Smallest Heatermeter?


 
F

Fredrik O

New member
I've put together a light version of the Heatermeter using an Arduino Pro Mini (3.3 V, 8 MHz) connected to an HLK-RM04 (32 MB) as the wifi interface:

  • Size: 70x50x35 mm (2.8X2.0x1.4 inch)
  • Full Heatermeter 4.0 functionality except what is noted below
  • Full Linkmeter wifi interface including AVR firmware update
  • 2 probe inputs (pit and food1)
  • Servo output only (no blower needed for my low and slow using my slightly leaky Weber Kettle)
  • No display
  • Remote only configuration
  • 5 V supply

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Nice work! Yeah the size of the HeaterMeter is almost entirely dictated by the edge space required for all the connectors and the fact that I don't want to have wires coming out of the top or bottom. If you just need the essentials, you can really slim it down it appears.
 
Nice work. can you provide any more details on the wiring? I'm interested in setting up my Arduino Uno for a heatermeter, but I'm not sure what components are necessary. Or if I can just flash the Uno from a PC with the Arduiono software.
 
Fredrik,

I saw in one of your other post you bought a 32mb version. Where did you order if from? Have a link?

Jeff
 
Jeff,

It should be possible to use the Uno as stand alone. However, I would be careful interfacing it with the HLK-RM04 as the Uno runs at 5V and the HLK-RM04 logics runs at 3.3 V. Furthermore, the 3.3 V version of the Arduino Pro Mini operates at 8 MHz which makes it necessary to recompile the Heatermeter code in order to get the right timing on, e.g., the serial communication (the AVR on the original Heatermeter runs at 16 MHz).

The wiring I use is a subset of Bryan's 4.0 version (please refer to the schematic http://capnbry.net/linkmeter/pcb/hm-4.0/HeaterMeterPI.png):
The two probes (food1 and pit) with their 10 k resistors are connected to ADC4 and ADC5, respectively and the servo control line is connected to PB0 and the servo 5 V supply comes directly from the 5 V connector. The 3.3 V supply for the Arduino is obtained from the HLK-RM04 that has a 300 mA 3.3 V source.
The serial connection between HLK-RM04 and the Arduino is via the HLK's TX2/RX2 (UART) and the AVR flashing is done by emulating an SPI using GPIOs 0, 1, 2, and 14 on the HLK (the SPI bus is not exposed on the HLK unfortunately).

I have a schematic drawing of the setup on my todo list and I'm about to put the required software patches on Github.

I bought the HLK-RM04, 32 MB, via Alibaba in China: http://www.alibaba.com/product-detail/uart-wifi-module-with-8m-flash_1956679555.html

/Fredrik
 
Wow, I'm impressed. I actually was about to build a bunch of full heatermeters, but I really only just need a WiFi temp gauge since everyone I'm building for just wants them for pellet grills. These might be easier and less expensive.

Would it be easy to make it work with 4 probes?

Thanks!
 
Aaron Morris said:
Wow, I'm impressed. I actually was about to build a bunch of full heatermeters, but I really only just need a WiFi temp gauge since everyone I'm building for just wants them for pellet grills. These might be easier and less expensive.

Would it be easy to make it work with 4 probes?

Thanks!
Click to expand...

Just remember, you're going to end up being their tech support guy if/when things go wrong! It's for this reason that I never have a problem with tinkering / experimenting with my own stuff, but always recommend that friends & others go with a more streamlined approach, since I don't want to be on the hook for their problems :)
 
True. I am thinking this would be a great small version for other things. I wonder how tough it would be to make a PCB to mount everything on and get a small printed case for.
 
What I would do is use the v4.2.4 PCB and remove the $10 LCD from the mouser parts list. You could modify the 3D case files to fill in the holes for the LCD and multi direction button.
 
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