Jeenode micro as weather monitor

Added by tonym about 2 months ago


I was planning to set up Jeenode Micros to monitor temp and humidity using I2C sensors, my current favourite being the BME280.
I have the sensors already running on a couple Jeenode USBs, sending data every minute to a JeeLink connected to a Linux server running cacti/rrdtool.

I would prefer to use the Jeenode Micro mainly due to size and power consumption, but I'm not sure if this is feasible or advisable.
Does anybody have the BME280 or other digital temp & humidity sensor running on the Micro?
All references I have found online for the Micro are using analog sensors, and I was also concerned that the code might be too large...

Is power consumption on the Micro significantly lower than the Jeenode to justify the extra hassle involved?

I am planning to run the nodes with LiPo batteries and have them out of the way, so the size of the Jeenode SMD/USB is also acceptable, assuming any extra consumption does not increase battery size too much (for a 1+ year runtime)

Also, is consumption of the Jeenode USB significantly higher than the SMD version?
I had a brief look at ESP8266 boards (which are too power hungry for my needs) and read that the regulator and UART are responsible for most power drain during sleep there.
Does the same apply to the Jeenode USB compared to the SMD?

Thanks, Tony

Replies (1)

RE: Jeenode micro as weather monitor - Added by Rolf about 2 months ago

Hi Tony,

DHT22 (temperature and humidity sensor), TMP102 and LM75 (temperature) (the latter two both driven via i2c, the first 1-wire), I use successfully with the Jeenode Micro. One typical configuration is JM with DHT22 connected to DIO1 and AIO1 and a latch relay (5 V, driven by transistors) for switching a room heater on pins DIO2 and AIO2.

You have to be a bit careful with the software, it is not enough that the code fits in ROM, the limited RAM is the bigger problem. Nested function calls (in C) can grow the stack to overflow the RAM size. The compiler doesn't see this, the system is just hanging unexpectely. I had to rewrite some code that i used successfully on the normal jeenode in the way to omit nested function calls.

Concerning power supply I do not have the ideal solution yet. I use the AA power board driven by 2 Mono cells (not very small). The "boost power" version of the JM could be ideal, but the DHT22 has problems with voltages below 3.3V, and the boost power" gives only 3.0V.