mirror of
https://github.com/tinygo-org/tinygo.git
synced 2026-08-04 11:07:46 +00:00
Ayke van Laethem
106 lines
2.2 KiB
Go
106 lines
2.2 KiB
Go
// +build nrf
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package runtime
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import (
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"device/arm"
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"device/nrf"
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"machine"
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)
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type timeUnit int64
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const tickMicros = 1024 * 32
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//go:linkname systemInit SystemInit
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func systemInit()
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//go:export Reset_Handler
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func main() {
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systemInit()
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preinit()
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initAll()
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mainWrapper()
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abort()
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}
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func init() {
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machine.UART0.Configure(machine.UARTConfig{})
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initLFCLK()
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initRTC()
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}
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func initLFCLK() {
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if machine.HasLowFrequencyCrystal {
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nrf.CLOCK.LFCLKSRC = nrf.CLOCK_LFCLKSTAT_SRC_Xtal
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}
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nrf.CLOCK.TASKS_LFCLKSTART = 1
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for nrf.CLOCK.EVENTS_LFCLKSTARTED == 0 {
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}
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nrf.CLOCK.EVENTS_LFCLKSTARTED = 0
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}
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func initRTC() {
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nrf.RTC1.TASKS_START = 1
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// TODO: set priority
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arm.EnableIRQ(nrf.IRQ_RTC1)
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}
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func putchar(c byte) {
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machine.UART0.WriteByte(c)
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}
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func sleepTicks(d timeUnit) {
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for d != 0 {
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ticks() // update timestamp
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ticks := uint32(d) & 0x7fffff // 23 bits (to be on the safe side)
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rtc_sleep(ticks) // TODO: not accurate (must be d / 30.5175...)
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d -= timeUnit(ticks)
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}
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}
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var (
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timestamp timeUnit // nanoseconds since boottime
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rtcLastCounter uint32 // 24 bits ticks
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)
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// Monotonically increasing numer of ticks since start.
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//
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// Note: very long pauses between measurements (more than 8 minutes) may
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// overflow the counter, leading to incorrect results. This might be fixed by
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// handling the overflow event.
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func ticks() timeUnit {
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rtcCounter := uint32(nrf.RTC1.COUNTER)
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offset := (rtcCounter - rtcLastCounter) & 0xffffff // change since last measurement
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rtcLastCounter = rtcCounter
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timestamp += timeUnit(offset) // TODO: not precise
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return timestamp
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}
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//go:volatile
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type isrFlag bool
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var rtc_wakeup isrFlag
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func rtc_sleep(ticks uint32) {
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nrf.RTC1.INTENSET = nrf.RTC_INTENSET_COMPARE0
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rtc_wakeup = false
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if ticks == 1 {
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// Race condition (even in hardware) at ticks == 1.
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// TODO: fix this in a better way by detecting it, like the manual
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// describes.
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ticks = 2
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}
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nrf.RTC1.CC[0] = (nrf.RTC1.COUNTER + nrf.RegValue(ticks)) & 0x00ffffff
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for !rtc_wakeup {
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arm.Asm("wfi")
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}
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}
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//go:export RTC1_IRQHandler
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func handleRTC1() {
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nrf.RTC1.INTENCLR = nrf.RTC_INTENSET_COMPARE0
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nrf.RTC1.EVENTS_COMPARE[0] = 0
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rtc_wakeup = true
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}
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