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//go:build rp2040
// Implementation based on code located here:
// https://github.com/raspberrypi/pico-sdk/blob/master/src/rp2_common/hardware_rtc/rtc.c
package machine
import (
"device/rp"
"errors"
"runtime/interrupt"
"unsafe"
)
type rtcType rp.RTC_Type
type rtcTime struct {
Year int16
Month int8
Day int8
Dotw int8
Hour int8
Min int8
Sec int8
}
var RTC = (*rtcType)(unsafe.Pointer(rp.RTC))
const (
second = 1
minute = 60 * second
hour = 60 * minute
day = 24 * hour
)
var (
rtcAlarmRepeats bool
rtcCallback func()
rtcEpoch = rtcTime{
Year: 1970, Month: 1, Day: 1, Dotw: 4, Hour: 0, Min: 0, Sec: 0,
}
)
var (
ErrRtcDelayTooSmall = errors.New("RTC interrupt deplay is too small, shall be at least 1 second")
ErrRtcDelayTooLarge = errors.New("RTC interrupt deplay is too large, shall be no more than 1 day")
)
// SetInterrupt configures delayed and optionally recurring interrupt by real time clock.
//
// Delay is specified in whole seconds, allowed range depends on platform.
// Zero delay disables previously configured interrupt, if any.
//
// RP2040 implementation allows delay to be up to 1 day, otherwise a respective error is emitted.
func (rtc *rtcType) SetInterrupt(delay uint32, repeat bool, callback func()) error {
// Verify delay range
if delay > day {
return ErrRtcDelayTooLarge
}
// De-configure delayed interrupt if delay is zero
if delay == 0 {
rtc.disableInterruptMatch()
return nil
}
// Configure delayed interrupt
rtc.setDivider()
rtcAlarmRepeats = repeat
rtcCallback = callback
err := rtc.setTime(rtcEpoch)
if err != nil {
return err
}
rtc.setAlarm(toAlarmTime(delay), callback)
return nil
}
func toAlarmTime(delay uint32) rtcTime {
result := rtcEpoch
remainder := delay + 1 // needed "+1", otherwise alarm fires one second too early
if remainder >= hour {
result.Hour = int8(remainder / hour)
remainder %= hour
}
if remainder >= minute {
result.Min = int8(remainder / minute)
remainder %= minute
}
result.Sec = int8(remainder)
return result
}
func (rtc *rtcType) setDivider() {
// Get clk_rtc freq and make sure it is running
rtcFreq := configuredFreq[clkRTC]
if rtcFreq == 0 {
panic("can not set RTC divider, clock is not running")
}
// Take rtc out of reset now that we know clk_rtc is running
resetBlock(rp.RESETS_RESET_RTC)
unresetBlockWait(rp.RESETS_RESET_RTC)
// Set up the 1 second divider.
// If rtc_freq is 400 then clkdiv_m1 should be 399
rtcFreq -= 1
// Check the freq is not too big to divide
if rtcFreq > rp.RTC_CLKDIV_M1_CLKDIV_M1_Msk {
panic("can not set RTC divider, clock frequency is too big to divide")
}
// Write divide value
rtc.CLKDIV_M1.Set(rtcFreq)
}
// setTime configures RTC with supplied time, initialises and activates it.
func (rtc *rtcType) setTime(t rtcTime) error {
// Disable RTC and wait while it is still running
rtc.CTRL.Set(0)
for rtc.isActive() {
}
rtc.SETUP_0.Set((uint32(t.Year) << rp.RTC_SETUP_0_YEAR_Pos) |
(uint32(t.Month) << rp.RTC_SETUP_0_MONTH_Pos) |
(uint32(t.Day) << rp.RTC_SETUP_0_DAY_Pos))
rtc.SETUP_1.Set((uint32(t.Dotw) << rp.RTC_SETUP_1_DOTW_Pos) |
(uint32(t.Hour) << rp.RTC_SETUP_1_HOUR_Pos) |
(uint32(t.Min) << rp.RTC_SETUP_1_MIN_Pos) |
(uint32(t.Sec) << rp.RTC_SETUP_1_SEC_Pos))
// Load setup values into RTC clock domain
rtc.CTRL.SetBits(rp.RTC_CTRL_LOAD)
// Enable RTC and wait for it to be running
rtc.CTRL.SetBits(rp.RTC_CTRL_RTC_ENABLE)
for !rtc.isActive() {
}
return nil
}
func (rtc *rtcType) isActive() bool {
return rtc.CTRL.HasBits(rp.RTC_CTRL_RTC_ACTIVE)
}
// setAlarm configures alarm in RTC and arms it.
