DMA with ADC for continuous sampling in Embedded C - Mini Project: Build & Apply

DMA with ADC for Continuous Sampling

📖 Scenario: You are working on a microcontroller project where you need to read analog sensor data continuously without blocking the CPU. To do this efficiently, you will use the ADC (Analog-to-Digital Converter) with DMA (Direct Memory Access) to transfer data automatically to memory.This setup is common in real-time sensor monitoring systems like temperature logging or audio signal processing.

🎯 Goal: Build a program that configures the ADC and DMA to continuously sample analog data into a buffer without CPU intervention. You will set up the data buffer, configure DMA parameters, start ADC with DMA, and finally print the sampled data.

📋 What You'll Learn

Create a buffer array to store ADC samples

Define the number of samples to collect

Configure DMA to transfer ADC data to the buffer continuously

Start ADC with DMA for continuous sampling

Print the collected ADC samples

💡 Why This Matters

🌍 Real World

This technique is used in embedded systems to read sensors continuously without slowing down the main program. It helps in applications like environmental monitoring, motor control, and audio processing.

💼 Career

Embedded developers often use DMA with ADC to optimize performance and reduce CPU load in real-time systems.

1

Create ADC data buffer and sample count

Create an integer array called adc_buffer with size 10 to hold ADC samples. Also, create an integer variable called num_samples and set it to 10.

Embedded C

# Create adc_buffer array and num_samples variable
# Your code here

Need a hint?

Think of adc_buffer as a container to hold 10 numbers from the ADC.

2

Configure DMA for ADC data transfer

Create a struct variable called dma_config and set its source_address to &ADC->DR, destination_address to adc_buffer, and transfer_size to num_samples. Assume the struct has these fields: source_address, destination_address, and transfer_size.

Embedded C

int adc_buffer[10];
int num_samples = 10;
// Configure dma_config struct with source, destination, and size
# Your code here

Need a hint?

DMA needs to know where to read from, where to write to, and how many samples to transfer.

3

Start ADC with DMA for continuous sampling

Call the function ADC_Start_DMA with arguments adc_buffer and num_samples to start ADC with DMA in continuous mode.

Embedded C

int adc_buffer[10];
int num_samples = 10;

struct DMA_Config {
    volatile int *source_address;
    int *destination_address;
    int transfer_size;
} dma_config;

dma_config.source_address = &ADC->DR;
dma_config.destination_address = adc_buffer;
dma_config.transfer_size = num_samples;

// Start ADC with DMA
# Your code here

Need a hint?

This function tells the ADC and DMA to begin sampling and transferring data automatically.

4

Print the ADC samples

Use a for loop with variable i from 0 to num_samples - 1 to print each value in adc_buffer using printf in the format: "Sample i: value\n".

Embedded C

int adc_buffer[10];
int num_samples = 10;

struct DMA_Config {
    volatile int *source_address;
    int *destination_address;
    int transfer_size;
} dma_config;

dma_config.source_address = &ADC->DR;
dma_config.destination_address = adc_buffer;
dma_config.transfer_size = num_samples;

ADC_Start_DMA(adc_buffer, num_samples);

// Print all samples
# Your code here

Need a hint?

Loop through the buffer and print each sample with its index.