Added an interface to controll LEDs (e.g. active LED, error LED).
Initializing the LEDs and turning the 'active' LED on when the PID controller is in operation.
Initializing buttons and using one of the buttons to turn on and off the PID control.
Added a serial interface command to read out the ADC value of temperature sensor 1.
Added lookup tables for temperature to ADC conversions with Pt1000 sensors using the ADS1248 ADC.
Added conversion of ADC value to temperature when reading out the sensor through the serial interface and added two commands to read out the ADC value directly.
Added a function to select the sensor for the ADS1248 ADC which sends commands to set up the analog multiplexer and the excitation current sources. This function is used in the start conversion fuction. In order to make the ADC settle fast enough to allow for 16 tasks per second the ADC conversion rate is set to 40 SPS.