nrf: add micro:bit board

src/machine/board_microbit.go

@@ -0,0 +1,32 @@
+// +build nrf,microbit
+
+package machine
+
+// The micro:bit does not have a 32kHz crystal on board.
+const HasLowFrequencyCrystal = false
+
+// Buttons on the micro:bit (A and B)
+const (
+	BUTTON  = BUTTON1
+	BUTTON1 = 5
+	BUTTON2 = 11
+)
+
+// UART pins
+const (
+	UART_TX_PIN = 24
+	UART_RX_PIN = 25
+)
+
+// ADC pins
+const (
+	ADC0 = 0
+	ADC1 = 1
+	ADC2 = 2
+)
+
+// I2C pins
+const (
+	SDA_PIN = 20
+	SCL_PIN = 19
+)

src/machine/board_pca10040.go

@@ -2,6 +2,9 @@
 
 package machine
 
+// The PCA10040 has a low-frequency (32kHz) crystal oscillator on board.
+const HasLowFrequencyCrystal = true
+
 // LEDs on the PCA10040 (nRF52832 dev board)
 const (
 	LED  = LED1

src/machine/machine_nrf.go

@@ -19,22 +19,25 @@ const (
 // Configure this pin with the given configuration.
 func (p GPIO) Configure(config GPIOConfig) {
 	cfg := config.Mode | nrf.GPIO_PIN_CNF_DRIVE_S0S1 | nrf.GPIO_PIN_CNF_SENSE_Disabled
-	nrf.P0.PIN_CNF[p.Pin] = nrf.RegValue(cfg)
+	port, pin := p.getPortPin()
+	port.PIN_CNF[pin] = nrf.RegValue(cfg)
 }
 
 // Set the pin to high or low.
 // Warning: only use this on an output pin!
 func (p GPIO) Set(high bool) {
+	port, pin := p.getPortPin()
 	if high {
-		nrf.P0.OUTSET = 1 << p.Pin
+		port.OUTSET = 1 << pin
 	} else {
-		nrf.P0.OUTCLR = 1 << p.Pin
+		port.OUTCLR = 1 << pin
 	}
 }
 
 // Get returns the current value of a GPIO pin.
 func (p GPIO) Get() bool {
-	return (nrf.P0.IN>>p.Pin)&1 != 0
+	port, pin := p.getPortPin()
+	return (port.IN>>pin)&1 != 0
 }
 
 // UART
@@ -62,7 +65,7 @@ func (uart UART) Configure(config UARTConfig) {
 	nrf.UART0.INTENSET = nrf.UART_INTENSET_RXDRDY_Msk
 
 	// Enable RX IRQ.
-	arm.EnableIRQ(nrf.IRQ_UARTE0_UART0)
+	arm.EnableIRQ(nrf.IRQ_UART0)
 }
 
 // SetBaudRate sets the communication speed for the UART.
@@ -89,8 +92,7 @@ func (uart UART) WriteByte(c byte) error {
 	return nil
 }
 
-//go:export UARTE0_UART0_IRQHandler
-func handleUART0() {
+func (uart UART) handleInterrupt() {
 	if nrf.UART0.EVENTS_RXDRDY != 0 {
 		bufferPut(byte(nrf.UART0.RXD))
 		nrf.UART0.EVENTS_RXDRDY = 0x0
@@ -128,13 +130,15 @@ func (i2c I2C) Configure(config I2CConfig) {
 	}
 
 	// do config
-	nrf.P0.PIN_CNF[config.SCL] = (nrf.GPIO_PIN_CNF_DIR_Input << nrf.GPIO_PIN_CNF_DIR_Pos) |
+	sclPort, sclPin := GPIO{config.SCL}.getPortPin()
+	sclPort.PIN_CNF[sclPin] = (nrf.GPIO_PIN_CNF_DIR_Input << nrf.GPIO_PIN_CNF_DIR_Pos) |
 		(nrf.GPIO_PIN_CNF_INPUT_Connect << nrf.GPIO_PIN_CNF_INPUT_Pos) |
 		(nrf.GPIO_PIN_CNF_PULL_Pullup << nrf.GPIO_PIN_CNF_PULL_Pos) |
 		(nrf.GPIO_PIN_CNF_DRIVE_S0D1 << nrf.GPIO_PIN_CNF_DRIVE_Pos) |
 		(nrf.GPIO_PIN_CNF_SENSE_Disabled << nrf.GPIO_PIN_CNF_SENSE_Pos)
 
-	nrf.P0.PIN_CNF[config.SDA] = (nrf.GPIO_PIN_CNF_DIR_Input << nrf.GPIO_PIN_CNF_DIR_Pos) |
+	sdaPort, sdaPin := GPIO{config.SDA}.getPortPin()
+	sdaPort.PIN_CNF[sdaPin] = (nrf.GPIO_PIN_CNF_DIR_Input << nrf.GPIO_PIN_CNF_DIR_Pos) |
 		(nrf.GPIO_PIN_CNF_INPUT_Connect << nrf.GPIO_PIN_CNF_INPUT_Pos) |
 		(nrf.GPIO_PIN_CNF_PULL_Pullup << nrf.GPIO_PIN_CNF_PULL_Pos) |
 		(nrf.GPIO_PIN_CNF_DRIVE_S0D1 << nrf.GPIO_PIN_CNF_DRIVE_Pos) |

src/machine/machine_nrf51.go

@@ -0,0 +1,17 @@
+// +build nrf51
+
+package machine
+
+import (
+	"device/nrf"
+)
+
+// Get peripheral and pin number for this GPIO pin.
+func (p GPIO) getPortPin() (*nrf.GPIO_Type, uint8) {
+	return nrf.GPIO, p.Pin
+}
+
+//go:export UART0_IRQHandler
+func handleUART0() {
+	UART0.handleInterrupt()
+}

src/machine/machine_nrf52.go

@@ -7,6 +7,16 @@ import (
 	"unsafe"
 )
 
+// Get peripheral and pin number for this GPIO pin.
+func (p GPIO) getPortPin() (*nrf.GPIO_Type, uint8) {
+	return nrf.P0, p.Pin
+}
+
+//go:export UARTE0_UART0_IRQHandler
+func handleUART0() {
+	UART0.handleInterrupt()
+}
+
 // InitADC initializes the registers needed for ADC.
 func InitADC() {
 	return // no specific setup on nrf52 machine.

src/runtime/runtime_nrf.go

@@ -28,7 +28,9 @@ func init() {
 }
 
 func initLFCLK() {
-	nrf.CLOCK.LFCLKSRC = nrf.CLOCK_LFCLKSTAT_SRC_Xtal
+	if machine.HasLowFrequencyCrystal {
+		nrf.CLOCK.LFCLKSRC = nrf.CLOCK_LFCLKSTAT_SRC_Xtal
+	}
 	nrf.CLOCK.TASKS_LFCLKSTART = 1
 	for nrf.CLOCK.EVENTS_LFCLKSTARTED == 0 {
 	}