IOT Temperature Alarm System using hologram.io cellular service.
- Sends TCP messages to Hologram. Which then sends out SMS alerts to the cellphones that want them.
- Now monitors and messages about Power Loss, in addition to Temperature Switch Alarm.
- You can power on with dip switch #4 set to on to skip SARA modem init.
- You can hold down button C on the OLED to power down the SARA modem.
- Green LED flashes when a message send is pending, otherwise it breathes lighter and dimmer.
- Subtle pixel shifting of text to try to head off OLED burn-in.
- Passes Arduino USB terminal text over to SARA when the state machines are not busy with their command.
- Echoes text back to terminal if it originated from terminal.
- If you press Reset button on the OLED, the display will blank. It does not reset the RP2040. This is an Adafruit choice.
- Reset for the RP2040 is unlabeled, but it is the button nearest the USB connector on the side.
- The Adafruit battery is protected from over discharge, but the RP2040 could go haywire at low voltage (untested).
- LOL no message rate limiting if sensor would continuously be toggling. YOLO. (Hologram would ban after a while anyway).
- Serial Debug text stuff not quite removed yet. Nor am I comfortable removing it yet.
Adafruit SH110X, Adafruit GFX Library
Edit Arduino_secrets.h with your device specific Hologram key. Key needs to be unique from hologram.io dashboard.
| Command | Description |
|---|---|
| AT | OK is what it should respond with after typing A T and then pressing enter. Both Linux or Windows style Carriage Returns / Line Feeds are acceptable from a serial terminal. |
| AT+UPSV=0 | There is a default power saving setting which disables the UART after 6 seconds of inactivity. Leaving that on will drive you insane. Also good luck typing this within the first 6 seconds, buddy. Better keep spamming AT. |
| AT+CPSMS=0 | Disable PSM (Power saving mode OFF, if only it would wake up properly this would be useful). |
| AT+UMNOPROF=100 | The Challenger startup aggressively sets Standard Europe automatically so just go with this profile. |
| AT+CFUN=15 | Soft reset. |
| AT+UBANDMASK=0,2074 | Bands available in the US are 2,4,5,12,13. That would be 6170. |
| AT+UBANDMASK=1,2074 | However band 13 is causing issues at install site, so using 2074. |
| AT+CFUN=15 | Soft reset. |
| AT+CGDCONT=1,"IP","hologram" | Set the APN. |
| AT+COPS=0 | Automatic Operator Selection (this is causing me problems, only US Cellular or AT&T wants to talk but it hops over and gets denied anyway.) |
| AT+CFUN=15 | Reset modem. Parameters get saved only during soft reset command or soft shutdown. |
| AT+URAT=7 | Might help to set LTE Cat M1 technology only. |
| AT+CFUN=15 | Requires a soft reset as usual. |
| AT+CPWROFF | When you want to remove power you should tell modem to shut off first. Wait a few seconds after OK. Hard reset when downloading to the RP2040 will cause issues unless you issue AT+CPWROFF first! |