STM32 & MCP3008: Multi-Channel ADC Expansion via SPI

Project Description

This project demonstrates how to interface the MCP3208 12-bit, 8-channel analog-to-digital converter (ADC) with an STM32F103C6 microcontroller using the SPI protocol. The MCP3208 provides high-precision 12-bit resolution with flexible input configuration options, supporting both eight single-ended inputs and four pseudo-differential input pairs. The device operates from 2.7V to 5.5V and communicates via a straightforward SPI interface, achieving sampling rates up to 100 ksps. This integration enables precise multi-channel data acquisition for applications such as sensor interfaces, process control, and battery-operated systems, with real-time data output via UART and full Proteus simulation support.

STM32CubeMX Setup

• MCU Selection: STM32F103C6
• Clock Configuration: 8 MHz HSI
• SPI1 Configuration:

- Mode: Full-Duplex Master

- Prescaler: 16 (500 kHz SPI clock for MCP3208 compatibility)

- CPOL: Low, CPHA: 1 Edge

• GPIO Configuration:

- PA4 configured as Output Push-Pull (Chip Select/Shutdown for MCP3208)

• UART1 Configuration:

- Baud Rate: 115200

- Word Length: 8 bits

- Parity: None

- Stop Bits: 1

• Generate initialization code in STM32CubeIDE.

STM32CubeIDE Setup

Key Functions

• MCP3208 Structure & Initialization

- MCP3208_HandleTypeDef

- Structure containing SPI handler and CS GPIO configuration for device management.

- void MCP3208_Init(MCP3208_HandleTypeDef* hmcp3208);

- Initializes the MCP3208 ADC by configuring SPI interface and CS GPIO pin.

• Single-Ended Input Measurement

- uint16_t MCP3208_AnalogRead(MCP3208_HandleTypeDef* hmcp3208, uint8_t channel);

- Reads single-ended analog value from specified channel (0-7) and returns 12-bit result.

• Differential Input Measurement

- int16_t MCP3208_AnalogReadDif(MCP3208_HandleTypeDef* hmcp3208, uint8_t pair);

- Reads differential analog input from specified channel pair and returns signed 12-bit result.

• Main Loop Logic

while (1)
{
// Read single-ended value from channel 0
uint16_t adc_value = MCP3208_AnalogRead(&hmcp3208, 0);
// Send data via UART
printf("CH0 Value: %d\r\n", adc_value);
HAL_Delay(500);
}

Proteus Simulation

Required Components:

• STM32F103C6 microcontroller
• MCP3208 12-bit ADC
• POT-HG (Potentiometer)
• RES (Resistor, 10kΩ for reference circuits)
• Virtual Terminal (UART)

Connections:

• SPI1: PB3 (SCK) → MCP3208 CLK, PB4 (MISO) → MCP3208 DOUT, PB5 (MOSI) → MCP3208 DIN
• Chip Select: PA4 → MCP3208 CS/SHDN
• Analog Input: Potentiometer output → MCP3208 CH0
• Power: MCP3208 VDD → 3.3V, VREF → 3.3V, AGND & DGND → GND
• UART1: PA9 (TX) → Virtual Terminal RX

Steps:

• Load the.hex file compiled from CubeIDE.
• Run the simulation.
• Adjust the potentiometer to vary the analog voltage on channel 0 (0V-3.3V).
• Observe the real-time 12-bit ADC values (0-4095) on the Virtual Terminal.

That's all!

If you have any questions or suggestions don't hesitate to leave a comment below