SD card read writer

Example code of the Raspberry Pi Pico W connected to a Secure Digital (SD) card reader.

Connections

Description	Colour	Pico W	SD card
Power 3v	Orange	pin36 3V3(OUT)	3.3v
Ground	Black	pin3 GND	GND
SPI	Blue	pin14 GP10 SPI1 SCK	SCK
SPI	Yellow	pin15 GP11 SPI1 TX	MOSI
SPI	Green	pin16 GP12 SPI1 RX	MISO
SPI	White	pin17 GP13 SPI1 CSn	CS

Photo

Sketch

	# Raspberry Pi Pico W - with SD card
	# Copyright (C) 2023 https://www.roboticboat.uk
	# eeffa77d-1496-4d39-bcd8-66ca9011815e
	#
	# This program is free software: you can redistribute it and/or modify
	# it under the terms of the GNU General Public License as published by
	# the Free Software Foundation, either version 3 of the License, or
	# (at your option) any later version.
	#
	# This program is distributed in the hope that it will be useful,
	# but WITHOUT ANY WARRANTY; without even the implied warranty of
	# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	# GNU General Public License for more details.
	#
	# You should have received a copy of the GNU General Public License
	# along with this program. If not, see <https://www.gnu.org/licenses/>.
	# These Terms shall be governed and construed in accordance with the laws of
	# England and Wales, without regard to its conflict of law provisions.
	#
	# User Interface https://thonny.org/
	#
	# The sdcard library source is here
	# https://github.com/micropython/micropython-lib/blob/master/micropython/drivers/storage/sdcard/sdcard.py
	# The sdcard.py needs to be also copied to the Pico W, so it can find it

	import machine
	import time
	import uos
	import sdcard

	# Constants
	SPI_SCK_PIN = const(10)
	SPI_MOSI_PIN = const(11)
	SPI_MISO_PIN = const(12)
	SPI_CS_PIN = const(13)

	# Update the User
	print("Testing the SD card")

	# Intialize the SPI network
	spi = machine.SPI(1,baudrate=1000000, polarity=0, phase=0, bits=8,
	firstbit=machine.SPI.MSB,
	sck=machine.Pin(SPI_SCK_PIN),
	mosi=machine.Pin(SPI_MOSI_PIN),
	miso=machine.Pin(SPI_MISO_PIN))

	# SPI chip select pin
	chipSelectPin = machine.Pin(SPI_CS_PIN, machine.Pin.OUT)

	# Initialize SD card object
	sdobj = sdcard.SDCard(spi, chipSelectPin)

	# Create a filesystem object that uses the FAT filesystem format
	fsobj = uos.VfsFat(sdobj)

	# Mount the filesystem object fsobj at the location
	# in the VFS given by the mount_point string
	uos.mount(fsobj, "/")

	# List the top directory contents of the SD card
	directoryList = uos.listdir("/")

	# Update the User
	print(directoryList)

	# Create the output file (so we know it exists)
	file = open("testfile.txt", 'w')

	# Write to the file
	file.write("First line of output file\r\n")

	# Close the file
	file.close()

	# CTRL + C to stop the program running.
	# Without the try: except it is very hard to stop the infinite loop
	try:

	# Infinite loop, like on the Arduino
	while (True):

	# Open a file for appending to the end of the file
	# The file must already exist
	file = open("testfile.txt", 'a')

	# Append to the file
	file.write("abcdefghijklmnopqrstuvwxyz1234567890\r\n")

	# Close the file
	file.close()

	# Sleep for 1 second
	time.sleep(1)

	# Open file for reading (default)
	file = open("testfile.txt", 'r')

	# Read the whole file
	data = file.read()

	# Close the file
	file.close()

	# Update the User
	print(data)

	# Sleep for 1 second
	time.sleep(1)


	# Interrupt handing
	# Capture the CTRL + C event
	except (KeyboardInterrupt, SystemExit):

	# Unmount the filesystem
	uos.umount("/")

	# Update the user
	print ("Well done. Finished\n");

view raw picoW_SDcard.py hosted with ❤ by GitHub