of these versions did work.
On the Arduino Serial.available() always returns 0 with these firmware versions.

I now did another test with IO0 and it has the same issue (although a panel due connected to IO0 is working fine). I therefore edited the topic. With 3.4.6 IO0 works flawlessly too with the Arduino Nano.

What I do not know yet is, if it is only an issue receiving anything from the duet board or if there is also an issue sending anything to the duet board from the Arduino Nano. Is there any way to see what the duet receives via the UART ports?

Regarding config via M575 I am using:
M575 P1 B57600 S1
M575 P2 B57600 S1

I did also try M575 P2 B57600 S2 but it did not change the behaviour.

[dc42]

@mule bear in mind that when you use S1 in the M575 command, a checksum or CRC must be received for input to be considered valid, and the output will be JSON-formatted for PanelDue. If you want to send/receive raw data without needing a CRC or checksum then use S2 instead of S1 in the M575 command. But I see that you tried that already.

[mule]

@dc42 I am using the Arduino Nano in order to get the printer status, print progess, heater status and temperature in order to display it including animations via Neopixels. Therefore I send different M409 (.e.g. M409 K"state.status) to the duet3.
The issue with V3.5.x is that the Arduino Nano not even get a single byte of response via UART after sending the M409.
Is there a way to see if the duet3 receives the M409 at all? Or do you already have an idea which change between V3.4.x and V3.5.x could cause this different behaviour?

[dc42]

@mule you can use M111 P3 S1 to enable GCode debugging. That will echo to USB all GCode commands received from any input.

I have done some tests and established that with the latest firmware build, GCode commands are received from io1 and M118 messages are sent to it, but a PanelDue connected to it does not get any responses sent to it.

[mule]

@dc42 I can confirm that with V3.5RC3 PanelDue stopped working on IO1. Very weird.

[mule]

I just activated debugging via M111 P3 S1 and it showed the M409 gcodes being sent from the Arduino. But the Arduino gets no response from the duet.

[dc42]

@mule please try the new firmware at https://www.dropbox.com/scl/fo/p0136wx04h8xf6ejwdnn9/h?rlkey=efrfwyb6o5tqid11gustz3uvy&dl=0 and let me know whether this fixes the problem.

[mule]

@dc42 I can confirm that the new firmware fixes the issues. Many thanks for the quick fix!

[dc42]

@mule glad to help. Thanks for reporting this.