avr: use standard pin numbering

This commit changes pin numbering for atmega328 based boards (Uno, Nano)
to use the standard format, where pin number is determined by the
pin/port. Previously, pin numbers were based on what the Uno uses, which
does not seem to have a clear pattern.

One difference is that counting starts at port B, as there is no port A.
So PB0 is 0, PB1 is 1… PC0 is 8.

This commit also moves PWM code to the atmega328 file, as it may not be
generic to all ATmega chips.

Author: aykevl

Makefile

@@ -182,7 +182,7 @@ tinygo-test:
 .PHONY: smoketest
 smoketest:
 	$(TINYGO) version
-	# test all examples
+	# test all examples (except pwm)
 	$(TINYGO) build -size short -o test.hex -target=pca10040            examples/blinky1
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=pca10040            examples/adc
@@ -203,8 +203,6 @@ smoketest:
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=microbit            examples/microbit-blink
 	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=pca10040            examples/pwm
-	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=pca10040            examples/serial
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=pca10040            examples/systick
@@ -296,6 +294,8 @@ ifneq ($(AVR), 0)
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=arduino             examples/blinky1
 	@$(MD5SUM) test.hex
+	$(TINYGO) build -size short -o test.hex -target=arduino             examples/pwm
+	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=arduino -scheduler=tasks  examples/blinky1
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=arduino-nano        examples/blinky1

src/examples/button/button.go

@@ -5,11 +5,9 @@ import (
 	"time"
 )
 
-// This example assumes that the button is connected to pin 8. Change the value
-// below to use a different pin.
 const (
 	led    = machine.LED
-	button = machine.Pin(8)
+	button = machine.BUTTON
 )
 
 func main() {

src/examples/pwm/pwm.go

@@ -8,9 +8,9 @@ import (
 // This example assumes that an RGB LED is connected to pins 3, 5 and 6 on an Arduino.
 // Change the values below to use different pins.
 const (
-	redPin   = 3
-	greenPin = 5
-	bluePin  = 6
+	redPin   = machine.D3
+	greenPin = machine.D5
+	bluePin  = machine.D6
 )
 
 // cycleColor is just a placeholder until math/rand or some equivalent is working.

src/machine/board_arduino.go

@@ -7,21 +7,39 @@ func CPUFrequency() uint32 {
 	return 16000000
 }
 
+// Digital pins, marked as plain numbers on the board.
+const (
+	D0  = PD0 // RX
+	D1  = PD1 // TX
+	D2  = PD2
+	D3  = PD3
+	D4  = PD4
+	D5  = PD5
+	D6  = PD6
+	D7  = PD7
+	D8  = PB0
+	D9  = PB1
+	D10 = PB2
+	D11 = PB3
+	D12 = PB4
+	D13 = PB5
+)
+
 // LED on the Arduino
-const LED Pin = 13
+const LED Pin = D13
 
 // ADC on the Arduino
 const (
-	ADC0 Pin = 0
-	ADC1 Pin = 1
-	ADC2 Pin = 2
-	ADC3 Pin = 3
-	ADC4 Pin = 4 // Used by TWI for SDA
-	ADC5 Pin = 5 // Used by TWI for SCL
+	ADC0 Pin = PC0
+	ADC1 Pin = PC1
+	ADC2 Pin = PC2
+	ADC3 Pin = PC3
+	ADC4 Pin = PC4 // Used by TWI for SDA
+	ADC5 Pin = PC5 // Used by TWI for SCL
 )
 
 // UART pins
 const (
-	UART_TX_PIN Pin = 1
-	UART_RX_PIN Pin = 0
+	UART_TX_PIN Pin = PD1
+	UART_RX_PIN Pin = PD0
 )

src/machine/board_arduino_nano.go

@@ -7,21 +7,39 @@ func CPUFrequency() uint32 {
 	return 16000000
 }
 
+// Digital pins.
+const (
+	D0  = PD0 // RX0
+	D1  = PD1 // TX1
+	D2  = PD2
+	D3  = PD3
+	D4  = PD4
+	D5  = PD5
+	D6  = PD6
+	D7  = PD7
+	D8  = PB0
+	D9  = PB1
+	D10 = PB2
+	D11 = PB3
+	D12 = PB4
+	D13 = PB5
+)
+
 // LED on the Arduino
-const LED Pin = 13
+const LED Pin = D13
 
 // ADC on the Arduino
 const (
-	ADC0 Pin = 0
-	ADC1 Pin = 1
-	ADC2 Pin = 2
-	ADC3 Pin = 3
-	ADC4 Pin = 4 // Used by TWI for SDA
-	ADC5 Pin = 5 // Used by TWI for SCL
+	ADC0 Pin = PC0
+	ADC1 Pin = PC1
+	ADC2 Pin = PC2
+	ADC3 Pin = PC3
+	ADC4 Pin = PC4 // Used by TWI for SDA
+	ADC5 Pin = PC5 // Used by TWI for SCL
 )
 
