Confirmed that is the setup. I’ve double checked the cabling tx to rx. Even tried swapping.
If I have the screen/minicom active before I power up the R3 I see a blank screen with an unresponsive cursor. Then plug the power in. There is no activity on the screen at all. As if no data turned up at the serial port from the power on.
As I’ve said, it just worked once. I’ve no idea what changed such that it now does not.
Many thanks once again.
Does it matter how the Dupont connectors are inserted onto the pins? I’d have thought not.
Each connector is 4 sided and one side has a metal square (I used this for the various electrical tests with the meter). I have them all oriented the same way with the sides with metal exposed all pointing to the outside of the board. (same direction as the DIP switches point). Surely this doesn’t matter?
Orientation does not matter on the Dupond. But they are very cheap connectors and the metal curved part that keeps the tension between the connector and the pin gets bend sometimes, resulting in a very poor connection. Surely could have happended after trying so many times. Re-bending or replacing the connector can fix this issue, it happened to me more then once… You can feel the connector fit with some tension and is not too easily removed.
If you want to fix by bending, then you need to take the metal part from the housing first…
thanks. I’ve just tried lightly touching them. There is some looseness between the connector and pin while being completely inserted and it can be lifted a couple of millimetres and there is some wriggle room. but after that its quite firm and needs effort to remove. This is the same with all three pins.
So I tried lots of jiggling and moving around of the 3 connectors. I expected to maybe see some random data shown in the terminal session just as the voltages come and go as signals. But nothing at all. As I say, it’s quite unresponsive.
Disconnecting the USB connector causes /dev/ttyUSB0 to be removed and it gets created afresh every time its connected.
Getting very hard to think of options.
You probably checked the wires are 0 Ohm?
Are the settings saved correctly in minicom?
on this latest USB FTDI adapter? no I can’t. It’s hardwired so I can’t get to the other end of the three conductors (connected to the USB enclosure).
In the other two adapters yes I did check. just did again with one of the other adapters. Conductivity is fine for all of them.
yes. the only one that needed to change from your suggestion was Hardware Flow Control set to no. Did that and restarted minicom to inspect the setting and it showed ‘no’. Much as it originally showed yes prior to changing.
Thanks again. As per your note the Dupond connectors are fairly flimsy and that it does not matter which way they are slid onto the pins I re-seated each of them in the orientation that feels the tightest, with the least movement when they are attached. I used the FTDI adapter as its the newest and has been used the least. No change at all.
I suppose I now need to buy a new R3, unless there is some further creative testing anyone can suggest.
Is there maybe a cheap uART based device I could connect to test that connection? Something that just flashes lights for correct operation or some such. That would show the connection is ok and the device functioning. I previously posted what voltages I could see but don’t know how to interpret.
Sure, you already have it, another usb-uart device.
If you just run an image from sd catd, then you don’t really need the uart.
oh. I don’t quite understand.
Do you mean I could connect the Dupond connectors from one adapter to the pins on another adapter? So I have USB to USB each end, talking to screen -L /dev/ttyUSB0 at one end? what would I see?
If boot the R3 from sd-card (all DIP switches up) rather than NAND or eMMC, how does that help me get a console session?
Thanks.
So do screen command on both ends. Preferably use 2 different hosts. If you plug both adapters in the same host, you are not checking the most important gnd.
If you run a functional image (on any medium, but sd is easiest) you can use ssh. Only when things break down you need uart.
