Wireless Weather Sensors
From Makers Local 256
Overview
Designed to be simple to build, low parts cost, and low maintenance.
Needs:
- Wirelessly transmit temperature and relative humidity to a main unit.
- Run off a single AA, two AA, or a 9v battery
Wants:
- Two pins who's grounded status could be reported (think a door sensor, or something)
- Two pins that could be set to send 3.3v or 5v to run an relay
- Thermostat control?
Status
In progress
- Identify all components
- Need opticron's help
- Determine if any of the SHTx line would be better and cheaper than the DHT22
- Figure out any additional components, pressure?
- Identify an AVR
- Validate with someone else
- Determine total pin count needed for AVR
- Identify cheapest AVR
- Order components and AVR
- Breadboard a prototype
- Design PCB
- Need crashcart's or mog's help
- Order or print prototype PCBs
- Need mog's help
- Build first test prototype
Operation
- Each unit will power up and listen for the sync signal from the master unit.
- Once they get the sync signal, they listen for any other already established units to send their data.
- Then they locate the next spot in the time slots.
- Something about collisions
- Something about the master allocating timeslots dynamically
- Something about filling in blank timeslots.
Assembly
Slave
- A slave has all of the parts below
Master
- A master has all of the same parts
- A master also piggybacks on an openmesh router or 802.11 device of some sort.
Parts
Name | Price for 10 units | AVR pins required | Link | Alt Link |
---|---|---|---|---|
RFM22B-S2 Wireless Transceiver | $4.40 | 4(SPI) | http://www.hoperf.com/rf_fsk/RFM22B.htm | |
DHT22 Humidity and Temperature Sensor | $8.96 | 1 (i think) | http://www.sparkfun.com/products/10167 | |
BMP085 - Pressure Sensor | ? | ? | ? | |
Battery case | ? | ? | ? |
AVR possibilites:
Model | I/O Pins | Price per 10 | Link |
---|---|---|---|
ATTINY84 | 12 | $3.01 | http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=ATTINY84-20PU-ND |
ATTINY4313 | 18 | $2.80 | http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=ATTINY4313-PU-ND |