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README
max31855.c
max31855.h

README

EP (easy peasy) implementation of MAX31855 library to be used with HI-TECH PICC18.

--Disclaimer and license--
You can do with this code whatever you like, but remember, always give credi where credit is due.
You can not hold me liable for anything this code does or does not do.
Use it at your own risk. If you do not understand what this code is about,
do not even look at it. Be warned, use of this code is sole your responsibility, not mine!
No support is provided in any form.
This is first thing I have ever done on PIC and with PICC18.
--Disclaimer and license end--

How to use it (unless you are scared off by previous section of this README)

1) #include "max31855.h"
2) edit max31855.h and replace MAX31855_CS_LAT and MAX31855_CS_TRIS with definition
   for pin you are going to use as CS
3) somewhere in your code initialize SPI, like for example HW SPI with PICC18 peripherals
   library OpenSPI(SPI_FOSC_64,MODE_01,SMPEND), along the way, read the
   manual of MAX31855, regarding what speed and what type of SPI it talks.
4) setup max31855 library by calling setupMAX31855(ReadSPI). The argument to setupMAX31855()
   function is pointer to the function that reads a byte from SPI, in this case it is PICC18
   HW SPI function ReadSPI. Function has to return unsigned char and have no parameters. Besides
   this function must not touch CS line of MAX31855
5) if everything is correct, you should be able to read your temperature now like this:
   float temperature = readCelsius() please note that temperature is returned in degrees Celsius
   and both negative and positive values are returned. If there is a fault, returned temperature
   is 9999.0, which is way out of working range of the chip and that should serve as a clue to
   you.

Besides reading thermocouple temperature, you can as well read cold junction temperature like
this:
float cjtemperature = readCJCelsius();
And if you manage to hit those dreaded 9999.0 degrees, you can find out what exactly is wrong
with your MAX31855 by reading status of chip like this:
char max_status = readStatus();
if (max_status & SCV_FAULT)
	printf("Your t-couple is shorted to VCC!\n");
if (max_status & SCG_FAULT)
	printf("Your t-couple is shorted to GND!\n");
if (max_status & OC_FAULT)
	printf("You do not have any t-couple! There is open circuit!\n")

I tested my MAX31855 with breakout board from http://www.tautic.com and PIC18F25K20 as found on
Amicus18 board by http://www.myamicus.co.uk/ your mileage will for sure vary as you go.

Good luck, may the force be with you, read the datasheets and read the sources!