3.2.2 ADC with Computation

• Add ADC to the project

• Configure:

  1. The ADCx as described in the example.

  2. Any other peripherals or pins needed for the use case.

• Generate the code

• Add the code snippet(s) to the application code

• Program the board

• Device Resources:

  1. Add ADC

  2. Add UART

• Configuration:

• ADC, Clock Settings:

  1. Clock Pre-Scaler: Check ADC Clock (Hz) < 2 Mhz.

• ADC, Hardware Settings:

  1. Left Adjust Result: No.

  2. Reference select (if no separate VREF component): Select based on analog input (VDD is a good default).

• VREF

  1. Enable Force ADC Voltage Reference: Yes.

  2. ADC Voltage Reference Source: Select based on analog input (VDD is a good default).

• UART:

  1. UART Dependency Selection: Select the UART connected to Serial/CDC port.

  2. Redirect STDIO to UART (for printf support): Yes.

• System > Pins, for all pins check board schematics:

  1. Pin Grid View: Select an ANx.

  2. Pins: Input/Sense Configuration [ISC]: AIx pin (Digital Input buffer disabled).

  3. Pin Grid View: Select pin for UART Transmit - Tx.

  4. Pin Grid View: Select LED pin as output.

  5. Pins: Rename Custom Name to "LED".

#include "mcc_generated_files/system/system.h"
#include <util/delay.h>

int main(void)
{
    adc_result_t adcResult;
    SYSTEM_Initialize();

    while(1)
    {
        adcResult = ADC0_GetConversion(ADC_MUXPOS_AIN4_gc);  //Check the schematic for your board
        LED_Toggle();
        printf("ADC result is: %2d\r\n", adcResult);
        
        _delay_ms(100); 
    }
}

• ADC conversions are triggerd by a timer overflow callback, where the Data Streamer variables, adcResult and adcSampleCount, are updated.

• After each ADC conversion a LED is toggled and SEND_FRAME is set to true, so that a frame is sent to the Data Visualizer from the main while loop.

• Timer Use Case: 100 ms Timer

• Data Streamer Use Case: Send Frames at a Period Set by the Timer

• Device Resources:

  1. Add ADC

  2. Add Data Streamer

  3. Add Timer/Counter A (TCAx)

• Configuration:

• ADC, Clock Settings:

  1. Clock Pre-Scaler: Check ADC Clock (Hz) < 2 Mhz

• ADC, Hardware Settings:

  1. Left Adjust Result: No.

  2. Reference select (if no separate VREF component): Select based on analog input (VDD is a good default).

• VREF:

  1. Enable Force ADC Voltage Reference: Yes

  2. ADC Voltage Reference Source: Select based on analog input (VDD is a good default).

• TCAx:

  1. Clock Selection: System Clock/x => Select so possible period > needed

  2. Requested Timeout(s): 0.1 (100 ms).

  3. Enable Overflow Interrupt: Yes

• Data Streamer:

  1. UART Dependency Selection: Select the UART connected to Serial/CDC port.

• Data Streamer Table:

  1. uint16_t adcResult

  2. uint8_t adcSampleCount

• System > Interrupt Manager

  1. Global Interrupt Enable: Yes

• System > Pins, for all pins check board schematics:

  1. Pin Grid View: Select an ANx.

  2. Pins: Input/Sense Configuration [ISC]: AIx pin (Digital Input buffer disabled)

  3. Pin Grid View: Select pin for UART Transmit - Tx.

  4. Pin Grid View: Select LED pin as output.

  5. Pins: Rename Custom Name to "LED".

#include "mcc_generated_files/system/system.h"

/* Create a pointer of the type TMR_INTERFACE and assign it to the address of the TCA0_Interface TMR_INTERFACE struct.
This enables us to access the portable API interface, which ensures changing the peripheral instance of the timer runs on is easy. */
const struct TMR_INTERFACE *Timer = &TCA0_Interface;
volatile bool SEND_FRAME = false;

void Timer_Callback_100ms(void){
    DataStreamer.adcResult = ADC0_GetConversion(ADC_MUXPOS_AIN4_gc); //Get the conversion result
    DataStreamer.adcSampleCount++;
    LED_Toggle();
    SEND_FRAME = true;
}

int main(void)
{
    SYSTEM_Initialize();
    
    DataStreamer.adcSampleCount = 0;
    DataStreamer.adcResult = 0;
    
