More progress with wireless sauna temperature thingy

My original plan was to use a MSP430 based launchpad (cheap!) instead of an Arduino for the sensor part. I had major troubles getting any data to go trough so decided to first try with identical platforms and libraries. That worked so at least I knew that my NRF modules where ok.

I started to look into using the MSP430 based launchpad now, first I had some weird trouble that a simple test worked, then suddenly it didn't and sometimes just a part of the data got trough to the receiver. Digging into the enrf24 and RF24 libraries a bit more I found the reason (enrf24 uses dynamic payload (only!) by default, RF24 doesn't) and connecting my MAX6675 thermocouple amp also made the sending not work if I used a particular pin (I think it was 2.3?) on the launchpad, moving that to 1.4 fixed that issue.

Now it works!


I'm now powering the sensor with a USB power bank and that just wastes energy so next is to make everything as power efficient as I can and power it using a 3V coin-cell.

That should be possible as I can sleep most of the time as the temperature does not change that fast and often anyway.

Perhaps something like:

• Average temperature, say for 3 samples, does not change much: Sleep 30 seconds
• If temperature starts to change, sleep less, say 10 seconds
• If temperature changes rapidly, sleep 5 seconds
• Send temperature only when temperature changes

Comments ?

MSP430 Serial FATAL: cannot open /dev/ttyACM0: Input/output error

Getting this when trying to open the serial port to your MSP430 on a launchpad ?

FATAL: cannot open /dev/ttyACM0: Input/output error

The reason seems to be that a buffer on the serial converter gets full and the chip gets upset and fails.
But you can easily workaround it. Disconnect the serial pins from the "emulator" (why do they call it an emulator in first place, I don't get it, it does not emulate anything) part on the board by removing the jumpers.

Connect the USB cable to your computer and now open the serial device in for example picocom or some other serial app. It should open ok now.

Now put the jumpers back in, you should get your serial output now.

Wireless sauna monitoring system using MSP430

I've been planning, for a long time now, to create a monitoring system to our summer cottage. Features would include monitoring of temperature of air and lake water (the cottage is by a small lake) and why not air moisture and barometric presure just for fun.

Also monitoring the sauna temperature in some inteligent way, for example for informing to add more wood and "Sauna is ready!" signal.

All of this would of course be logged on a SD and some way to view everything, maybe just a 16x2 LCD screen or perhaps something a bit more cool.

Anyway, finally some progress, a wirebundle of a wireless sauna sensor. Basically just a MSP430 launchpad, MAX6675+thermocouple wire and a NRF24 radio.

I'm using energia, sketch will be up soonish on my github.

It seems to be sending, I haven't tried the RX part yet :)