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//go:build stm32f4 && (stm32f407 || stm32f469)
package runtime
import (
"device/stm32"
"machine"
)
func init() {
initCLK()
machine.InitSerial()
initTickTimer(&machine.TIM2)
}
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 initCLK() {
// Reset clock registers
// Set HSION
stm32.RCC.CR.SetBits(stm32.RCC_CR_HSION)
for !stm32.RCC.CR.HasBits(stm32.RCC_CR_HSIRDY) {
}
// Reset CFGR
stm32.RCC.CFGR.Set(0x00000000)
// Reset HSEON, CSSON and PLLON
stm32.RCC.CR.ClearBits(stm32.RCC_CR_HSEON | stm32.RCC_CR_CSSON | stm32.RCC_CR_PLLON)
// Reset PLLCFGR
stm32.RCC.PLLCFGR.Set(0x24003010)
// Reset HSEBYP
stm32.RCC.CR.ClearBits(stm32.RCC_CR_HSEBYP)
// Disable all interrupts
stm32.RCC.CIR.Set(0x00000000)
// Set up the clock
var startupCounter uint32 = 0
// Enable HSE
stm32.RCC.CR.Set(stm32.RCC_CR_HSEON)
// Wait till HSE is ready and if timeout is reached exit
for {
startupCounter++
if stm32.RCC.CR.HasBits(stm32.RCC_CR_HSERDY) || (startupCounter == HSE_STARTUP_TIMEOUT) {
break
}
}
if stm32.RCC.CR.HasBits(stm32.RCC_CR_HSERDY) {
// Enable high performance mode, configure maximum system frequency.
stm32.RCC.APB1ENR.SetBits(stm32.RCC_APB1ENR_PWREN)
stm32.PWR.CR.SetBits(0x4000) // PWR_CR_VOS
// HCLK = SYSCLK / 1
stm32.RCC.CFGR.SetBits(stm32.RCC_CFGR_HPRE_Div1 << stm32.RCC_CFGR_HPRE_Pos)
// PCLK2 = HCLK / 2
stm32.RCC.CFGR.SetBits(stm32.RCC_CFGR_PPRE2_Div2 << stm32.RCC_CFGR_PPRE2_Pos)
// PCLK1 = HCLK / 4
stm32.RCC.CFGR.SetBits(stm32.RCC_CFGR_PPRE1_Div4 << stm32.RCC_CFGR_PPRE1_Pos)
// Configure the main PLL
stm32.RCC.PLLCFGR.Set(PLL_CFGR)
// Enable main PLL
stm32.RCC.CR.SetBits(stm32.RCC_CR_PLLON)
// Wait till the main PLL is ready
for (stm32.RCC.CR.Get() & stm32.RCC_CR_PLLRDY) == 0 {
}
// Configure Flash prefetch, Instruction cache, Data cache and wait state
stm32.FLASH.ACR.Set(stm32.FLASH_ACR_ICEN | stm32.FLASH_ACR_DCEN | (5 << stm32.FLASH_ACR_LATENCY_Pos))
// Select the main PLL as system clock source
stm32.RCC.CFGR.ClearBits(stm32.RCC_CFGR_SW_Msk)
stm32.RCC.CFGR.SetBits(stm32.RCC_CFGR_SW_PLL << stm32.RCC_CFGR_SW_Pos)
for (stm32.RCC.CFGR.Get() & stm32.RCC_CFGR_SWS_Msk) != (stm32.RCC_CFGR_SWS_PLL << stm32.RCC_CFGR_SWS_Pos) {
}
} else {
// If HSE failed to start up, the application will have wrong clock configuration
for {
}
}
// Enable the CCM RAM clock
stm32.RCC.AHB1ENR.SetBits(1 << 20)
}
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