I need help with writing the assembly code for a PID temperature control using a pic 16f877a and rs232 interface to a external temp sensor.
I have already written and tested the rs232 interface code which communicates with the external temp sensor unit. The problem I am having is I am commited to using an 8 bit pic which until now has not been an issue. I wrote and tested code which works perfectly up to 256 degrees f but as you can imagine I had rollover issues with higher temp values due to the 8 bit issue. I have written and tested code which will count by tens up to 100 and then set flags before advancing, burning each 10 degree setpoint to eeprom. This works up to the limit of 550 degrees but since the temperature profile is s shaped I am having tracking problems in the non-linear areas on each end of the scale which cause erroneous setpoints to be recorded to eeprom and thermal runaway on the high temp end. I am running out of time to debug this module and I need to move on to other more manageable section in succession to complete this project.
If anyone can help I would rather send code and talk over the phone since I am a very slow typist. Please contact me if interested ASAP. Thankyou