Support for Adafruit Feather M0 Express board

src/machine/board_feather-m0-express.go

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+//go:build sam && atsamd21 && feather_m0_express
+
+package machine
+
+// used to reset into bootloader
+const resetMagicValue = 0xf01669ef
+
+// GPIO Pins
+const (
+	D0  = PA11  // UART0 RX
+	D1  = PA10  // UART0 TX
+	D2  = NoPin // does not seem to exist
+	D3  = NoPin // does not seem to exist
+	D4  = NoPin // does not seem to exist
+	D5  = PA15
+	D6  = PA20
+	D7  = NoPin // does not seem to exist
+	D8  = PA06  // NEOPIXEL
+	D9  = PA07
+	D10 = PA18
+	D11 = PA16
+	D12 = PA19
+	D13 = PA17
+)
+
+// Analog pins
+const (
+	A0 = PA02 // ADC/AIN[0]
+	A1 = PB08 // ADC/AIN[2]
+	A2 = PB09 // ADC/AIN[3]
+	A3 = PA04 // ADC/AIN[4]
+	A4 = PA05 // ADC/AIN[5]
+	A5 = PB02 // ADC/AIN[10]
+)
+
+const (
+	LED      = D13
+	NEOPIXEL = D8
+)
+
+// USBCDC pins
+const (
+	USBCDC_DM_PIN = PA24
+	USBCDC_DP_PIN = PA25
+)
+
+// UART1 pins
+const (
+	UART_TX_PIN = D1
+	UART_RX_PIN = D0
+
+	UART1_TX_PIN = D10
+	UART1_RX_PIN = D12
+)
+
+// UART0 on the Feather M0 Express.
+var UART0 = &sercomUSART0
+var UART1 = &sercomUSART1
+
+// I2C pins
+const (
+	SDA_PIN = PA22 // SDA: SERCOM3/PAD[0]
+	SCL_PIN = PA23 // SCL: SERCOM3/PAD[1]
+)
+
+// I2C on the Feather M0 Express.
+var (
+	I2C0 = sercomI2CM3
+)
+
+// SPI pins
+const (
+	SPI0_SCK_PIN = PB11 // SCK: SERCOM4/PAD[3]
+	SPI0_SDO_PIN = PB10 // SDO: SERCOM4/PAD[2]
+	SPI0_SDI_PIN = PA12 // SDI: SERCOM4/PAD[0]
+)
+
+// SPI on the Feather M0.
+var SPI0 = sercomSPIM4
+
+// I2S pins
+const (
+	I2S_SCK_PIN = PA10
+	I2S_SD_PIN  = PA07
+	I2S_WS_PIN  = NoPin // TODO: figure out what this is on Feather M0 Express.
+)
+
+// USB CDC identifiers
+const (
+	usb_STRING_PRODUCT      = "Adafruit Feather M0 Express"
+	usb_STRING_MANUFACTURER = "Adafruit"
+)
+
+var (
+	usb_VID uint16 = 0x239A
+	usb_PID uint16 = 0x801B
+)
+
+var (
+	DefaultUART = UART0
+)

targets/feather-m0-express.json

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+{
+    "inherits": ["atsamd21g18a"],
+    "build-tags": ["feather_m0_express"],
+    "serial": "usb",
+    "serial-port": ["239a:801b"],
+    "flash-1200-bps-reset": "true",
+    "flash-method": "msd",
+    "msd-volume-name": "FEATHERBOOT",
+    "msd-firmware-name": "firmware.uf2"
+}