The bootloader firmware is included with the application software on the Downloads page. Once the host software has been installed the bootloader firmware will be in a folder called firmware in the application directory. The unit can then be updated to the latest version, 1.06a, with the downloader utility.

The project is based on a PIC18F4550 microcontroller from Microchip. In order for the unit to operate it will need to be programmed with the firmware code that I have written. This can be done with one of the programmers and software programs mentioned below.

Pic Programmers

The microcontroller used in the controller will obviously need the firmware to be programmed into the unit to make it functional. There are a number of different ones that can be made at home.

This is the first programmer that I built and it works fairly well on a standard com port, there have been problems reported using USB to Serial convertors. JDM Programmer

For those wanting to try a parallel port version the following might be worth looking at PPWIN Pic Programmer.

The two that I am currently using are the Pickit2 and ICD2 programmers from Microchip themselves. If you intend to be using the programmer a lot then I recommend the Pickit2. The newer Pickit3 has been released but it does not have as many features as the older version 2 model. They can be purchased fro about $35 or made oneself. The only drawback with a DIY model is that once again you will need another programmer to flash the firmware into the Pic for the first time.

You will also need some sort of PC software to do the actual programming of the firmware into the PIC program memory. The two that I have found to be the best are IC-Prog and PICPgm, with the latter being my favourite of the two.


Version 1.06a   24 April 2011

  • Dew point calculation would report the wrong value during the next update after saving parameters to eeprom.
  • The current limiting routine would react too fast, causing the output to shut down prematurely. A small delay is now used to filter out any current spikes when the load is first driven by the FET.

Version 1.06     16 April 2011

  • Updated Humidity calculation routine to average out the value over a number of readings.

Version 1.04     13 March 2011

  • Added bootloader routine.




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