Wireless UART for debug purposes

There are plenty of Bluetooth modules with UART connections, but of course you need something at the other end. A couple of Silicon Labs evaluation boards can be configured as linked to each other - then they can act mostly like a UART cable with a wireless cable, with very little effort.

If you need to have the Bluetooth module inside the device, and have one master PC talking to lots of devices, then you'll need to do a bit more work. And if it is always installed, then suddenly your device is classified as a radio communications device, with all the standards, certifications, EMC rules, and testing that goes along with that.

If it is okay to plug something temporarily into the board that needs debugged, you could set up a Rasberry Pi with a USB battery pack, and plug that into your TTL-level UART debug signals on the board. Then you can have Wifi configured in any way you like. A tty to tcp/ip port converter for remote access should not be difficult to make - with Python Twisted, it's probably no more than a couple of dozen lines.

I know I can design my own solution, maybe using some evaluation boards.

However I was asking about something ready to use. Plug the wireless adapter on the debug UART of the device and open putty on the remote PC (here remote means reachable by the RF signal, whatever it is).

As I say, look at Silicon Labs Bluetooth modules. There's no point in me trying to give the details of the devices I used, since that was three or four years ago, but those were close to out-of-the-box - just configuration and setup, using the Silicon Labs mobile app. (I was communicating between two other cards, rather than a PC, but that should make little difference.) There are no doubt a dozen different vendors with similar solutions.

You haven't said if you need this for two systems or two thousand systems, so that's the best answer you can get so far.

I will check.

In the meantime, I found many UART/WiFi adapter based on ESP-01 module. I think it should be ok.

Less than 10 pieces should be ok :-D

Yes, I would expect it to be easy to get hold of such modules and ready-made software for the ESP-32 if you prefer Wifi.

Just make sure that they are not considered part of the main system that you make, so that you don't have to test and certify them.

Was it this kind of thing:

Do you just hook up TX and RX and the default firmware does the rest, or do you need to program it first?

Seems like it's a common thing:

and I see there are some Chinese versions for about $2 + shipping: for wifi: It's the kind of thing that's potentially useful to install just in case you need a recovery console on something like a router, which you can set up ahead of time so you have access without taking the thing apart when you're in a jam. Although not entirely happy with the security model of something broadcasting its pairing ability all the time when not in use.

Theo

Am 13.11.2023 um 09:10 schrieb pozz:

Define "far", and "UART"

If the interface is actual RS232 of modest baudrate, it could be as simple as: make the RS232 cable long, so the USB doesn't have to be.

Or remote control a notebook connected to the devices UART via ssh or RDP (if you are using Windows).

Il 14/11/2023 19:47, Hans-Bernhard Bröker ha scritto:

10-15 meters should be ok

Standard TX and RX asynchronous signals as in RS232 standard, but at UART low level voltages (3.3V or 5V). Baudrates that I often use are the standard from 9600bps up to 115.2kbps.

The problem with a long cable is often the position of the device that is uncomfortable to reach. Moreover, if I want to record a long session log (for one or more days), the long cable isn't an option.

As I said, the device is difficult to physically reach and it is often impossible to install a notebook near it.

Am 20.11.2023 um 08:29 schrieb pozz:

Then you need an active device that shifts and boosts signal levels, a good deal closer to the machine in question. A MAX232 equivalent in a box small enough to count as a plug casing would probably do it.

"Uncomfortable" should only rule out doing that for use cases at or below the urgency of "nice-to-have."

Or, to put it differently: if you can't even get there with a suitable plug attached to some thin-ish cable, that puts the situation beyond "uncomfortable," into the realm of "practically impossible to use."