I want to build a lora node to transmit 3 temperature readings from DS18B20’s and one 0-5V analogue pressure sensor to TTN. I have not been able to find an off-the-shelf solution, hence the need to make my own. It needs to be battery operated and will transmit every 5 minutes. I have some experience with RPi and Thonny IDE so would like to stick to that environment.
I’ve looked over resources on Core webpages and I think the following will do the job:
RPi Pico or Pico 2
Makerverse LoRa-E5 Breakout or SX1262 LoRa Node Module for Raspberry Pi Pico, LoRaWAN
PiicoDev LiPo Expansion Board for Raspberry Pi Pico
Makerverse™ Nano Power Timer HAT for Raspberry Pi Pico
rechargeable or non-rechargeable battery
What are the pro’s and con’s of above? Are any of the components incompatible? Are there better alternatives?
The SX1262 comes with a more robust external antenna so I prefer that.
The pressure sensor will probably need to be powered off between readings to save power. The timer hat will do that, but what does that mean for joining the lora network? - does the node have to join each time or can it just wake up and transmit that data without going through the join process?
Many commercial Lora nodes use non-rechargeable batteries - is that a better/safer choice than rechargeable?
Hi Steven
Just butting in with my 20 cents worth here.
If you are transmitting data every 5 mins is there any power saving worth shutting down to “save power”. I would think any power saved would be negated by that used in the start up phase. This would save some complexity and could be worth thinking about with the idea of keeping everything as simple as possible.
Cheers Bob
From memory at a high level, TTN users loraWAN. As such you will need a loraWAN Gateway, that users loraWAN Radio to talk to the end devices, and IP to send the data to the TTN Network servers.
Each node, then needs to support loraWAN (as per how your gateway is setup).
For the gateway, there will be a few options. A common one here was the one on a Raspberry Pi with the loraWAN Hat.
I have a Dragino gateway, receiving data from a few Dragino nodes already, but these are all off-the-shelf plug and play devices. I’ve not attempted my own diy nodwe yet.
For staying with Thonny/MicroPython, I’d lean towards the Makerverse LoRa-E5. It handles LoRaWAN through UART AT commands. The Waveshare SX1262 needs more software work, its supplied LoRaWAN example is C/C++. The E5 supports an external antenna too.
As for the battery, that’s really going to depend on how everything runs under real-world conditions. Measuring power consumption is worthwhile before investing in any specific battery, especially since five minutes of idle current can add up. Cutting power means the firmware needs to save and restore the LoRaWAN session, including frame counters, or join again. I wouldn’t assume either setup handles that automatically.
