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After making the wearable MSP430 for Halloween this year I was requested to make more for a children's dance group. I have a question, but first some background. This is the latest version: Everything works fine. I use an adapter with pogo pins to program it as shown in the photo. There are three LEDs on the PCB, a push button switch for the user, and more accessible pins than the previous version. Parts are TSSOP and 0805 SMD. Snap fasteners and stainless thread can be used to connect it to LEDs on the costume. A CR2032 coin cell is used to power it (coin cell holder is on the backside of the PCB). So far that has been sufficient and the light weight and inconspicuous nature has been advantageous for the small children it is intended for. Now a new upgrade has been requested... add a radio so that multiple units can be synched and/or controlled offstage. Here is a rough list of requirements: must be inexpensive - current materials for 10 units is less than $5. I want to keep it under $10. keep SMD parts large enough to be hand soldered keep using CR2032 (rated 3V and 225 mAH) The MSP430G2553 and LEDs are currently using no more than 20 mA on average - to be safe assume 40 mA Unit needs to run at least half an hour on fresh batteries Unit needs reliable radio reception at 10m with clear line of sight Unit will need to receive only - no transmission. Reception updates required close to continuously - say every 100 ms keep PCB to the same size - 40mm/1.6" diameter needs to be programmable in Energia I have a fair amount of time - 6 months to get it working I have looked at several different radios but the two that I have experience with are the nRF24L01 and CC2650. I am ruling out the CC2650 due to cost. There is a small version of the nRF24L01 that is shown below for scale along with the more commonly seen version: I think I can shift things around and make this fit. Connection is by the castellated edge facing forward on the photograph. The datasheet states 13.5 mA RX at 2Mbps air data rate. That is in the range of what I have seen as well so it looks like it would meet the requirements. Here are my questions: 1) Is there another radio I should be looking at? Maybe one made by Hope. 2) I have no design experience with radios but could I use an off the shelf design and put the radio, bits, and PCB trace antenna on the PCB myself? I would probably have to give on the 0805 parts size criteria. 3) Any other thoughts, comments, and suggestions appreciated. This will be an open source design and anyone who wants to contribute or have the design is welcome EDIT: the material cost is on a per unit basis