machine/stm32f103xx: implementation of RTC/TIM based timers
Signed-off-by: Ron Evans <ron@hybridgroup.com>
Этот коммит содержится в:
Ron Evans
Ayke van Laethem
родитель
fb8dcde2f9
коммит
f71e1bcf03
3 изменённых файлов: 158 добавлений и 8 удалений
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@ -12,20 +12,32 @@ const (
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FLASH_ACR_LATENCY_2 = 0x00000004
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// Reset and Clock Control Control Register flag values.
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// System Clock source
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RCC_CFGR_SW_HSI = 0
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RCC_CFGR_SW_HSE = 1
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RCC_CFGR_SW_PLL = 2
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// Flags for when System Clock source is set.
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RCC_CFGR_SWS_HSI = 0x00000000
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RCC_CFGR_SWS_HSE = 0x00000004
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RCC_CFGR_SWS_PLL = 0x00000008
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// Sets PCLK1
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RCC_CFGR_PPRE1_DIV_NONE = 0x00000000
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RCC_CFGR_PPRE1_DIV_2 = 0x00000400
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RCC_CFGR_PPRE1_DIV_4 = 0x00000500
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RCC_CFGR_PPRE1_DIV_8 = 0x00000600
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RCC_CFGR_PPRE1_DIV_16 = 0x00000700
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// Sets PCLK2
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RCC_CFGR_PPRE2_DIV_NONE = 0x00000000
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RCC_CFGR_PPRE2_DIV_2 = 0x00002000
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RCC_CFGR_PPRE2_DIV_4 = 0x00002800
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RCC_CFGR_PPRE2_DIV_8 = 0x00003000
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RCC_CFGR_PPRE2_DIV_16 = 0x00003800
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// Sets PLL multiplier
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RCC_CFGR_PLLMUL_2 = 0x00000000
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RCC_CFGR_PLLMUL_3 = 0x00040000
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RCC_CFGR_PLLMUL_4 = 0x00080000
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@ -41,4 +53,9 @@ const (
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RCC_CFGR_PLLMUL_14 = 0x00300000
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RCC_CFGR_PLLMUL_15 = 0x00340000
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RCC_CFGR_PLLMUL_16 = 0x00380000
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// RTC clock source
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RCC_RTCCLKSource_LSE = 0x00000100
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RCC_RTCCLKSource_LSI = 0x00000200
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RCC_RTCCLKSource_HSE_Div128 = 0x00000300
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)
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@ -137,6 +137,7 @@ func (uart UART) Configure(config UARTConfig) {
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stm32.USART1.CR1 = stm32.USART_CR1_TE | stm32.USART_CR1_RE | stm32.USART_CR1_RXNEIE | stm32.USART_CR1_UE
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// Enable RX IRQ.
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arm.SetPriority(stm32.IRQ_USART1, 0xc0)
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arm.EnableIRQ(stm32.IRQ_USART1)
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}
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@ -8,10 +8,10 @@ import (
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"machine"
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)
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const tickMicros = 1 // TODO
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func init() {
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initCLK()
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initRTC()
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initTIM()
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machine.UART0.Configure(machine.UARTConfig{})
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}
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@ -44,13 +44,145 @@ func initCLK() {
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}
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}
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func sleepTicks(d timeUnit) {
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// TODO: use a real timer here
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for i := 0; i < int(d/535); i++ {
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arm.Asm("")
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const tickMicros = 1000
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var (
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timestamp timeUnit // microseconds since boottime
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timerLastCounter uint64
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)
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//go:volatile
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type isrFlag bool
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var timerWakeup isrFlag
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func initRTC() {
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// Enable the PWR and BKP.
