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|
//go:build stm32 && stm32f7x2
package runtime
import (
"device/stm32"
"machine"
)
/*
clock settings
+-------------+--------+
| HSE | 8mhz |
| SYSCLK | 216mhz |
| HCLK | 216mhz |
| APB1(PCLK1) | 27mhz |
| APB2(PCLK2) | 108mhz |
+-------------+--------+
*/
const (
HSE_STARTUP_TIMEOUT = 0x0500
PLL_M = 4
PLL_N = 216
PLL_P = 2
PLL_Q = 2
)
func init() {
initCLK()
machine.InitSerial()
initTickTimer(&machine.TIM3)
}
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() {
// PWR_CLK_ENABLE
stm32.RCC.APB1ENR.SetBits(stm32.RCC_APB1ENR_PWREN)
_ = stm32.RCC.APB1ENR.Get()
// PWR_VOLTAGESCALING_CONFIG
stm32.PWR.CR1.ReplaceBits(0x3<<stm32.PWR_CR1_VOS_Pos, stm32.PWR_CR1_VOS_Msk, 0)
_ = stm32.PWR.CR1.Get()
// Initialize the High-Speed External Oscillator
initOsc()
// Set flash wait states (min 7 latency units) based on clock
if (stm32.FLASH.ACR.Get() & stm32.FLASH_ACR_LATENCY_Msk) < 7 {
stm32.FLASH.ACR.ReplaceBits(7, stm32.FLASH_ACR_LATENCY_Msk, 0)
}
// HCLK (0x1C00 = DIV_16, 0x0 = RCC_SYSCLK_DIV1) - ensure timers remain
// within spec as the SYSCLK source changes.
stm32.RCC.CFGR.ReplaceBits(0x00001C00, stm32.RCC_CFGR_PPRE1_Msk, 0)
stm32.RCC.CFGR.ReplaceBits(0x00001C00<<3, stm32.RCC_CFGR_PPRE2_Msk, 0)
stm32.RCC.CFGR.ReplaceBits(0, stm32.RCC_CFGR_HPRE_Msk, 0)
// Set SYSCLK source and wait
// (2 = PLLCLK, 3 = RCC_CFGR_SW mask, 3 << 3 = RCC_CFGR_SWS mask)
stm32.RCC.CFGR.ReplaceBits(2, 3, 0)
for stm32.RCC.CFGR.Get()&(3<<2) != (2 << 2) {
}
// Set flash wait states (max 7 latency units) based on clock
if (stm32.FLASH.ACR.Get() & stm32.FLASH_ACR_LATENCY_Msk) > 7 {
stm32.FLASH.ACR.ReplaceBits(7, stm32.FLASH_ACR_LATENCY_Msk, 0)
}
// Set APB1 and APB2 clocks (0x1800 = DIV8, 0x1000 = DIV2)
stm32.RCC.CFGR.ReplaceBits(0x1800, stm32.RCC_CFGR_PPRE1_Msk, 0)
stm32.RCC.CFGR.ReplaceBits(0x1000<<3, stm32.RCC_CFGR_PPRE2_Msk, 0)
}
func initOsc() {
// Enable HSE, wait until ready
stm32.RCC.CR.SetBits(stm32.RCC_CR_HSEON)
for !stm32.RCC.CR.HasBits(stm32.RCC_CR_HSERDY) {
}
// Disable the PLL, wait until disabled
stm32.RCC.CR.ClearBits(stm32.RCC_CR_PLLON)
for stm32.RCC.CR.HasBits(stm32.RCC_CR_PLLRDY) {
}
// Configure the PLL
stm32.RCC.PLLCFGR.Set(0x20000000 |
(1 << stm32.RCC_PLLCFGR_PLLSRC_Pos) | // 1 = HSE
PLL_M |
(PLL_N << stm32.RCC_PLLCFGR_PLLN_Pos) |
(((PLL_P >> 1) - 1) << stm32.RCC_PLLCFGR_PLLP_Pos) |
(PLL_Q << stm32.RCC_PLLCFGR_PLLQ_Pos))
// Enable the PLL, wait until ready
stm32.RCC.CR.SetBits(stm32.RCC_CR_PLLON)
for !stm32.RCC.CR.HasBits(stm32.RCC_CR_PLLRDY) {
}
}
|
