Aksal/nuttx
3
1
Fork 1
mirror of https://github.com/apache/nuttx.git synced 2026-08-22 14:08:30 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 2

arm/stm32: Fix the USB reset sequence in arm_usbinitialize().

Browse source 
The code that claimed to "enable clocking to the USB peripheral" cleared
RCC_APB1ENR_USBEN inside RCC_APB1RSTR.  That is both the wrong register
and the wrong bit: USBEN belongs to RCC_APB1ENR, while APB1RSTR holds
RCC_APB1RSTR_USBRST.  The peripheral clock is enabled by the RCC setup
performed at boot, so the write had no useful effect and merely cleared
an unrelated reset bit.

Issue a proper reset pulse on RCC_APB1RSTR_USBRST instead, so the
controller starts from a known state.

On STM32L0 the D+/D- lines are connected to the USB transceiver
automatically once the peripheral is enabled and there is no alternate
function to select, so skip the GPIO configuration on that chip.  The
board GPIO_USB_DM/GPIO_USB_DP definitions do not exist there.

Assisted-by: GitHub Copilot:claude-opus-5
Signed-off-by: jsanchez-2g <jsanchez@2g-eng.com>
This commit is contained in:
jsanchez-2g 2026-08-18 14:35:17 -05:00 • committed by Xiang Xiao
parent fc05091e18
commit d70725e4e0
1 changed files with 5 additions and 6 deletions
Download patch file Download diff file Expand all files Collapse all files

11
arch/arm/src/common/stm32/stm32_usbdev_m0_v1.c
View file

@ -3684,20 +3684,19 @@ void arm_usbinitialize(void)
*/
struct stm32_usbdev_s *priv = &g_usbdev;
uint32_t regval;
usbtrace(TRACE_DEVINIT, 0);
/* Configure USB GPIO alternate function pins */
#ifndef CONFIG_STM32_STM32L0
stm32_configgpio(GPIO_USB_DM);
stm32_configgpio(GPIO_USB_DP);
#endif
/* Enable clocking to the USB peripheral */
/* Reset the USB peripheral */
regval = getreg32(STM32_RCC_APB1RSTR);
regval &= ~RCC_APB1ENR_USBEN;
putreg32(regval, STM32_RCC_APB1RSTR);
modifyreg32(STM32_RCC_APB1RSTR, 0, RCC_APB1RSTR_USBRST);
modifyreg32(STM32_RCC_APB1RSTR, RCC_APB1RSTR_USBRST, 0);
/* Power up the USB controller, but leave it in the reset state */