M5Stack Cardputer

Tags: chip:esp32 chip:esp32s3 arch:xtensa vendor:espressif

The M5Stack Cardputer is a pocket-sized computer kit built around an M5Stamp S3 module (ESP32-S3FN8, dual Xtensa LX7 @ 240 MHz, 8 MB flash, no PSRAM). It integrates a 56-key keyboard, a 1.14” ST7789 TFT, an NS4168 I2S speaker, an SPM1423 microphone, an IR transmitter, a microSD slot and a Grove port.

Features

ESP32-S3FN8 (dual Xtensa LX7 @ 240 MHz), 8 MB flash, no PSRAM
Wi-Fi 4 (2.4 GHz) and Bluetooth LE (native ESP32-S3 radio)
56-key keyboard (8x7 matrix behind a 74HC138 demultiplexer)
1.14” 240x135 ST7789v2 TFT on SPI2
NS4168 mono I2S Class-D speaker amplifier
SPM1423 PDM microphone
IR transmitter, addressable RGB LED (WS2812)
microSD card slot (SPI) and Grove HY2.0-4P (I2C)
USB Type-C (native USB-Serial-JTAG)

Serial Console

By default the NSH console runs over the USB-Serial-JTAG peripheral exposed on the USB Type-C connector. It enumerates on the host as /dev/ttyACM0 (Linux). No external USB-to-UART bridge is required.

Keyboard

The 56-key keyboard is an 8x7 matrix driven by a 74HC138 3-to-8 demultiplexer: three select lines (GPIO8/9/11) choose one of eight rows and seven column lines (GPIO13/15/3/4/5/6/7) are read back. The esp32s3_kbd.c driver scans the matrix on the low-priority work queue and registers a keyboard device at /dev/kbd0, reporting ASCII key codes with SHIFT/CTRL handling. Enable it with CONFIG_ESP32S3_M5_CARDPUTER_KEYBOARD (the lvglterm configuration turns it on).

Note

The key-position-to-character table follows the M5Cardputer layout; verify it against the printed legends on first bring-up. Applications read /dev/kbd0 for key events (for example the lvglterm example, built with its physical-keyboard input variant, feeds it into an on-screen shell).

Pin Mapping

Peripheral	ESP32-S3 GPIO
Keyboard demux select	8 (A0), 9 (A1), 11 (A2)
Keyboard columns	13, 15, 3, 4, 5, 6, 7
ST7789 SPI2 SCLK/MOSI/CS	36 / 35 / 37
ST7789 DC/RST/backlight	34 / 33 / 38
microSD SPI3 SCK/MISO	40 / 39
microSD SPI3 MOSI/CS	14 / 12
Speaker NS4168 BCK/WS/DOUT	41 / 43 / 42
Microphone SPM1423 DATA/CLK	46 / 43 (CLK shared with speaker WS)
IR transmitter	44
RGB LED (WS2812)	21
Grove I2C SDA/SCL	2 / 1
Battery ADC (1:2 divider)	10
USB D-/D+ (native)	19 / 20
BOOT / user button	0

Configurations

All configurations use the USB-Serial-JTAG console and can be selected with:

./tools/configure.sh esp32s3-m5-cardputer:<config>

nsh

Basic NuttShell over USB-Serial-JTAG. Open the console (/dev/ttyACM0) and interact with the shell:

nsh> help
nsh> ls /dev

sdcard

NSH plus the microSD card on SPI3 (FAT), registered as /dev/mmcsd0. Mount it and access the files:

nsh> mount -t vfat /dev/mmcsd0 /mnt
nsh> ls /mnt
nsh> echo "hello" > /mnt/test.txt

fb

ST7789 display exposed as a framebuffer (/dev/fb0). Run the framebuffer example to draw test patterns on the screen:

nsh> fb

wifi

Wi-Fi station. Associate with an access point and obtain an address over DHCP (replace <ssid>/<passphrase> with your network):

nsh> wapi psk wlan0 <passphrase> 3
nsh> wapi essid wlan0 <ssid> 1
nsh> renew wlan0
nsh> ifconfig
nsh> ping 8.8.8.8

softap

Wi-Fi SoftAP with a DHCP server. The board starts the access point NuttX (WPA2/WPA3-SAE, passphrase nuttx12345) at 10.0.0.1. Start the DHCP server so stations that join get an address:

nsh> ifconfig
nsh> dhcpd wlan0

Then connect a client to the NuttX network; it receives an address in the 10.0.0.0/24 range and can reach the board at 10.0.0.1.

lvgl

Graphics support with LVGL on the ST7789 display. Run the LVGL demo:

nsh> lvgldemo

lvglterm

On-screen NuttShell terminal with LVGL and the physical keyboard. Runs the lvglterm example built with its physical-keyboard input variant: NSH output is rendered in an LVGL text area and the keyboard (/dev/kbd0) feeds the input. Wi-Fi is included, so the on-screen shell can associate with an access point using wapi. Fn + ; / . scroll the output:

nsh> lvglterm