Having trouble with SERIN command and MAX6675

[mackrackit]

Is the thermocouple a K type?
The code given in the link I gave works.
Check the hardware. Bad connections or backwards connection on the thermocouple or wrong type will cause problems.

[emerson]

Is the thermocouple a K type?
The code given in the link I gave works.
Check the hardware. Bad connections or backwards connection on the thermocouple or wrong type will cause problems.

Both the thermocouples I have are K type and are connected properly. The ground lead on the thermocouple is tied to ground as well as the negative input on the MAX6675 as demonstrated in the datasheet. I did a continuity test on all wires coming from the chip and they're all good.

[emerson]

is the code you gave specifically for the 16f630?

[mackrackit]

No. The code shows how to use the MAX chip.

[emerson]

i found in this post (http://www.picbasic.co.uk/forum/show...1178#post71178) that you stated you need a temperature
reference for every time the wire material from the thermocouple changes.

Anyplace the wire material changes you need a reference temperature and calcs. A couple exceptions here and there though.

I had copper wire soldered to the terminals on my thermocouple. I disconnected the copper wires but it didn't help

[mackrackit]

Do you have pin #6 (CS) on the MAX6675 pulled low? I use a 10K to the zero rail on mine.

[aratti]

MAX6675 need more than 200 millisecs for the temperature convertion. You are polling too fast so you don't get any response. Place a delay of 250 msecs to allow convertion.

edit:My note was reffered to code seen in post#5. I just see that you added delay 500 in your code in post #7, so my answer is obsolete.
My new suggestion are :

add INCLUDE "modedefs.bas" on top of your code
and modify your SHIFTIN command adding:

shiftin MXSO, MXSCLK, MSBPRE, [MXTemp\16] 'read the data to MXTemp

and see if it works.



Al.