![]() I use battery terminals from Keystone available from RS Components, positive and negative. The wire out of the battery box was cut, shorted and stuffed away inside the box. I then drilled a hole in the battery box where the sensor can protrude and a small hole for the LED to shine through. Next I clipped the legs of the DS18B20 until about 5mm remained and soldered it to the 3x pin header on the AAduino. ![]() There is some room for that kind of modification without damaging the module. Update, the RFM69C will fit without modification. Since the RFM69C is somewhat wider than an AA battery I used a file to make it slightly narrower. Running at 4Mhz would be more suitable but I will see how well the node performs when the batteries are draining out. I have fused the 328 to brown out at 1.7V which is a bit out of spec at 8Mhz and slightly below what the RFM69C needs. It runs at 8Mhz to allow for greater life span since the CPU can run at a lower voltage. There is room for two DS18B20 temperature sensors and an indicator LED. It is powered by an ATMega328p and is fitted with an RFM69C companion. The AAduino is an wireless Arduino clone the size of an AA battery with Keystone battery terminals rotated 180° to act as positive and negative terminals. I needed to shrink the radio node, and the AAduino was born. I did have a set of standard eBay AA battery holders and looking at the 3x variant it occured to me. That search came up disappointingly, and surprisingly, short. This leaves me with finding off the shelf project boxes with a compartment for 2x AA batteries and the “radioduino” (and in an acceptable form factor). I could of course 3D print a case for the Tin圓28 but I have limited access to 3D printers and do not feel I have the time to explore that exciting part of the maker world just yet. Now I wanted a more slim ISM node as my setup with a Tin圓28 on a breadboard is not very “deployable”. I have been using Nathan Chantrell’s Tin圓28 for quite some time as my swiss army knife ISM radio node. Update: you can now order the AAduino PCB from and get a Commadorable 64 bonus PCB for free. News: the crowd sourcing campaign for the AAduino will start soon, sign up at CrowdSupply to be notified! The specs have been beefed with an STM32L0 cpu and the temperature sensor is now an industrial grade TMP102. More news: read all about the new AAduino Zero. ![]() The BOM should add up to about the price of lunch.Ĭode and schematics on Github as always. Oh, and the ESP12F talking to an RFM69CW. The rest of the BOM consists of 0603 resistors and capacitors, an LM1117 3.3V regulator and a SOT23 P-mosfet for driving the 0603 LEDs. The push button currently serves no purpose but the plan is to perform a “master reset” of the device using this button. The type-A right angle 90 degreee USB connector and 3圆x2.5mm push button can be found for little money on eBay. I ported Andreas Heßling’s STM32 RFM driver to the lovely ESP Open RTOS, my swiss army knife for ESP8266 development. The MQTT server IP and RFM69 network information is hard coded into the binary. Well three LEDs as I made a mistake on the ground plane. Packets are posted in hex followed by the RSSI value: espism-5ccf7f147cd Hello from 172.16.3.120Įspism-5ccf7f147cd 016340630001000000c375b642Ī set of four LEDs indicate received packets. Currently it works as an ISM sniffer posting the received packets on the MQTT topic espism.
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