Anyone familiar with Rasp Pi 400, and USB serial connection?

Hardware
1

Perhaps those more familiar can give me a couple hints to try.
I have a Rasp Pi 400 and have installed WeeWx on which runs the simulator fine (I have another Rasp 4 running Weewx and and IP100 Rainwise driver for a year or more, so I have a smidge of experience, but am in no way a Raspian expert).

Here’s the thing. I have a couple stations that have (supposedly) drivers for WeeWx and are close enough to my computer to fiddle with and learn something and maybe even get another station on line.

I have used the USB to serial converter cable with two other Windows based computers, and when plugged into either the Tex. Wx. Instruments 8000 or the Vaisala WXT520 and attach it to the Weather Display software, they both work just fine, ingesting and displaying the readings. I also have fired up a copy of TerraTerm and looked at the serial stream and it displaying readings each second. So I am pretty confident that the stations work, the USB/serial converter and software work, and they can be configured to work at least with Windows.

I know drivers can be tricky, so even with some degree of concern, I did start WeeWx and configure it to use the TWI driver, the lastest one I could find on GitHub for both Python 3 and updated for the next to the last version of WeeWx. Nothing. I tried the 0 and 1 ports both in software and by switching the two around with the USB plug on the 400.

I got a terminal program and started it. Nothing coming in to display. I looked at the log and it says that the USB/Serial driver was successfully installed. I changed through each of the serial speeds, from 1200 up through 19200 for each of the stations. Nothing.

I would think I need to walk before running, or even crawl, so my main focus now is to try to get to see the input stream on the terminal emulator. Some stations are set up to send a data stream constantly, others only when polled, so for the TWI I looked up the commands that need to be sent to get a current data stream, a hi/lo dump and so on and tried sending them from the keyboard to the station. I don’t even see any send/receive lights on the little USB/serial monitor dongle.

That leads me to believe I’m missing something in the configuration of the Rasp 400.

Can anyone give me a hint as to what to possibly try next? I know there have been reports of the Rasp 400 running WeeWx OK, but a couple I’ve found use stations that I don’t have and drivers which obviously won’t be of any value.

Thx. Dale

2

The latest released TWI driver for WeeWX doesn’t work, at least it didn’t for me. I’ve attached my corrected version that works with WeeWX 4.10.2. The USB<->Serial device usually appears on /dev/ttyUSB0. I created a pull request to integrate my changes into the released WeeWX version but the interest in TWI weather stations is practically nil. Copy my version where your current version of twi.py resides, typically /usr/share/weewx/user. Hope this helps!
twi.py.zip (4.1 KB)

1 Like
3

I can attest to this twi.py code working.

I did modify it slightly, making my WLS station the default, and mapping the outside temperature as it was pulled from my station into the solar radiation number, since that is what it is.

I’m no programmer so I was able to do this relatively easily but don’t understand some of the complexities of this code. It just worked!

Thanks for those who have the knowledge and experience to share there work. I absolutely would not have been able to do it without this code.

When there are popular stations, those of us with older stuff or fewer users might seem left in the dark, but the WeeWx team and Russ have helped me tremendously.
Dale