Seeed XIAO support

Makefile

@@ -296,6 +296,7 @@ smoketest:
 	$(TINYGO) build -size short -o test.hex -target=wioterminal         examples/blinky1
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=pygamer             examples/blinky1
+	$(TINYGO) build -size short -o test.hex -target=xiao                examples/blinky1
 	@$(MD5SUM) test.hex
 ifneq ($(AVR), 0)
 	$(TINYGO) build -size short -o test.hex -target=atmega1284p         examples/serial

README.md

@@ -43,7 +43,7 @@ See the [getting started instructions](https://tinygo.org/getting-started/) for
 
 You can compile TinyGo programs for microcontrollers, WebAssembly and Linux.
 
-The following 33 microcontroller boards are currently supported:
+The following 34 microcontroller boards are currently supported:
 
 * [Adafruit Circuit Playground Bluefruit](https://www.adafruit.com/product/4333)
 * [Adafruit Circuit Playground Express](https://www.adafruit.com/product/3333)
@@ -73,6 +73,7 @@ The following 33 microcontroller boards are currently supported:
 * [Phytec reel board](https://www.phytec.eu/product-eu/internet-of-things/reelboard/)
 * [PineTime DevKit](https://www.pine64.org/pinetime/)
 * [Seeed Wio Terminal](https://www.seeedstudio.com/Wio-Terminal-p-4509.html)
+* [Seeed Seeeduino XIAO](https://www.seeedstudio.com/Seeeduino-XIAO-Arduino-Microcontroller-SAMD21-Cortex-M0+-p-4426.html)
 * [SiFIve HiFive1](https://www.sifive.com/boards/hifive1)
 * [ST Micro "Nucleo F103RB"](https://www.st.com/en/evaluation-tools/nucleo-f103rb.html)
 * [ST Micro STM32F103XX "Bluepill"](http://wiki.stm32duino.com/index.php?title=Blue_Pill)

src/machine/board_xiao.go

@@ -0,0 +1,126 @@
+// +build sam,atsamd21,xiao
+
+package machine
+
+import (
+	"device/sam"
+	"runtime/interrupt"
+)
+
+// used to reset into bootloader
+const RESET_MAGIC_VALUE = 0xf01669ef
+
+// GPIO Pins
+const (
+	D0  = PA02 // can be used for PWM or DAC
+	D1  = PA04 // PWM available
+	D2  = PA10 // PWM available
+	D3  = PA11 // PWM available
+	D4  = PA08 // can be used for PWM or I2C SDA
+	D5  = PA09 // can be used for PWM or I2C SCL
+	D6  = PB08 // can be used for PWM or UART1 TX
+	D7  = PB09 // can be used for PWM or UART1 RX
+	D8  = PA07 // can be used for PWM or SPI SCK
+	D9  = PA05 // can be used for PWM or SPI MISO
+	D10 = PA06 // can be used for PWM or SPI MOSI
+)
+
+// Analog pins
+const (
+	A0  = PA02 // ADC/AIN[0]
+	A1  = PA04 // ADC/AIN[4]
+	A2  = PA10 // ADC/AIN[18]
+	A3  = PA11 // ADC/AIN[19]
+	A4  = PA08 // ADC/AIN[16]
+	A5  = PA09 // ADC/AIN[17]
+	A6  = PB08 // ADC/AIN[2]
+	A7  = PB09 // ADC/AIN[3]
+	A8  = PA07 // ADC/AIN[7]
+	A9  = PA05 // ADC/AIN[6]
+	A10 = PA06 // ADC/AIN[5]
+)
+
+const (
+	LED     = PA17
+	LED_RXL = PA18
+	LED_TXL = PA19
+	LED2    = LED_RXL
+	LED3    = LED_TXL
+)
+
+// UART0 aka USBCDC pins
+const (
+	USBCDC_DM_PIN = PA24
+	USBCDC_DP_PIN = PA25
+)
+
+// UART1 pins
+const (
+	UART_TX_PIN = D6
+	UART_RX_PIN = D7
+)
+
+// UART1 on the Xiao
+var (
+	UART1 = UART{
+		Buffer: NewRingBuffer(),
+		Bus:    sam.SERCOM4_USART,
+		SERCOM: 4,
+	}
+)
+
+func init() {
+	UART1.Interrupt = interrupt.New(sam.IRQ_SERCOM4, UART1.handleInterrupt)
+}
+
+// I2C pins
+const (
+	SDA_PIN = PA08 // SDA: SERCOM2/PAD[0]
+	SCL_PIN = PA09 // SCL: SERCOM2/PAD[1]
+)
+
+// I2C on the Xiao
+var (
+	I2C0 = I2C{
+		Bus:    sam.SERCOM2_I2CM,
+		SERCOM: 2,
+	}
+)
+
+// SPI pins
+const (
+	SPI0_SCK_PIN  = PA07 // SCK: SERCOM0/PAD[3]
+	SPI0_MOSI_PIN = PA06 // MOSI: SERCOM0/PAD[2]
+	SPI0_MISO_PIN = PA05 // MISO: SERCOM0/PAD[1]
+)
+
+// SPI on the Xiao
+var (
+	SPI0 = SPI{
+		Bus:    sam.SERCOM0_SPI,
+		SERCOM: 0,
+	}
+)
+
+// I2S pins
+const (
+	I2S_SCK_PIN = PA10
+	I2S_SD_PIN  = PA08
+	I2S_WS_PIN  = NoPin // TODO: figure out what this is on Xiao
+)
+
+// I2S on the Xiao
+var (
+	I2S0 = I2S{Bus: sam.I2S}
+)
+
+// USB CDC identifiers
+const (
+	usb_STRING_PRODUCT      = "Seeed XIAO M0"
+	usb_STRING_MANUFACTURER = "Seeed"
+)
+
+var (
+	usb_VID uint16 = 0x2886
+	usb_PID uint16 = 0x802F
+)

targets/xiao.json

@@ -0,0 +1,8 @@
+{
+    "inherits": ["atsamd21g18a"],
+    "build-tags": ["sam", "atsamd21g18a", "xiao"],
+    "flash-1200-bps-reset": "true",
+    "flash-method": "msd",
+    "msd-volume-name": "Arduino",
+    "msd-firmware-name": "firmware.uf2"
+}