SPI (Serial Peripheral Interface)

Explore SPI communication protocol and learn how to interface with SPI devices using the DualMCU ONE board. We’ll guide you through setting up SPI communication and interfacing with SPI devices.

SPI Overview

SPI (Serial Peripheral Interface) is a synchronous, full-duplex, master-slave communication bus. It is widely used to connect microcontrollers to peripherals like sensors, displays, and memory devices. The DualMCU ONE board supports SPI communication, enabling you to interface with a range of SPI devices.

Pinout Details

Below are the SPI pins for the DualMCU ONE board, including GPIO mappings for ESP32 and RP2040.

Fig. 37 SPI ESP32 Pinout Diagram

Fig. 38 SPI RP2040 Pinout Diagram

Table 8 SPI Pin Mappings

Pin	ESP32 GPIO	RP2040 GPIO
SCK	18	18
MISO	19	16
MOSI	23	19
SS	5	17

Caution

ESP32 and RP2040 share certain SPI pins. To avoid conflicts, use only one microcontroller at a time.

SPI Communication Example

Below is a basic example of initializing and using SPI with a Micro SD card in MicroPython:

import machine
import os
from dualmcu import *

# Define SPI pins
SCK_PIN = 18
MOSI_PIN = 23
MISO_PIN = 19
CS_PIN = 5

# Initialize SPI interface
spi = machine.SPI(1, baudrate=100000, polarity=0, phase=0, sck=machine.Pin(SCK_PIN), mosi=machine.Pin(MOSI_PIN), miso=machine.Pin(MISO_PIN))

# Initialize SD card
sd = SDCard(spi, machine.Pin(CS_PIN))

# Mount filesystem
os.mount(sd, '/sd')

# List files on the SD card
print("Files on SD card:")
print(os.listdir('/sd'))

# Unmount SD card
os.umount('/sd')

VSPI and HSPI Pin Configurations

VSPI Connections

The following table shows the VSPI pin connections for an external Micro SD card reader:

Table 9 VSPI Pin Mappings

Pin	Name	ESP32 GPIO	RP2040 GPIO
D3	SS	5	17
CMD	MOSI	23	19
CLK	SCK	18	18
D0	MISO	19	16

HSPI Connections

Below are the HSPI pin connections for the ESP32 microcontroller:

Table 10 HSPI Pin Mappings

Pin	Name	ESP32 GPIO
D3	SS	13
CMD	MOSI	15
CLK	SCK	14
D0	MISO	2

Caution

Ensure to use the correct SPI pins and avoid conflicts when sharing pins between peripherals.

Arduino IDE Compatibility

The Arduino IDE supports SPI communication and allows interfacing with Micro SD cards. Below is an example of using VSPI in Arduino:

VSPI

#include <SPI.h>
#include <SD.h>

#define CS_PIN 5  // Chip Select pin for VSPI

void setup() {
  Serial.begin(115200);
  if (!SD.begin(CS_PIN)) {
    Serial.println("Initialization failed!");
    return;
  }
  Serial.println("Initialization done.");
  File root = SD.open("/");
  while (true) {
    File entry = root.openNextFile();
    if (!entry) break;
    Serial.println(entry.name());
    entry.close();
  }
}

void loop() {}