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stm32.RCC.APB1ENR |= stm32.RCC_APB1ENR_PWREN | stm32.RCC_APB1ENR_BKPEN
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// access to backup register
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stm32.PWR.CR |= stm32.PWR_CR_DBP
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// Enable LSE
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stm32.RCC.BDCR |= stm32.RCC_BDCR_LSEON
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// wait until LSE is ready
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for stm32.RCC.BDCR&stm32.RCC_BDCR_LSERDY == 0 {
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}
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// Select LSE
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stm32.RCC.BDCR |= stm32.RCC_RTCCLKSource_LSE
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// set prescaler to "max" per datasheet
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stm32.RTC.PRLH = stm32.RTC_PRLH_PRLH_Msk
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stm32.RTC.PRLL = stm32.RTC_PRLL_PRLL_Msk
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// set count to zero
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stm32.RTC.CNTH = 0x0
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stm32.RTC.CNTL = 0x0
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// Enable RTC
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stm32.RCC.BDCR |= stm32.RCC_BDCR_RTCEN
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// Clear RSF
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stm32.RTC.CRL &^= stm32.RTC_CRL_RSF
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// Wait till flag is set
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for stm32.RTC.CRL&stm32.RTC_CRL_RSF == 0 {
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}
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}
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func ticks() timeUnit {
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return 0 // TODO
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// Enable the TIM3 clock.
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func initTIM() {
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stm32.RCC.APB1ENR |= stm32.RCC_APB1ENR_TIM3EN
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arm.SetPriority(stm32.IRQ_TIM3, 0xc3)
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arm.EnableIRQ(stm32.IRQ_TIM3)
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}
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// sleepTicks should sleep for specific number of microseconds.
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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) // current scaling only supports 100 usec to 6553 msec
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timerSleep(ticks)
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d -= timeUnit(ticks)
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}
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}
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// number of ticks (microseconds) since start.
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func ticks() timeUnit {
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// convert RTC counter from seconds to microseconds
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timerCounter := uint64(stm32.RTC.CNTH<<16|stm32.RTC.CNTL) * 1000 * 1000
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// add the fractional part of current time using DIV registers
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timerCounter += (uint64(stm32.RTC.DIVH<<16|stm32.RTC.DIVL) / 1024 * 32 * 32) * 1000 * 1000
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// change since last measurement
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offset := (timerCounter - timerLastCounter)
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timerLastCounter = timerCounter
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timestamp += timeUnit(offset)
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return timestamp
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}
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// ticks are in microseconds
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func timerSleep(ticks uint32) {
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timerWakeup = false
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// STM32 timer update event period is calculated as follows:
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//
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// Update_event = TIM_CLK/((PSC + 1)*(ARR + 1)*(RCR + 1))
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//
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// Where:
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//
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// TIM_CLK = timer clock input
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// PSC = 16-bit prescaler register
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// ARR = 16/32-bit Autoreload register
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// RCR = 16-bit repetition counter
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//
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// Example:
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//
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// TIM_CLK = 72 MHz
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// Prescaler = 1
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// Auto reload = 65535
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// No repetition counter RCR = 0
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// Update_event = 72*(10^6)/((1 + 1)*(65535 + 1)*(1))
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// Update_event = 549.3 Hz
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//
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// Set the timer prescaler/autoreload timing registers.
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// TODO: support smaller or larger scales (autoscaling) based
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// on the length of sleep time requested.
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// The current scaling only supports a range of 100 usec to 6553 msec.
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// prescale counter down from 72mhz to 10khz aka 0.1 ms frequency.
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stm32.TIM3.PSC = machine.CPU_FREQUENCY/10000 - 1 // 7199
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// set duty aka duration
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stm32.TIM3.ARR = stm32.RegValue(ticks/100) - 1 // convert from microseconds to 0.1 ms
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// Enable the hardware interrupt.
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stm32.TIM3.DIER |= stm32.TIM_DIER_UIE
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// Enable the timer.
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stm32.TIM3.CR1 |= stm32.TIM_CR1_CEN
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// wait till timer wakes up
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for !timerWakeup {
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arm.Asm("wfi")
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}
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}
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//go:export TIM3_IRQHandler
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func handleTIM3() {
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if (stm32.TIM3.SR & stm32.TIM_SR_UIF) > 0 {
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// Disable the timer.
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stm32.TIM3.CR1 &^= stm32.TIM_CR1_CEN
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// clear the update flag
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stm32.TIM3.SR &^= stm32.TIM_SR_UIF
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// timer was triggered
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timerWakeup = true
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}
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}
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