1. Jordan Barry Victor Brzeski
TM4C123g ADC Peripheral
Jordan Barry
Victor Brzeski

2. Brief Overview
Samples, and converts an analog voltage to a digital value
Used frequently in sensor measurement
Conversion triggered via SWI or HWI

3. TM4C123g MCU’s ADC Two ADC modules 12-bit Precision
12 Input Channels each
12-bit Precision
Maximum sample rate of 1 million samples/second
FIFO buffers
Trigger Control
SWI
Timers
Analog Comparators
PWM interrupts
GPIO Interrupts

4. Hardware Interface Results are bound via VREFP and VREFN
These are internally connected to analog supply voltage/GND
Sample Averaging Circuit
Averages 4 samples during conversion
Useful for noisy signals
Differential Sampling
Difference of 2 channels
Internal Temperature Sensor
Can be sampled for chip temp

5. TI API Example
Using the TI API functions listed at: TI's Website we use their short example given:
Enable the channel desired for when trigger occurs
Trigger sample sequence (Event Occurs eg. SWI, HWI)
Wait for ADC conversion to complete (Semaphore)
Read value from ADC result FIFO registers

6. Code Provided by TI

7. Triggers
- \b ADC_TRIGGER_PROCESSOR - A trigger generated by the processor, via the
//! ADCProcessorTrigger() function.
//! - \b ADC_TRIGGER_COMP0 - A trigger generated by the first analog
//! comparator; configured with ComparatorConfigure().
//! - \b ADC_TRIGGER_COMP1 - A trigger generated by the second analog
//! - \b ADC_TRIGGER_COMP2 - A trigger generated by the third analog
//! - \b ADC_TRIGGER_EXTERNAL - A trigger generated by an input from the Port
//! B4 pin. Note that some microcontrollers can
//! select from any GPIO using the
//! GPIOADCTriggerEnable() function.
//! - \b ADC_TRIGGER_TIMER - A trigger generated by a timer; configured with
//! TimerControlTrigger().
//! - \b ADC_TRIGGER_PWM0 - A trigger generated by the first PWM generator;
//! configured with PWMGenIntTrigEnable().
//! - \b ADC_TRIGGER_PWM1 - A trigger generated by the second PWM generator;
//! - \b ADC_TRIGGER_PWM2 - A trigger generated by the third PWM generator;
//! - \b ADC_TRIGGER_PWM3 - A trigger generated by the fourth PWM generator;
//! - \b ADC_TRIGGER_ALWAYS - A trigger that is always asserted, causing the
//! sample sequence to capture repeatedly (so long as
//! there is not a higher priority source active).

8. Interrupts
//! - \b ADC_INT_SS0 - interrupt due to ADC sample sequence 0.
//! - \b ADC_INT_SS1 - interrupt due to ADC sample sequence 1.
//! - \b ADC_INT_SS2 - interrupt due to ADC sample sequence 2.
//! - \b ADC_INT_SS3 - interrupt due to ADC sample sequence 3.
//! - \b ADC_INT_DMA_SS0 - interrupt due to DMA on ADC sample sequence 0.
//! - \b ADC_INT_DMA_SS1 - interrupt due to DMA on ADC sample sequence 1.
//! - \b ADC_INT_DMA_SS2 - interrupt due to DMA on ADC sample sequence 2.
//! - \b ADC_INT_DMA_SS3 - interrupt due to DMA on ADC sample sequence 3.
//! - \b ADC_INT_DCON_SS0 - interrupt due to digital comparator on ADC sample
//! sequence 0.
//! - \b ADC_INT_DCON_SS1 - interrupt due to digital comparator on ADC sample
//! sequence 1.
//! - \b ADC_INT_DCON_SS2 - interrupt due to digital comparator on ADC sample
//! sequence 2.
//! - \b ADC_INT_DCON_SS3 - interrupt due to digital comparator on ADC sample
//! sequence 3.

9. Logic flow – Interrupt Based
Set ADC trigger to a SWI, at a specific sampling period
Eg. ADC_TRIGGER_TIMER via RTOS
Configure ADC to interrupt when ADC sample sequence is complete
Eg. ADC_INT_SS0
Sample values from FIFO Register
Read from SSFIFO3 Register
Send values to PID or bang/bang algorithm
Adjust motor duty cycle

10. Questions
Please