Add Feather M0 Board (#356)

* Add Feather M0 Board

.circleci/config.yml

@@ -79,6 +79,7 @@ commands:
       - run: tinygo build -size short -o test.elf -target=pca10056            examples/blinky1
       - run: tinygo build -size short -o test.elf -target=pca10056            examples/blinky2
       - run: tinygo build -size short -o test.elf -target=itsybitsy-m0        examples/blinky1
+      - run: tinygo build -size short -o test.elf -target=feather-m0          examples/blinky1
       - run: tinygo build -size short -o test.elf -target=trinket-m0          examples/blinky1
       - run: tinygo build -size short -o test.elf -target=circuitplay-express examples/blinky1
       - run: tinygo build -size short -o test.elf -target=stm32f4disco        examples/blinky1

src/machine/board_feather-m0.go

@@ -0,0 +1,75 @@
+// +build sam,atsamd21,itsybitsy_m0
+
+package machine
+
+import "device/sam"
+
+// GPIO Pins
+const (
+	D0  = PA11 // UART0 RX
+	D1  = PA10 // UART0 TX
+	D2  = 0xff // does not seem to exist
+	D3  = PA09
+	D4  = PA08
+	D5  = PA15 // PWM available
+	D6  = PA20 // PWM available
+	D7  = 0xff // does not seem to exist
+	D8  = PA06
+	D9  = PA07 // PWM available
+	D10 = PA18 // can be used for PWM or UART1 TX
+	D11 = PA16 // can be used for PWM or UART1 RX
+	D12 = PA19 // PWM available
+	D13 = PA17 // PWM available
+)
+
+// 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
+)
+
+// UART0 aka USBCDC pins
+const (
+	USBCDC_DM_PIN = PA24
+	USBCDC_DP_PIN = PA25
+)
+
+// UART1 pins
+const (
+	UART_TX_PIN = D10
+	UART_RX_PIN = D11
+)
+
+// I2C pins
+const (
+	SDA_PIN = PA22 // SDA: SERCOM3/PAD[0]
+	SCL_PIN = PA23 // SCL: SERCOM3/PAD[1]
+)
+
+// I2C on the Feather M0.
+var (
+	I2C0 = I2C{Bus: sam.SERCOM3_I2CM,
+		SDA:     SDA_PIN,
+		SCL:     SCL_PIN,
+		PinMode: GPIO_SERCOM}
+)
+
+// SPI pins
+const (
+	SPI0_SCK_PIN  = PB11 // SCK: SERCOM4/PAD[3]
+	SPI0_MOSI_PIN = PB10 // MOSI: SERCOM4/PAD[2]
+	SPI0_MISO_PIN = PA12 // MISO: SERCOM4/PAD[0]
+)
+
+// SPI on the Feather M0.
+var (
+	SPI0 = SPI{Bus: sam.SERCOM4_SPI}
+)

targets/feather-m0.json

@@ -0,0 +1,5 @@
+{
+    "inherits": ["atsamd21g18a"],
+    "build-tags": ["sam", "atsamd21g18a", "feather_m0"],
+    "flash": "bossac -d -i -e -w -v -R --offset=0x2000 {hex}"
+}