TinyGo Teensy 3.6 Test

blinky.go

package main

import (
	"device/nxp"
	"machine"
	"runtime"
	"time"
)

const (
	C2_ENABLE        = nxp.UART_C2_TE | nxp.UART_C2_RE | nxp.UART_C2_RIE | nxp.UART_C2_ILIE
	C2_TX_ACTIVE     = C2_ENABLE | nxp.UART_C2_TIE
	C2_TX_COMPLETING = C2_ENABLE | nxp.UART_C2_TCIE
	C2_TX_INACTIVE   = C2_ENABLE

	IRQ_PRIORITY = 64
)

func BAUD2DIV(baud uint32) uint32 {
	return (((machine.CPUFrequency() * 2) + ((baud) >> 1)) / (baud))
}

func main() {
	// nxp.GPIOC.PDDR.SetBits(1 << 5)
	// nxp.PORTC.PCR5.SetBits(nxp.PORT_PCR5_SRE | nxp.PORT_PCR5_DSE | 1<<nxp.PORT_PCR0_MUX_Pos)
	// nxp.PORTC.PCR5.ClearBits(nxp.PORT_PCR5_ODE)
	machine.LED.Configure(machine.PinConfig{Mode: machine.PinOutput})

	serialBegin(BAUD2DIV(9600))
	serialPutchar('\r')
	serialPutchar('\n')

	p := machine.LED.Fast()

	for {
		serialPutchar('a')
		// nxp.GPIOC.PSOR.Set(1 << 5)
		p.Set()
		runtime.Sleep((time.Second / 4).Microseconds())

		// nxp.GPIOC.PCOR.Set(1 << 5)
		p.Clear()
		runtime.Sleep(time.Second.Microseconds())
	}
}

func serialBegin(divisor uint32) {
	// turn on the clock
	nxp.SIM.SCGC4.Set(nxp.SIM_SCGC4_UART0)

	// configure pin 0
	nxp.PORTB.PCR16.Set(nxp.PORT_PCR0_PE | nxp.PORT_PCR0_PS | nxp.PORT_PCR0_PFE | nxp.PORT_PCR0_MUX(3))

	// configure pin 1
	nxp.PORTB.PCR17.Set(nxp.PORT_PCR0_DSE | nxp.PORT_PCR0_SRE | nxp.PORT_PCR0_MUX(3))

	if divisor < 32 {
		divisor = 32
	}

	nxp.UART0.BDH.Set(uint8((divisor >> 13) & 0x1F))
	nxp.UART0.BDL.Set(uint8((divisor >> 5) & 0xFF))
	nxp.UART0.C4.Set(uint8(divisor & 0x1F))
	nxp.UART0.C1.Set(nxp.UART_C1_ILT)
	nxp.UART0.TWFIFO.Set(2) // tx watermark, causes S1_TDRE to set
	nxp.UART0.RWFIFO.Set(4) // rx watermark, causes S1_RDRF to set
	nxp.UART0.PFIFO.Set(nxp.UART_PFIFO_TXFE | nxp.UART_PFIFO_RXFE)
	nxp.UART0.C2.Set(C2_TX_INACTIVE)

	// arm.SetPriority(nxp.IRQ_UART0_RX_TX, IRQ_PRIORITY)
	// arm.EnableIRQ(nxp.IRQ_UART0_RX_TX)
}

func serialPutchar(c byte) {
	if !nxp.SIM.SCGC4.HasBits(nxp.SIM_SCGC4_UART0) {
		return
	}

	if !nxp.UART0.S1.HasBits(nxp.UART_S1_TDRE) {
		// not ready, discard
		return
	}

	nxp.UART0.D.Set(c)
	nxp.UART0.C2.Set(C2_TX_ACTIVE)
}