Cheap Wireless Node
Overview
Goals
- Microcontroller, RF transceiver and basic power supply (LDO and/or coin cell battery) on a single board
- Good range, UHF 315/433/915 MHz
- Less than $20 retail cost for one, target BoM $7.5
- Several GPIOs and ADCs available
- Part 15 certification
Similar to RadioBlock, but with potentially better range and cheaper. This project is pointless if RadioBlock turns out to be cheap enough or have good enough range.
Sub-1 GHz is for good range, but is more susceptible to industrial interference. 2.4 GHz might be a better choice.
Applications
- Remote sensor node
- Remote control node
- Wireless serial
Parts
nRF24L01+ approach
nRF24L01+ is part from Nordic that does proprietary RF over 2.4 GHz. It's generally cheaper than 802.15.4 alternatives. Modules are available on eBay for $4 for a pair, $13 for a module with PA and LNA or $9 for nRF24LE1, a version with an 8051 microcontroller. RF24Network is a mesh stack for RF24. If these cheap Chinese modules work well, they would satisfy all the requirements for this project.
RF24Network will probably not work on nRF24LE1 because there is no open source C++ compiler for 8051.
Microcontrollers
- ATmega32U4
- ATmega328P
- LPC1114
- ATmega128RFA1 (2.4 GHz)
- ATmega644R212 (?)
- Si1000 series (433 MHz)
Transceiver/RF
Trace antenna? Johanson or TDK combined balun/filter.
RFM12B module?
