This board is the base for my Internet-accessible thermostat which was featured in the September and October 2011 issues of Nuts and Volts Magazine. Click on the magazine image for the September article.
This project is now several years old. In the meantime the Nest and other web-enabled thermostats have become available. The primary purpose of this project was not to build a thermostat but to show how to develop an embedded TCP/IP system using the Microchip tools.
The Microchip development tools have changed with their migration to MPLABX so the files probably won’t compile as is. Even though I still use these boards I haven’t migrated to the new tools yet – I have a WIN-XP system with the old software I use for this. I still have PCBs – contact me if you want some.
- Microchip PIC24HJ128GP204 40 MIPS microcontroller.
- Microchip ENC28J60 10-BaseT Ethernet interface.
- SST (now Microchip) Serial Flash memory .
- Microchip 25AA02E48 MAC address chip provides universally unique MAC address.
- MAX3232 serial interface provides 2 serial ports.
- 3.5mm TRS (stereo) jack provides access to one serial port.
- 2.1mm Power Jack for connecting a regulated 5-volt power supply.
- Onboard voltage regulator provides 3.3V to the components.
- RJ45 MagJack connector for Ethernet connection via CAT-5/6 cable.
- 4 8-pin 0.1” pitch headers provide access to 5V, 3.3V, Gnd, MCLR, second serial port and 26 I/O lines. Of the on-board peripherals, only SPI1 and Timer1 are reserved, all others are available.
- ICSP programming support.
- Pads for adding a 32khz watch crystal for RTCC support.
- While the MagJack has LED link and activity indicators, additional LEDs on the board makes them more visible.
- Pads for 0-ohm resistors for connecting the second serial port.
- On-board power indicator.
- Test point for measuring current at the 3.3V rail.
- All on a 3.5” by 2” board.
Documentation and Resources
The experimenter board includes detailed instructions for modifying and compiling the Microchip TCP/IP Demo App. Portions of code that are unique to the board are included as well. Please note that you must download and install the Microchip MPLAB IDE, C30 compiler and Application Libraries to make changes and compile the application. Links and version numbers are included in the document, and below.
The manual can be found here. The latest update is 20 September 2011. I will be updating this as I get feedback from readers.
Board-specific portions of the code described in the manual are here.
The bill of materials for both the TCP/IP Experimenter board and the Thermostat can be found here.
Microchip download sites can be found here:
- MPLAB IDE – development environment which is required for managing projects.
- Compiler for PIC24 – requires registration and login. The free or evaluation version will work for this project. 2013 update: this link is broken – the C30 compiler has been replaced by MPLABX and the XC16 compiler
- Application Libraries – these include the TCP/IP stack. Also download the help files on this page. 2013 update: these libraries are re-organized as part of the move to MPLABX.