Panel Due Bad Command Error From CNC Pendant

[dhusolo]

I have:
Duet 3 with RRF 3.3 ran off a RPI 4 as SBC
FYSETC PanelDue 7i clone with
Arduino Nano CNC Pendant from here

To be clear the pendant works if It's connected to a Duet 2 WiFi or Duet 3+ Mini

When I connect the pendant to use the PanelDue pass through I receive numerous "Bad command" errors. I have it wired as the webpage says.

Arduino TX w/ 6k8 resistor > Duet Io0.in
Arduino RX > PanelDue DOut
PanelDue DIn > Duet Io0.out
1k resistor on the back replaced with 10k

[dc42]

@dhusolo I can see a few possibilities:

1. Do you definitely have the PanelDue set to the same baud fate as the pendant, normally 57600 baud?
2. The Arduino Nano really needs a 5V signal level from the PanelDue, however PanelDue outputs a 3.3V signal level (that is why I reworked the pendant to use a Arduino Pro Micro or Leonardo, because those Arduinos are happy with 3.3V signal levels even when run from 5V). So perhaps the signal level is the problem. What did you mean by "1k resistor on the back replaced with 10k" ?

[dhusolo]

@dc42 Yes the Pendant is 57600 as well as the PanelDue.

In one of the original posts I saw that with a CH340 on the Nano clones you might need to replace the 1k resistor so the PanelDue can override the RX signal from the USB.

Sounds like I might need to incorporate a logic level shifter

[dc42]

@dhusolo thanks, I remember now about changing the 1K resistor t 10K, in order to improve the signal level from the PanelDue data out pin into the Arduino.

[dhusolo]

@dc42 To confirm the logic level shifter is wired Paneldue side is 5v and Arduino side is 3v? or do I have that backwards.

Also is the 1k resistor swap on a nano really needed?

[dc42]

@dhusolo PanelDue uses 3.3V signal levels, Arduino Nano uses 5V. If you use a level shifter then you probably don't need to change the resistor.