4.4 Source Code Overview

Source Code Overview Using the PIC MCU Q10

CPU clock: 32 MHz
Peripherals used:
- ADC²
  - ADC input channel is AIN1: pin RA1
  - ADC reference voltage: V_DD
  - ADC clock: 1 MHz (F_osc/32)
  - ADC Conversion time for single sample: 11.5 μs
- EUSART
  - TX pin RC6
  - Baud rate: 500000, ADC result is sent to the serial terminal
- TMR0:
  - Timer 0 is configured to have 625 μs (1.6 kHz sampling frequency) trigger period, which the ADC in auto conversion trigger uses.
- GPIO
  - pin RB4: Switch S1, to increase ADCC mode
  - Pin RC5: Switch S2, to decrease ADCC mode
  - pin RA4: LED D2
  - pin RA5: LED D3
  - pin RA6: LED D4
  - pin RA7: LED D5

ADC² functions used in example application apart from MCC driver generated

Table 4-3. ADC² Functions Apart From MCC Driver Generated
Function Name	File	Purpose
void ADCC_ComputationModeSetup(uint8_t)	main.c	Calls the mode specific ADC² initialization function
void ADCC_InitializeBasicMode(void)	adcc.c	Initializes ADC² to Basic mode
void ADCC_InitializeAccumulateMode(void)	adcc.c	Initializes ADC² to Accumulate mode
void ADCC_InitializeAverageMode(void)	adcc.c	Initializes ADC² to Average mode
void ADCC_InitializeBurstAverageMode(void)	adcc.c	Initializes ADC² to Burst Average mode
void ADCC_InitializeLPFMode(void)	adcc.c	Initializes ADC² to LPF mode
void ADCC_SetChannel(adcc_channel_t)	adcc.c	Configures the ADC² channel
void ADCC_ProcessResult(void)	main.c	Reads and process the ADC² result
void DataStreamerTxPkt(pkt_t *)	data_streamer.c	Initializes the data streamer packet with (SOF) Start of Frame, ADC² mode, (EOF)End of Frame
void DataStreamerInit(pkt_t *)	data_streamer.c	Transmits data streamer packet through EUSART
void CheckButtonPress(void)	main.c	Reads the status of push button S1 and S2

Table 4-4. Computation Mode: Associated Number and LED
Computation Mode	Computation Mode Number in Data Visualizer	LED Illuminated
Basic	1	All LEDs: D2,D3,D4,D5
Accumulate	2	D2
Average	3	D3
Burst Average	4	D4
LPF	5	D5

The ADC² is configured in the adcc.c in the project folder. Below are the mode specific functions defined in adcc.c which are used in this application.

void ADCC_InitializeBasicMode(void);
void ADCC_InitializeAccumulateMode(void);
void ADCC_InitializeAverageMode(void);
void ADCC_InitializeBurstAverageMode(void);
void ADCC_InitializeLPFMode(void);

Note: In adcc.c the ADCC_Initialize() function is a driver generated function and called in SYSTEM_Initialize() as part of standard driver initialization.

Upon power-up, the default mode is the Basic mode, which calls the initialization routine ADCC_InitializeBasicMode() configured for the Basic mode. The computation mode number will be configured to 1 to represent it in the Data Visualizer and all LEDs are turned on. When S1 push-button is pressed, the computation mode will be increased and it will initialize the ADC with the selected mode. Different LEDs are turned on depending on selected computation mode. The Computation mode and Associated Computation mode number and LED illumination are shown in Table 4-4.

The interrupt, regardless of threshold test results, is configured in ADCON3 registers (ADTMD[2:0] = 7). When ADC result is ready, the ADTIF flag will be set and the ADC result and selected computation mode number will be sent to the Data Visualizer over EUSART.

The ADTIF flag is set on every ADC conversion for the Basic and Accumulate modes. For the Average, Burst Average, and LPF modes it will be set after accumulating configured n number of samples. In this example source code, it will be set after accumulating 32 samples (as ADCRS is configured to 5).

AN2801

4.4 Source Code Overview