Easytherm is a tool that helps making curves from a few calibration points for an NTC temperature sensor.
The coolant and manifold air temperature sensors are (in 99.9% of cases) NTC type. The ExhaustGasTemp sensor can never be an NTC type.
Easytherm files are located in the files section of the Megasquirt group at http://groups.yahoo.com/
Steps:
- if possible, 3 calibration points must be measured. Say, at sensor temperatures
- 95C warmed engine
- 20C cold engine
- and 0C (a cup of icy water before installing the sensor to the final location)
- Check pullup resistor values, v3.2 has 2.7k resistor instead of 2.49k used in megasquirt. If incorrect pullup value is used, there will be a few degrees error in the lower temperature range.
- .inc file can be generated with easytherm, or other means. This is a very simple function, a few lines.
- note: (AFAIK) MSToolsII can also be used to create .inc files
- but: the upload function in MSToolsII is NOT compatible with GenBoard. GenBoard's has it's own firmware generation and upload procedure. The .inc files need a slight automatic formatting (into .c files) with the following commands, so that they will actually be used in the firmware build process:
- perl bin/inc2tbl NAME-OF-THE-MAT-INC-FILE > etc/airdenfactor.c
- perl bin/inc2tbl NAME-OF-THE-CLT-INC-FILE > etc/thermfactor.c
- See GenBoard/FirmWare for firmware compiling and uploading
Developer TODO - to make some of the above few simple steps automagic:
- add makefile entries, so inc2tbl is automagically run if etc/airdenfactor.inc is newer than etc/airdenfactor.c
- likewise for etc/thermfactor.c
- generate etc/airdenfactor.inc from simple text-based etc/airdenfactor.cal textfile of a few calibration points (containing Celsius => whatever)
- update the above steps to match