// The callback is executed in the context of an interrupt handler,
// so regular restructions for this sort of code apply: no blocking, no memory allocation, etc.
func (rtc *rtcType) setAlarm(t rtcTime, callback func()) {
rtc.disableInterruptMatch()
// Clear all match enable bits
rtc.IRQ_SETUP_0.ClearBits(rp.RTC_IRQ_SETUP_0_YEAR_ENA | rp.RTC_IRQ_SETUP_0_MONTH_ENA | rp.RTC_IRQ_SETUP_0_DAY_ENA)
rtc.IRQ_SETUP_1.ClearBits(rp.RTC_IRQ_SETUP_1_DOTW_ENA | rp.RTC_IRQ_SETUP_1_HOUR_ENA | rp.RTC_IRQ_SETUP_1_MIN_ENA | rp.RTC_IRQ_SETUP_1_SEC_ENA)
// Only add to setup if it isn't -1 and set the match enable bits for things we care about
if t.Year >= 0 {
rtc.IRQ_SETUP_0.SetBits(uint32(t.Year) << rp.RTC_SETUP_0_YEAR_Pos)
rtc.IRQ_SETUP_0.SetBits(rp.RTC_IRQ_SETUP_0_YEAR_ENA)
}
if t.Month >= 0 {
rtc.IRQ_SETUP_0.SetBits(uint32(t.Month) << rp.RTC_SETUP_0_MONTH_Pos)
rtc.IRQ_SETUP_0.SetBits(rp.RTC_IRQ_SETUP_0_MONTH_ENA)
}
if t.Day >= 0 {
rtc.IRQ_SETUP_0.SetBits(uint32(t.Day) << rp.RTC_SETUP_0_DAY_Pos)
rtc.IRQ_SETUP_0.SetBits(rp.RTC_IRQ_SETUP_0_DAY_ENA)
}
if t.Dotw >= 0 {
rtc.IRQ_SETUP_1.SetBits(uint32(t.Dotw) << rp.RTC_SETUP_1_DOTW_Pos)
rtc.IRQ_SETUP_1.SetBits(rp.RTC_IRQ_SETUP_1_DOTW_ENA)
}
if t.Hour >= 0 {
rtc.IRQ_SETUP_1.SetBits(uint32(t.Hour) << rp.RTC_SETUP_1_HOUR_Pos)
rtc.IRQ_SETUP_1.SetBits(rp.RTC_IRQ_SETUP_1_HOUR_ENA)
}
if t.Min >= 0 {
rtc.IRQ_SETUP_1.SetBits(uint32(t.Min) << rp.RTC_SETUP_1_MIN_Pos)
rtc.IRQ_SETUP_1.SetBits(rp.RTC_IRQ_SETUP_1_MIN_ENA)
}
if t.Sec >= 0 {
rtc.IRQ_SETUP_1.SetBits(uint32(t.Sec) << rp.RTC_SETUP_1_SEC_Pos)
rtc.IRQ_SETUP_1.SetBits(rp.RTC_IRQ_SETUP_1_SEC_ENA)
}
// Enable the IRQ at the proc
interrupt.New(rp.IRQ_RTC_IRQ, rtcHandleInterrupt).Enable()
// Enable the IRQ at the peri
rtc.INTE.Set(rp.RTC_INTE_RTC)
rtc.enableInterruptMatch()
}
func (rtc *rtcType) enableInterruptMatch() {
// Set matching and wait for it to be enabled
rtc.IRQ_SETUP_0.SetBits(rp.RTC_IRQ_SETUP_0_MATCH_ENA)
for !rtc.IRQ_SETUP_0.HasBits(rp.RTC_IRQ_SETUP_0_MATCH_ACTIVE) {
}
}
func (rtc *rtcType) disableInterruptMatch() {
// Disable matching and wait for it to stop being active
rtc.IRQ_SETUP_0.ClearBits(rp.RTC_IRQ_SETUP_0_MATCH_ENA)
for rtc.IRQ_SETUP_0.HasBits(rp.RTC_IRQ_SETUP_0_MATCH_ACTIVE) {
}
}
func rtcHandleInterrupt(itr interrupt.Interrupt) {
// Always disable the alarm to clear the current IRQ.
// Even if it is a repeatable alarm, we don't want it to keep firing.
// If it matches on a second it can keep firing for that second.
RTC.disableInterruptMatch()
// Call user callback function
if rtcCallback != nil {
rtcCallback()
}
if rtcAlarmRepeats {
// If it is a repeatable alarm, reset time and re-enable the alarm.
RTC.setTime(rtcEpoch)
RTC.enableInterruptMatch()
}
}
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