After lots of days delay, finally got some time to work on long pending task of making cheap wireless communications with off shelf components.
For wireless communications one can use following standards:
For wireless communications one can use following standards:
- ZigBee
- Bluetooth
- WiFi
Most of the chips are difficult to solder/prototype (as they are BGA/QFN type chips) for part-time/full-time hobbyists. Development/evaluation kits are costly (though one can get some ZigBee SPI-Boards at around 20$). So I was looking at cheaper alternatives that give alternate paths for cheap wireless communications for following type of applications (from Hobbyist perspective):
- Home automation
- Car monitoring system
- Generic monitoring (metering, controls, etc)
For getting cheap wireless device (with Linux OS with good amounts of RAM/Flash-Space!!) I choose OpenWRT/DD-Wrt projects where one can find various hacked WiFi devices which are available cheaply. So I chose DIR-300 as it is available in India (Banaglore) cheaply for Rs.1300/- (~22$).
Idea is to connect a MCU to above WiFi-device via Serial (RS232/USB) and control/monitor the devices/systems. Most of the WiFi devices have Serial ports (one has to solder on the WiFi boad, lots of inputs are available on each successfully-hacked-device). I have developed basic connectivity for Rs232/USB in Linux and USB-Device-Driver support for Microchip-USB devices. So for the DIR-300, I have to use RS232 (as it does not have USB port)
After following the instructions at OpenWRT site, I was able to load kamikaze-OS. Downloaded MIPS cross compiler and successfully tested a TCP-socket based program that talks to PCs via WiFi network and RS232 connectivity to Microcontroller.
I am planning to try following MCUs for this DR-300:
- Microchip's PIC18F2520 (I have other PIC24/PIC18 series chips to try around) -- this MCU costs less than 3$. At present I am trying this with Easypic3 development board.
- Texas Instrument's MSP430 LaunchPad Value Line Development kit -- this eval-board costs around 4.5$. From India you can order from Erstwhile Farnell for approx Rs. 300/-.
- NXP based ARM chip LQFP48-LPC2106 from teamfdi. This eval-board cost around 10$ with 32-bit processor with 128KB Flash/64KB RAM
But there are lots of cheap eval-boards which can be tried.Some of them are:
- STM32 ARM 32-bit Cortex-M3 MCU 128 KB Flash, 8 KB RAM in 64-pin LQFP -- this eval-boards cost around 12$
Will be posting soon about my DIR-300 C based socket program that connects WiFi/RS232.