    Timer->TimeoutCallbackRegister(Timer_Callback_100ms);
    
    while(1)
    {
        if(SEND_FRAME){
            WriteFrame();
            SEND_FRAME = false;
        }
    }
}

• ADC, Clock Settings:

  1. Sample Accumulation Number: 16 (then try with 64)

void Timer_Callback_100ms(void){
    DataStreamer.adcResult = ADC0_GetConversion(ADC_MUXPOS_AIN4_gc); 
    DataStreamer.adcResult = DataStreamer.adcResult >> 4;      //Bit shift by 4 for >= 16 accumulated samples
    DataStreamer.adcSampleCount++;
    LED_Toggle();
    SEND_FRAME = true;
}

• Device Resources:

  1. Add ADC

  2. Add Real Time Counter (RTC)

  3. Add Data Streamer

• ADC, Hardware Settings:

  1. Left Adjust Result: No.

  2. Reference select (if no separate VREF component): Select based on analog input (VDD is a good default).

• ADC, Interrupt Settings:

  1. Window Comparator Interrupt: Yes.

• ADC, Window Settings:

  1. Window Comparator Mode: Outside Window.

  2. Enable IRQ on Conversion Satisfying Window Criteria: Yes.

  3. Window Comparator High Threshold(V): 2.5(V).

  4. Window Comparator Low Threshold(V): 1(V).

• VREF

  1. Enable Force ADC Voltage Reference: Yes

  2. Select based on analog input (VDD is a good default).

• RTC, Hardware Settings:

  1. Period (s): 0.05(s).

• RTC, Interrupt Settings:

  1. Overflow Interrupt Enable: Yes.

• Data Streamer:

  1. UART Dependency Selection: Select the UART connected to Serial/CDC port.

• Data Streamer Table:

  1. uint16_t adcResult

  2. uint8_t adcWindowCount

• System > Interrupt Manager

  1. Global Interrupt Enable: Yes

• System > Pins, for all pins check board schematics:

  1. Pin Grid View: Select an ANx.

  2. Pins: Input/Sense Configuration [ISC]: AIx pin (Digital Input buffer disabled)

  3. Pin Grid View: Select pin for UART Transmit - Tx.

  4. Pin Grid View: Select LED pin as output.

  5. Pins: Rename Custom Name to "LED".

#include "mcc_generated_files/system/system.h"

volatile bool SEND_FRAME = false;

void Window_Callback(void){
    LED_SetLow();
    DataStreamer.adcResult = ADC0_GetConversionResult();
    DataStreamer.adcWindowCount++;
    SEND_FRAME = true;
}

void RTC_Callback(void){
    ADC0_StartConversion(ADC_MUXPOS_AIN4_gc);
}

int main(void)
{
    SYSTEM_Initialize();
    RTC_SetOVFIsrCallback(RTC_Callback);
    ADC0_RegisterWindowCallback(Window_Callback);
    
    DataStreamer.adcResult = 0;
    DataStreamer.adcWindowCount = 0;

    while(1)
    {
        if(SEND_FRAME){
            WriteFrame();
            LED_SetHigh();
            SEND_FRAME = false;
        }
        
    }
}

• Device Resources:

  1. Add EVSYS (Event System)

• ADC > Hardware Settings:

  1. Positive Input Selection: ADC input pin x //Select based on your schematics

  2. Start Event Input Enable: Yes.

• RTC > Hardware Settings:

  1. Overflow Interrupt Enable: No.

• EVSYS Configuration:

  1. GENERATORS: RTC_OVF -> CHANNELS: CHANNEL0

  2. USERS: ADC0START -> CHANNELS: CHANNEL0

#include "mcc_generated_files/system/system.h"

volatile bool SEND_FRAME = false;

void Window_Callback(void){
    LED_SetLow();
    DataStreamer.adcResult = ADC0_GetConversionResult();
    DataStreamer.adcWindowCount++;
    SEND_FRAME = true;
}

int main(void)
{
    SYSTEM_Initialize();
    ADC0_RegisterWindowCallback(Window_Callback);
    
    DataStreamer.adcResult = 0;
    DataStreamer.adcWindowCount = 0;

    while(1)
    {
        if(SEND_FRAME){
            WriteFrame();
            LED_SetHigh();
            SEND_FRAME = false;
        }
        
    }
}