 // UART pins
 const (
-	UART_TX_PIN Pin = 1
-	UART_RX_PIN Pin = 0
+	UART_TX_PIN Pin = PD1
+	UART_RX_PIN Pin = PD0
 )

src/machine/board_atmega328p.go

@@ -0,0 +1,37 @@
+// +build avr,atmega328p arduino arduino_nano
+
+package machine
+
+const (
+	// Note: start at port B because there is no port A.
+	portB Pin = iota * 8
+	portC
+	portD
+)
+
+const (
+	PB0 = portB + 0
+	PB1 = portB + 1
+	PB2 = portB + 2
+	PB3 = portB + 3
+	PB4 = portB + 4
+	PB5 = portB + 5
+	PB6 = portB + 6
+	PB7 = portB + 7
+	PC0 = portC + 0
+	PC1 = portC + 1
+	PC2 = portC + 2
+	PC3 = portC + 3
+	PC4 = portC + 4
+	PC5 = portC + 5
+	PC6 = portC + 6
+	PC7 = portC + 7
+	PD0 = portD + 0
+	PD1 = portD + 1
+	PD2 = portD + 2
+	PD3 = portD + 3
+	PD4 = portD + 4
+	PD5 = portD + 5
+	PD6 = portD + 6
+	PD7 = portD + 7
+)

src/machine/machine_atmega.go

@@ -7,72 +7,6 @@ import (
 	"runtime/interrupt"
 )
 
-// InitPWM initializes the registers needed for PWM.
-func InitPWM() {
-	// use waveform generation
-	avr.TCCR0A.SetBits(avr.TCCR0A_WGM00)
-
-	// set timer 0 prescale factor to 64
-	avr.TCCR0B.SetBits(avr.TCCR0B_CS01 | avr.TCCR0B_CS00)
-
-	// set timer 1 prescale factor to 64
-	avr.TCCR1B.SetBits(avr.TCCR1B_CS11)
-
-	// put timer 1 in 8-bit phase correct pwm mode
-	avr.TCCR1A.SetBits(avr.TCCR1A_WGM10)
-
-	// set timer 2 prescale factor to 64
-	avr.TCCR2B.SetBits(avr.TCCR2B_CS22)
-
-	// configure timer 2 for phase correct pwm (8-bit)
-	avr.TCCR2A.SetBits(avr.TCCR2A_WGM20)
-}
-
-// Configure configures a PWM pin for output.
-func (pwm PWM) Configure() {
-	if pwm.Pin < 8 {
-		avr.DDRD.SetBits(1 << uint8(pwm.Pin))
-	} else {
-		avr.DDRB.SetBits(1 << uint8(pwm.Pin-8))
-	}
-}
-
-// Set turns on the duty cycle for a PWM pin using the provided value. On the AVR this is normally a
-// 8-bit value ranging from 0 to 255.
-func (pwm PWM) Set(value uint16) {
-	value8 := uint8(value >> 8)
-	switch pwm.Pin {
-	case 3:
-		// connect pwm to pin on timer 2, channel B
-		avr.TCCR2A.SetBits(avr.TCCR2A_COM2B1)
-		avr.OCR2B.Set(value8) // set pwm duty
-	case 5:
-		// connect pwm to pin on timer 0, channel B
-		avr.TCCR0A.SetBits(avr.TCCR0A_COM0B1)
-		avr.OCR0B.Set(value8) // set pwm duty
-	case 6:
-		// connect pwm to pin on timer 0, channel A
-		avr.TCCR0A.SetBits(avr.TCCR0A_COM0A1)
-		avr.OCR0A.Set(value8) // set pwm duty
-	case 9:
-		// connect pwm to pin on timer 1, channel A
-		avr.TCCR1A.SetBits(avr.TCCR1A_COM1A1)
-		// this is a 16-bit value, but we only currently allow the low order bits to be set
-		avr.OCR1AL.Set(value8) // set pwm duty
-	case 10:
-		// connect pwm to pin on timer 1, channel B
-		avr.TCCR1A.SetBits(avr.TCCR1A_COM1B1)
-		// this is a 16-bit value, but we only currently allow the low order bits to be set
-		avr.OCR1BL.Set(value8) // set pwm duty
-	case 11:
-		// connect pwm to pin on timer 2, channel A
-		avr.TCCR2A.SetBits(avr.TCCR2A_COM2A1)
-		avr.OCR2A.Set(value8) // set pwm duty
-	default:
-		panic("Invalid PWM pin")
-	}
-}
-
 // I2CConfig is used to store config info for I2C.
 type I2CConfig struct {
 	Frequency uint32