tagged how easily can I get back into an old project? (CO2 monitoring) # prev single next top
About 10 months ago I acquired a CO2 sensor (Sensirion SCD40), I attached it to a D1 Mini ESP8266 microcontroller, and for a week I looked into CO2 monitoring. At the end, I set up an InfluxDB database, and flashed the microcontroller to get and upload the CO2 data every 30 seconds. Eventually, I set Influx to delete data over 7 days old (as I didn't want to make a weird historical "is anyone in the room" sensor), and from then I could visit my Influx to see how much CO2 was in the room the sensor was in.
Since then, I have:
- forgotten a lot of how I did it
- stopped using VSCode (started using VSCodium), which I used to flash the microcontroller using the PlatformIO extension, which doesn't work in VSCodium
- stopped using Windows (started using Linux)
I wanted to re-use the sensor at an environmental talk today, so I grabbed it and started a small task. But, I didn't know whether it would be easy to reprogram the device, or to get data from it, or how possible it would be, as I no longer use either the OS (Windows) or the tool (VSCode) I used. I knew that PlatformIO had a CLI (Command Line Interface), so I didn't need the VSCode plugin to use it, and I knew programming/serial communication was probably easy enough on Linux. To be honest, I would rather know how to use the CLI than the plugin, as I prefer this most of the time. Then, when I write instructions, I can write commands instead of writing "press this button in the GUI".
I'd written a lot in the documentation on the project, so hopefully I didn't have to remember much. This is what I had to remember...
- I had to install platformio (PIO). I did this using their installer script and then I linked the CLI executables with
lnfollowing PIO's instructions - I ran
pio runand it built the binaries fine - when I plugged in the microcontroller, it was not showing when I ran
pio device list- it was showing under
lsusb - I ran
dmesgand it showed that the USB device connected tottyUSB0and then immediately disconnected. I googled the error, which it turns out was about something calledbrltty, which is a braille program of some kind. I uninstalled it, as I don't use braille devices, and all was now good.
- it was showing under
- I was able to use
pio device monitorto see the messages being sent via Serial. When I most recently programmed the microcontroller, I accidentally left the Serial communication on (I'd made an option to disable it), which in the end was helpful - I realised you need
pio run -t uploadto upload the firmware to the microcontroller, but it failed. I needed to update someudevrules. There was a link in the error output to a page which had some commands to do this
After all this figuring, I was able to reflash the microcontroller to just send environment information over Serial (i.e., not push to InfluxDB), so then I could use some commands to display a big "604 ppm" on my terminal screen.
# log from monitor
pio device monitor --quiet | awk '{printf "%s\t%s\n", strftime("%H:%M:%S", systime()), $0}' | tee env.log
# display nicely
tail -n1 env.log | awk -F'\t' '{printf "%s ppm.", $2}' | figlet -t -c
# plot
# install eplot and chmox +x
cat env.log | awk -F'\t' '{print $2}' | eplot -d -t CO2