Seeeduino XIAO
Overview
The Seeeduino XIAO is a tiny (20 mm x 17.5 mm) ARM development board with onboard LEDs, USB port, and range of I/O broken out onto 14 pins.
Hardware
ATSAMD21G18A ARM Cortex-M0+ processor at 48 MHz
256 KiB flash memory and 32 KiB of RAM
Three user LEDs
Native USB port
Supported Features
The seeeduino_xiao board supports the hardware features listed below.
- on-chip / on-board
- Feature integrated in the SoC / present on the board.
- 2 / 2
-
Number of instances that are enabled / disabled.
Click on the label to see the first instance of this feature in the board/SoC DTS files. -
vnd,foo -
Compatible string for the Devicetree binding matching the feature.
Click on the link to view the binding documentation.
seeeduino_xiao/samd21g18a target
Type |
Location |
Description |
Compatible |
|---|---|---|---|
CPU |
on-chip |
ARM Cortex-M0+ CPU1 |
|
ADC |
on-chip |
Atmel SAM0 family ADC1 |
|
ARM architecture |
on-chip |
Atmel SAM0 multi-protocol (UART, SPI, I2C) SERCOM unit3 |
|
on-chip |
For locating the Device ID (serial number) on Atmel SAM0 devices1 |
||
Clock control |
on-chip |
Atmel SAM0 Main Clock Controller (MCLK)1 |
|
on-chip |
Atmel SAMD0 Generic Clock Controller (GCLK)1 |
||
Counter |
on-chip |
Atmel SAM0 basic timer counter (TC) operating in 32-bit wide mode2 |
|
DAC |
on-chip |
Atmel SAM0 family DAC1 |
|
DMA |
on-chip |
Atmel SAM0 DMA controller1 |
|
Flash controller |
on-chip |
Atmel SAM0 NVMC (Non-Volatile Memory Controller)1 |
|
GPIO & Headers |
on-chip |
SAM0 GPIO PORT node2 |
|
on-board |
GPIO pins exposed on Seeeduino Xiao (and compatible devices) headers1 |
||
I2C |
on-chip |
Atmel SAM0 series SERCOM I2C1 |
|
Interrupt controller |
on-chip |
ARMv6-M NVIC (Nested Vectored Interrupt Controller) controller1 |
|
on-chip |
Atmel SAM0 series External Interrupt Controller1 |
||
LED |
on-board |
Group of GPIO-controlled LEDs1 |
|
MTD |
on-chip |
Flash node1 |
|
on-board |
Fixed partitions of a flash (or other non-volatile storage) memory1 |
||
Pin control |
on-chip |
Atmel SAM0 PINMUX2 |
|
on-chip |
Atmel SAM0 Pinctrl Container1 |
||
RTC |
on-chip |
Atmel SAM0 RTC1 |
|
Serial controller |
on-chip |
Atmel SAM0 SERCOM UART driver1 |
|
SPI |
on-chip |
Atmel SAM0 SERCOM SPI controller1 |
|
SRAM |
on-chip |
Generic on-chip SRAM description1 |
|
Timer |
on-chip |
ARMv6-M System Tick1 |
|
USB |
on-chip |
Atmel SAM0 USB in device mode1 |
|
Watchdog |
on-chip |
Atmel SAM0 watchdog1 |
Connections and IOs
The Seeeduino XIAO wiki [1] has detailed information about the board including pinouts [2] and the schematic [3].
System Clock
The SAMD21 MCU is configured to use the 32 kHz external crystal with the on-chip PLL generating the 48 MHz system clock. The internal APB and GCLK unit are set up in the same way as the upstream Arduino libraries.
SPI Port
The SAMD21 MCU has 6 SERCOM based SPIs. On the XIAO, SERCOM0 can be put into SPI mode and used to connect to devices over pin 9 (MISO), pin 10 (MOSI), and pin 8 (SCK).
I2C Port
The SAMD21 MCU has 6 SERCOM based USARTs. On the XIAO, SERCOM2 is available on pin 4 (SDA) and pin 5 (SCL).
Serial Port
The SAMD21 MCU has 6 SERCOM based USARTs. On the XIAO, SERCOM4 is the Zephyr console and is available on pins 7 (RX) and 6 (TX).
USB Device Port
The SAMD21 MCU has a USB device port that can be used to communicate with a host PC. See the USB device support sample applications for more, such as the USB CDC-ACM sample which sets up a virtual serial port that echos characters back to the host PC.
DAC
The SAMD21 MCU has a single channel DAC with 10 bits of resolution. On the XIAO, the DAC is available on pin 0.
Programming and Debugging
The XIAO ships the BOSSA compatible UF2 bootloader. The bootloader can be entered by shorting the RST and GND pads twice.
Additionally, if CONFIG_USB_CDC_ACM is enabled then the bootloader
will be entered automatically when you run west flash.
Flashing
Build the Zephyr kernel and the Hello World sample application:
west build -b seeeduino_xiao samples/hello_world
Connect the XIAO to your host computer using USB
Connect a 3.3 V USB to serial adapter to the board and to the host. See the Serial Port section above for the board’s pin connections.
Run your favorite terminal program to listen for output. Under Linux the terminal should be
/dev/ttyUSB0. For example:$ minicom -D /dev/ttyUSB0 -o
The -o option tells minicom not to send the modem initialization string. Connection should be configured as follows:
Speed: 115200
Data: 8 bits
Parity: None
Stop bits: 1
Short the RST and GND pads twice quickly to enter bootloader mode
Flash the image:
west build -b seeeduino_xiao samples/hello_world west flash
You should see “Hello World! seeeduino_xiao” in your terminal.