Solved
STM32F4xx USB bug, when compiled by GCC using -O3 option.
Setup:
Project, generated by CubeMX and compiled by arm-none-eabi-gcc-9.2.0 toolchain.
CubeMX firmware package version: STM32Cube FW_L4 V1.14.0
CPU: STM32L432KCY (and others)
Toolchain: arm-none-eabi-gcc-9.2.0 (and others)
Compiler options: -mcpu=cortex-m4 -mthumb -mfloat-abi=softfp -mfpu=fpv4-sp-d16 -O3 -fmessage-length=0 -fsigned-char -ffunction-sections -fdata-sections -fno-inline-functions
Problem:
Usb not working properly.
Solution:
FunctionUSB_WritePMA, not working properly when project compiled using -O3 optimization option. Let's look at the file stm32l4xx_ll_usb.c. Pls. look at the function
/**
* @brief Copy a buffer from user memory area to packet memory area (PMA)
* @param USBx USB peripheral instance register address.
* @param pbUsrBuf pointer to user memory area.
* @param wPMABufAddr address into PMA.
* @param wNBytes: no. of bytes to be copied.
* @retval None
*/
void USB_WritePMA(USB_TypeDef *USBx, uint8_t *pbUsrBuf, uint16_t wPMABufAddr, uint16_t wNBytes)
{
uint32_t n = ((uint32_t)wNBytes + 1U) >> 1;
uint32_t BaseAddr = (uint32_t)USBx;
uint32_t i, temp1, temp2;
uint16_t *pdwVal; // Fix: make it volatile // volatile uint16_t *pdwVal;
uint8_t *pBuf = pbUsrBuf;
pdwVal = (uint16_t *)(BaseAddr + 0x400U + ((uint32_t)wPMABufAddr * PMA_ACCESS));
for (i = n; i != 0U; i--)
{
temp1 = (uint16_t) * pBuf;
pBuf++;
temp2 = temp1 | ((uint16_t)((uint16_t) * pBuf << 8));
*pdwVal = (uint16_t)temp2;
pdwVal++;
#if PMA_ACCESS > 1U
pdwVal++;
#endif
pBuf++;
}
}volatile uint16_t *pdwVal;After fix:
