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|
//go:build (sam && atsamd51) || (sam && atsame5x)
package runtime
import (
"device/arm"
"device/sam"
"machine"
"machine/usb/cdc"
"runtime/interrupt"
"runtime/volatile"
)
type timeUnit int64
//export Reset_Handler
func main() {
arm.SCB.CPACR.Set(0) // disable FPU if it is enabled
preinit()
run()
exit(0)
}
func init() {
initClocks()
initRTC()
initSERCOMClocks()
initUSBClock()
initADCClock()
enableCache()
cdc.EnableUSBCDC()
machine.USBDev.Configure(machine.UARTConfig{})
machine.InitSerial()
}
func putchar(c byte) {
machine.Serial.WriteByte(c)
}
func getchar() byte {
for machine.Serial.Buffered() == 0 {
Gosched()
}
v, _ := machine.Serial.ReadByte()
return v
}
func buffered() int {
return machine.Serial.Buffered()
}
func initClocks() {
// set flash wait state
sam.NVMCTRL.CTRLA.SetBits(0 << sam.NVMCTRL_CTRLA_RWS_Pos)
// software reset
sam.GCLK.CTRLA.SetBits(sam.GCLK_CTRLA_SWRST)
for sam.GCLK.SYNCBUSY.HasBits(sam.GCLK_SYNCBUSY_SWRST) {
}
// Set OSCULP32K as source of Generic Clock Generator 3
// GCLK->GENCTRL[GENERIC_CLOCK_GENERATOR_XOSC32K].reg = GCLK_GENCTRL_SRC(GCLK_GENCTRL_SRC_OSCULP32K) | GCLK_GENCTRL_GENEN; //generic clock gen 3
sam.GCLK.GENCTRL[3].Set((sam.GCLK_GENCTRL_SRC_OSCULP32K << sam.GCLK_GENCTRL_SRC_Pos) |
sam.GCLK_GENCTRL_GENEN)
for sam.GCLK.SYNCBUSY.HasBits(sam.GCLK_SYNCBUSY_GENCTRL_GCLK3) {
}
// Set OSCULP32K as source of Generic Clock Generator 0
sam.GCLK.GENCTRL[0].Set((sam.GCLK_GENCTRL_SRC_OSCULP32K << sam.GCLK_GENCTRL_SRC_Pos) |
sam.GCLK_GENCTRL_GENEN)
for sam.GCLK.SYNCBUSY.HasBits(sam.GCLK_SYNCBUSY_GENCTRL_GCLK0) {
}
// Enable DFLL48M clock
sam.OSCCTRL.DFLLCTRLA.Set(0)
sam.OSCCTRL.DFLLMUL.Set((0x1 << sam.OSCCTRL_DFLLMUL_CSTEP_Pos) |
(0x1 << sam.OSCCTRL_DFLLMUL_FSTEP_Pos) |
(0x0 << sam.OSCCTRL_DFLLMUL_MUL_Pos))
for sam.OSCCTRL.DFLLSYNC.HasBits(sam.OSCCTRL_DFLLSYNC_DFLLMUL) {
}
sam.OSCCTRL.DFLLCTRLB.Set(0)
for sam.OSCCTRL.DFLLSYNC.HasBits(sam.OSCCTRL_DFLLSYNC_DFLLCTRLB) {
}
sam.OSCCTRL.DFLLCTRLA.SetBits(sam.OSCCTRL_DFLLCTRLA_ENABLE)
for sam.OSCCTRL.DFLLSYNC.HasBits(sam.OSCCTRL_DFLLSYNC_ENABLE) {
}
sam.OSCCTRL.DFLLVAL.Set(sam.OSCCTRL.DFLLVAL.Get())
for sam.OSCCTRL.DFLLSYNC.HasBits(sam.OSCCTRL_DFLLSYNC_DFLLVAL) {
}
sam.OSCCTRL.DFLLCTRLB.Set(sam.OSCCTRL_DFLLCTRLB_WAITLOCK |
sam.OSCCTRL_DFLLCTRLB_CCDIS |
sam.OSCCTRL_DFLLCTRLB_USBCRM)
for !sam.OSCCTRL.STATUS.HasBits(sam.OSCCTRL_STATUS_DFLLRDY) {
}
// set GCLK7 to run at 2MHz, using DFLL48M as clock source
// GCLK7 = 48MHz / 24 = 2MHz
sam.GCLK.GENCTRL[7].Set((sam.GCLK_GENCTRL_SRC_DFLL << sam.GCLK_GENCTRL_SRC_Pos) |
(24 << sam.GCLK_GENCTRL_DIV_Pos) |
sam.GCLK_GENCTRL_GENEN)
for sam.GCLK.SYNCBUSY.HasBits(sam.GCLK_SYNCBUSY_GENCTRL_GCLK7) {
}
// Set up the PLLs
// Set PLL0 to run at 120MHz, using GCLK7 as clock source
sam.GCLK.PCHCTRL[1].Set(sam.GCLK_PCHCTRL_CHEN |
(sam.GCLK_PCHCTRL_GEN_GCLK7 << sam.GCLK_PCHCTRL_GEN_Pos))
// multiplier = 59 + 1 + (0/32) = 60
// PLL0 = 2MHz * 60 = 120MHz
sam.OSCCTRL.DPLL[0].DPLLRATIO.Set((0x0 << sam.OSCCTRL_DPLL_DPLLRATIO_LDRFRAC_Pos) |
(59 << sam.OSCCTRL_DPLL_DPLLRATIO_LDR_Pos))
for sam.OSCCTRL.DPLL[0].DPLLSYNCBUSY.HasBits(sam.OSCCTRL_DPLL_DPLLSYNCBUSY_DPLLRATIO) {
}
// MUST USE LBYPASS DUE TO BUG IN REV A OF SAMD51, via Adafruit lib.
sam.OSCCTRL.DPLL[0].DPLLCTRLB.Set((sam.OSCCTRL_DPLL_DPLLCTRLB_REFCLK_GCLK << sam.OSCCTRL_DPLL_DPLLCTRLB_REFCLK_Pos) |
sam.OSCCTRL_DPLL_DPLLCTRLB_LBYPASS)
sam.OSCCTRL.DPLL[0].DPLLCTRLA.Set(sam.OSCCTRL_DPLL_DPLLCTRLA_ENABLE)
for !sam.OSCCTRL.DPLL[0].DPLLSTATUS.HasBits(sam.OSCCTRL_DPLL_DPLLSTATUS_CLKRDY) ||
!sam.OSCCTRL.DPLL[0].DPLLSTATUS.HasBits(sam.OSCCTRL_DPLL_DPLLSTATUS_LOCK) {
}
// Set PLL1 to run at 100MHz, using GCLK7 as clock source
sam.GCLK.PCHCTRL[2].Set(sam.GCLK_PCHCTRL_CHEN |
(sam.GCLK_PCHCTRL_GEN_GCLK7 << sam.GCLK_PCHCTRL_GEN_Pos))
// multiplier = 49 + 1 + (0/32) = 50
// PLL1 = 2MHz * 50 = 100MHz
sam.OSCCTRL.DPLL[1].DPLLRATIO.Set((0x0 << sam.OSCCTRL_DPLL_DPLLRATIO_LDRFRAC_Pos) |
(49 << sam.OSCCTRL_DPLL_DPLLRATIO_LDR_Pos))
for sam.OSCCTRL.DPLL[1].DPLLSYNCBUSY.HasBits(sam.OSCCTRL_DPLL_DPLLSYNCBUSY_DPLLRATIO) {
}
// // MUST USE LBYPASS DUE TO BUG IN REV A OF SAMD51
sam.OSCCTRL.DPLL[1].DPLLCTRLB.Set((sam.OSCCTRL_DPLL_DPLLCTRLB_REFCLK_GCLK << sam.OSCCTRL_DPLL_DPLLCTRLB_REFCLK_Pos) |
sam.OSCCTRL_DPLL_DPLLCTRLB_LBYPASS)
sam.OSCCTRL.DPLL[1].DPLLCTRLA.Set(sam.OSCCTRL_DPLL_DPLLCTRLA_ENABLE)
// for !sam.OSCCTRL.DPLLSTATUS1.HasBits(sam.OSCCTRL_DPLLSTATUS_CLKRDY) ||
// !sam.OSCCTRL.DPLLSTATUS1.HasBits(sam.OSCCTRL_DPLLSTATUS_LOCK) {
// }
// Set up the peripheral clocks
// Set 48MHZ CLOCK FOR USB
sam.GCLK.GENCTRL[1].Set((sam.GCLK_GENCTRL_SRC_DFLL << sam.GCLK_GENCTRL_SRC_Pos) |
sam.GCLK_GENCTRL_IDC |
sam.GCLK_GENCTRL_GENEN)
for sam.GCLK.SYNCBUSY.HasBits(sam.GCLK_SYNCBUSY_GENCTRL_GCLK1) {
}
// // Set 100MHZ CLOCK FOR OTHER PERIPHERALS
// sam.GCLK.GENCTRL2.Set((sam.GCLK_GENCTRL_SRC_DPLL1 << sam.GCLK_GENCTRL_SRC_Pos) |
// sam.GCLK_GENCTRL_IDC |
// sam.GCLK_GENCTRL_GENEN)
// for sam.GCLK.SYNCBUSY.HasBits(sam.GCLK_SYNCBUSY_GENCTRL2) {
// }
// // Set 12MHZ CLOCK FOR DAC
sam.GCLK.GENCTRL[4].Set((sam.GCLK_GENCTRL_SRC_DFLL << sam.GCLK_GENCTRL_SRC_Pos) |
sam.GCLK_GENCTRL_IDC |
(4 << sam.GCLK_GENCTRL_DIVSEL_Pos) |
sam.GCLK_GENCTRL_GENEN)
for sam.GCLK.SYNCBUSY.HasBits(sam.GCLK_SYNCBUSY_GENCTRL_GCLK4) {
}
// // Set up main clock
sam.GCLK.GENCTRL[0].Set((sam.GCLK_GENCTRL_SRC_DPLL0 << sam.GCLK_GENCTRL_SRC_Pos) |
sam.GCLK_GENCTRL_IDC |
sam.GCLK_GENCTRL_GENEN)
for sam.GCLK.SYNCBUSY.HasBits(sam.GCLK_SYNCBUSY_GENCTRL_GCLK0) {
}
sam.MCLK.CPUDIV.Set(sam.MCLK_CPUDIV_DIV_DIV1)
// Use the LDO regulator by default
sam.SUPC.VREG.ClearBits(sam.SUPC_VREG_SEL)
// Start up the "Debug Watchpoint and Trace" unit, so that we can use
// it's 32bit cycle counter for timing.
//CoreDebug->DEMCR |= CoreDebug_DEMCR_TRCENA_Msk;
//DWT->CTRL |= DWT_CTRL_CYCCNTENA_Msk;
// Disable automatic NVM write operations
sam.NVMCTRL.SetCTRLA_WMODE(sam.NVMCTRL_CTRLA_WMODE_MAN)
}
func initRTC() {
// turn on digital interface clock
sam.MCLK.APBAMASK.SetBits(sam.MCLK_APBAMASK_RTC_)
// disable RTC
sam.RTC_MODE0.CTRLA.ClearBits(sam.RTC_MODE0_CTRLA_ENABLE)
//sam.RTC_MODE0.CTRLA.Set(0)
for sam.RTC_MODE0.SYNCBUSY.HasBits(sam.RTC_MODE0_SYNCBUSY_ENABLE) {
}
// reset RTC
sam.RTC_MODE0.CTRLA.SetBits(sam.RTC_MODE0_CTRLA_SWRST)
for sam.RTC_MODE0.SYNCBUSY.HasBits(sam.RTC_MODE0_SYNCBUSY_SWRST) {
}
// set to use ulp 32k oscillator
sam.OSC32KCTRL.OSCULP32K.SetBits(sam.OSC32KCTRL_OSCULP32K_EN32K)
sam.OSC32KCTRL.RTCCTRL.Set(sam.OSC32KCTRL_RTCCTRL_RTCSEL_ULP32K)
// set Mode0 to 32-bit counter (mode 0) with prescaler 1 and GCLK2 is 32KHz/1
sam.RTC_MODE0.CTRLA.Set((sam.RTC_MODE0_CTRLA_MODE_COUNT32 << sam.RTC_MODE0_CTRLA_MODE_Pos) |
(sam.RTC_MODE0_CTRLA_PRESCALER_DIV1 << sam.RTC_MODE0_CTRLA_PRESCALER_Pos) |
(sam.RTC_MODE0_CTRLA_COUNTSYNC))
// re-enable RTC
sam.RTC_MODE0.CTRLA.SetBits(sam.RTC_MODE0_CTRLA_ENABLE)
for sam.RTC_MODE0.SYNCBUSY.HasBits(sam.RTC_MODE0_SYNCBUSY_ENABLE) {
}
irq := interrupt.New(sam.IRQ_RTC, func(interrupt.Interrupt) {
flags := sam.RTC_MODE0.INTFLAG.Get()
if flags&sam.RTC_MODE0_INTENSET_CMP0 != 0 {
// The timer (for a sleep) has expired.
timerWakeup.Set(1)
}
if flags&sam.RTC_MODE0_INTENSET_OVF != 0 {
// The 32-bit RTC timer has overflowed.
rtcOverflows.Set(rtcOverflows.Get() + 1)
}
// Mark this interrupt has handled for CMP0 and OVF.
sam.RTC_MODE0.INTFLAG.Set(sam.RTC_MODE0_INTENSET_CMP0 | sam.RTC_MODE0_INTENSET_OVF)
})
sam.RTC_MODE0.INTENSET.Set(sam.RTC_MODE0_INTENSET_OVF)
irq.SetPriority(0xc0)
irq.Enable()
}
func waitForSync() {
for sam.RTC_MODE0.SYNCBUSY.HasBits(sam.RTC_MODE0_SYNCBUSY_COUNT) {
}
}
var rtcOverflows volatile.Register32 // number of times the RTC wrapped around
var timerWakeup volatile.Register8
// ticksToNanoseconds converts RTC ticks (at 32768Hz) to nanoseconds.
func ticksToNanoseconds(ticks timeUnit) int64 {
// The following calculation is actually the following, but with both sides
// reduced to reduce the risk of overflow:
// ticks * 1e9 / 32768
return int64(ticks) * 1953125 / 64
}
// nanosecondsToTicks converts nanoseconds to RTC ticks (running at 32768Hz).
func nanosecondsToTicks(ns int64) timeUnit {
// The following calculation is actually the following, but with both sides
// reduced to reduce the risk of overflow:
// ns * 32768 / 1e9
return timeUnit(ns * 64 / 1953125)
}
// sleepTicks should sleep for d number of microseconds.
func sleepTicks(d timeUnit) {
for d != 0 {
ticks := uint32(d)
if !timerSleep(ticks) {
return
}
d -= timeUnit(ticks)
}
}
// ticks returns the elapsed time since reset.
func ticks() timeUnit {
// For some ways of capturing the time atomically, see this thread:
// https://www.eevblog.com/forum/microcontrollers/correct-timing-by-timer-overflow-count/msg749617/#msg749617
// Here, instead of re-reading the counter register if an overflow has been
// detected, we simply try again because that results in smaller code.
for {
mask := interrupt.Disable()
counter := readRTC()
overflows := rtcOverflows.Get()
hasOverflow := sam.RTC_MODE0.INTFLAG.Get()&sam.RTC_MODE0_INTENSET_OVF != 0
interrupt.Restore(mask)
if hasOverflow {
// There was an overflow while trying to capture the timer.
// Try again.
continue
}
// This is a 32-bit timer, so the number of timer overflows forms the
// upper 32 bits of this timer.
return timeUnit(overflows)<<32 + timeUnit(counter)
}
}
func readRTC() uint32 {
waitForSync()
return sam.RTC_MODE0.COUNT.Get()
}
// ticks are in microseconds
// Returns true if the timer completed.
// Returns false if another interrupt occurred which requires an early return to scheduler.
func timerSleep(ticks uint32) bool {
timerWakeup.Set(0)
if ticks < 8 {
// due to delay waiting for the register value to sync, the minimum sleep value
// for the SAMD51 is 260us.
// For related info for SAMD21, see:
// https://community.atmel.com/comment/2507091#comment-2507091
ticks = 8
}
// request read of count
waitForSync()
// set compare value
cnt := sam.RTC_MODE0.COUNT.Get()
sam.RTC_MODE0.COMP[0].Set(uint32(cnt) + ticks)
// enable IRQ for CMP0 compare
sam.RTC_MODE0.INTENSET.Set(sam.RTC_MODE0_INTENSET_CMP0)
wait:
waitForEvents()
if timerWakeup.Get() != 0 {
return true
}
if hasScheduler {
// The interurpt may have awoken a goroutine, so bail out early.
// Disable IRQ for CMP0 compare.
sam.RTC_MODE0.INTENCLR.Set(sam.RTC_MODE0_INTENSET_CMP0)
return false
} else {
// This is running without a scheduler.
// The application expects this to sleep the whole time.
goto wait
}
}
func initUSBClock() {
// Turn on clock(s) for USB
//MCLK->APBBMASK.reg |= MCLK_APBBMASK_USB;
//MCLK->AHBMASK.reg |= MCLK_AHBMASK_USB;
sam.MCLK.APBBMASK.SetBits(sam.MCLK_APBBMASK_USB_)
sam.MCLK.AHBMASK.SetBits(sam.MCLK_AHBMASK_USB_)
// Put Generic Clock Generator 1 as source for USB
//GCLK->PCHCTRL[USB_GCLK_ID].reg = GCLK_PCHCTRL_GEN_GCLK1_Val | (1 << GCLK_PCHCTRL_CHEN_Pos);
sam.GCLK.PCHCTRL[sam.PCHCTRL_GCLK_USB].Set((sam.GCLK_PCHCTRL_GEN_GCLK1 << sam.GCLK_PCHCTRL_GEN_Pos) |
sam.GCLK_PCHCTRL_CHEN)
}
func initADCClock() {
// Turn on clocks for ADC0/ADC1.
sam.MCLK.APBDMASK.SetBits(sam.MCLK_APBDMASK_ADC0_)
sam.MCLK.APBDMASK.SetBits(sam.MCLK_APBDMASK_ADC1_)
// Put Generic Clock Generator 1 as source for ADC0 and ADC1.
sam.GCLK.PCHCTRL[sam.PCHCTRL_GCLK_ADC0].Set((sam.GCLK_PCHCTRL_GEN_GCLK1 << sam.GCLK_PCHCTRL_GEN_Pos) |
sam.GCLK_PCHCTRL_CHEN)
sam.GCLK.PCHCTRL[sam.PCHCTRL_GCLK_ADC1].Set((sam.GCLK_PCHCTRL_GEN_GCLK1 << sam.GCLK_PCHCTRL_GEN_Pos) |
sam.GCLK_PCHCTRL_CHEN)
}
func enableCache() {
sam.CMCC.CTRL.SetBits(sam.CMCC_CTRL_CEN)
}
func waitForEvents() {
arm.Asm("wfe")
}
|