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stm32/mboot: Use PLL3 for USB clock source on H7 MCUs. 

PLL3-Q is more reliable than PLL1-Q for the USB clock source when entering
mboot from various reset states (eg power on vs MCU reset).  (It was found
that if the main application used PLL3-Q then sometimes the USB clock
source would stay stuck on PLL3-Q and not switch to PLL1-Q after a reset.)

Other related changes:
- SystemCoreClockUpdate() should be called on H7 because the calculation
  can be involved in some cases.
- __set_PRIMASK(0) should be called because on H7 the built-in ST DFU
  bootloader exits with IRQs disabled.

Signed-off-by: Damien George <damien@micropython.org>
This commit is contained in:
Damien George 2022-01-31 16:47:03 +11:00
parent c99ed8d6fa
commit c8c229b96c
1 changed files with 33 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

42
ports/stm32/mboot/main.c
View File

@ -265,27 +265,48 @@ void SystemClock_Config(void) {
while (__HAL_RCC_GET_FLAG(RCC_FLAG_PLLRDY) != RESET) {
}
// Configure PLL1 factors and source
RCC->PLLCKSELR =
MICROPY_HW_CLK_PLLM << RCC_PLLCKSELR_DIVM1_Pos
| 2 << RCC_PLLCKSELR_PLLSRC_Pos; // HSE selected as PLL source
// Disable PLL3
__HAL_RCC_PLL3_DISABLE();
while (__HAL_RCC_GET_FLAG(RCC_FLAG_PLL3RDY) != RESET) {
}
// Select HSE as PLLx source
RCC->PLLCKSELR = 2 << RCC_PLLCKSELR_PLLSRC_Pos;
RCC->PLLCFGR = 0;
// Configure PLL1 for use by SYSCLK
RCC->PLLCKSELR |= MICROPY_HW_CLK_PLLM << RCC_PLLCKSELR_DIVM1_Pos;
RCC->PLLCFGR |= RCC_PLLCFGR_DIVP1EN;
RCC->PLL1FRACR = 0;
RCC->PLL1DIVR =
(MICROPY_HW_CLK_PLLN - 1) << RCC_PLL1DIVR_N1_Pos
| (MICROPY_HW_CLK_PLLP - 1) << RCC_PLL1DIVR_P1_Pos // only even P allowed
| (MICROPY_HW_CLK_PLLQ - 1) << RCC_PLL1DIVR_Q1_Pos
| (MICROPY_HW_CLK_PLLR - 1) << RCC_PLL1DIVR_R1_Pos;
// Enable PLL1 outputs for SYSCLK and USB
RCC->PLLCFGR = RCC_PLLCFGR_DIVP1EN | RCC_PLLCFGR_DIVQ1EN;
// Configure PLL3 for use by USB at Q=48MHz
RCC->PLLCKSELR |= MICROPY_HW_CLK_PLL3M << RCC_PLLCKSELR_DIVM3_Pos;
RCC->PLLCFGR |= RCC_PLLCFGR_DIVQ3EN;
RCC->PLL3FRACR = 0;
RCC->PLL3DIVR =
(MICROPY_HW_CLK_PLL3N - 1) << RCC_PLL3DIVR_N3_Pos
| (MICROPY_HW_CLK_PLL3P - 1) << RCC_PLL3DIVR_P3_Pos // only even P allowed
| (MICROPY_HW_CLK_PLL3Q - 1) << RCC_PLL3DIVR_Q3_Pos
| (MICROPY_HW_CLK_PLL3R - 1) << RCC_PLL3DIVR_R3_Pos;
// Select PLL1-Q for USB clock source
RCC->D2CCIP2R |= 1 << RCC_D2CCIP2R_USBSEL_Pos;
// Select PLL3-Q for USB clock source
MODIFY_REG(RCC->D2CCIP2R, RCC_D2CCIP2R_USBSEL, RCC_D2CCIP2R_USBSEL_1);
// Enable PLL1
__HAL_RCC_PLL_ENABLE();
while(__HAL_RCC_GET_FLAG(RCC_FLAG_PLLRDY) == RESET) {
}
// Enable PLL3
__HAL_RCC_PLL3_ENABLE();
while(__HAL_RCC_GET_FLAG(RCC_FLAG_PLL3RDY) == RESET) {
}
// Increase latency before changing SYSCLK
if (MICROPY_HW_FLASH_LATENCY > (FLASH->ACR & FLASH_ACR_LATENCY)) {
__HAL_FLASH_SET_LATENCY(MICROPY_HW_FLASH_LATENCY);
@ -320,7 +341,7 @@ void SystemClock_Config(void) {
;
// Update clock value and reconfigure systick now that the frequency changed
SystemCoreClock = CORE_PLL_FREQ;
SystemCoreClockUpdate();
systick_init();
}
@ -1486,6 +1507,9 @@ enter_bootloader:
// set the system clock to be HSE
SystemClock_Config();
// Ensure IRQs are enabled (needed coming out of ST bootloader on H7)
__set_PRIMASK(0);
#if USE_USB_POLLING
// irqs with a priority value greater or equal to "pri" will be disabled
// "pri" should be between 1 and 15 inclusive