stm32: initial support

src/machine/machine_dummy.go

@@ -1,4 +1,4 @@
-// +build !avr,!nrf
+// +build !avr,!nrf,!stm32
 
 package machine
 

src/machine/machine_stm32.go

@@ -0,0 +1,81 @@
+// +build stm32
+
+package machine
+
+// Peripheral abstraction layer for the stm32.
+
+import (
+	"device/stm32"
+)
+
+type GPIOMode uint8
+
+const (
+	GPIO_INPUT  = 0 // Input mode
+	GPIO_OUTPUT = 2 // Output mode, max speed 2MHz
+)
+
+const (
+	portA = iota * 16
+	portB
+	portC
+	portD
+	portE
+	portF
+	portG
+)
+
+const (
+	LED = portC + 13
+)
+
+func (p GPIO) getPort() *stm32.GPIO_Type {
+	switch p.Pin / 16 {
+	case 0:
+		return stm32.GPIOA
+	case 1:
+		return stm32.GPIOB
+	case 2:
+		return stm32.GPIOC
+	case 3:
+		return stm32.GPIOD
+	case 4:
+		return stm32.GPIOE
+	case 5:
+		return stm32.GPIOF
+	case 6:
+		return stm32.GPIOG
+	default:
+		panic("machine: unknown port")
+	}
+}
+
+// Configure this pin with the given configuration.
+func (p GPIO) Configure(config GPIOConfig) {
+	// Enable clock.
+	// Do this always, as it isn't known whether the clock has already been
+	// enabled.
+	stm32.RCC.APB2ENR |= stm32.RCC_APB2ENR_IOPCEN_Msk;
+
+	// Configure the GPIO pin.
+	port := p.getPort()
+	pin := p.Pin % 16
+	pos := p.Pin % 8 * 4
+	if pin < 8 {
+		port.CRL = stm32.RegValue((uint32(port.CRL) &^ (0xf << pos)) | (uint32(config.Mode) << pos))
+	} else {
+		port.CRH = stm32.RegValue((uint32(port.CRH) &^ (0xf << pos)) | (uint32(config.Mode) << pos))
+	}
+}
+
+// Set the pin to high or low.
+// Warning: only use this on an output pin!
+func (p GPIO) Set(high bool) {
+	port := p.getPort()
+	pin := p.Pin % 16
+	if high {
+		port.BSRR = 1 << pin
+	} else {
+		port.BSRR = 1 << (pin + 16)
+	}
+}