LPUART LL driver not working, HAL driver working (STM32L476JG)

[Alex Hösl]

Posted on April 04, 2018 at 17:00

Hi everybody,

I'm currently facing the following problem: I initialize code with CubeMX for a STM32L476JG. I want to use the low level drivers, but they don't seem to work. I was doing several hours of testing and trying to find the error, but don't come further anymore.

My last try was to switch to the HAL drivers for a simple test, voila, it's working! Immediately, without any problems!

But I need the LL drivers. Maybe somebody can help me!

This is how Cube initialises the LPUART with LL drivers:

/* LPUART1 init function */
static void MX_LPUART1_UART_Init(void)
{
 LL_LPUART_InitTypeDef LPUART_InitStruct;
 LL_GPIO_InitTypeDef GPIO_InitStruct;
 /* Peripheral clock enable */
 LL_APB1_GRP2_EnableClock(LL_APB1_GRP2_PERIPH_LPUART1);
 
 /**LPUART1 GPIO Configuration 
 PB11 ------> LPUART1_TX
 PB12 ------> LPUART1_RTS
 PB13 ------> LPUART1_CTS
 PB10 ------> LPUART1_RX 
 */
 GPIO_InitStruct.Pin = LL_GPIO_PIN_11|LL_GPIO_PIN_12|LL_GPIO_PIN_13|LL_GPIO_PIN_10;
 GPIO_InitStruct.Mode = LL_GPIO_MODE_ALTERNATE;
 GPIO_InitStruct.Speed = LL_GPIO_SPEED_FREQ_VERY_HIGH;
 GPIO_InitStruct.OutputType = LL_GPIO_OUTPUT_PUSHPULL;
 GPIO_InitStruct.Pull = LL_GPIO_PULL_NO;
 GPIO_InitStruct.Alternate = LL_GPIO_AF_8;
 LL_GPIO_Init(GPIOB, &GPIO_InitStruct);
 /* LPUART1 DMA Init */
 
 /* LPUART_TX Init */
 LL_DMA_SetPeriphRequest(DMA2, LL_DMA_CHANNEL_6, LL_DMA_REQUEST_4);
 LL_DMA_SetDataTransferDirection(DMA2, LL_DMA_CHANNEL_6, LL_DMA_DIRECTION_MEMORY_TO_PERIPH);
 LL_DMA_SetChannelPriorityLevel(DMA2, LL_DMA_CHANNEL_6, LL_DMA_PRIORITY_MEDIUM);
 LL_DMA_SetMode(DMA2, LL_DMA_CHANNEL_6, LL_DMA_MODE_NORMAL);
 LL_DMA_SetPeriphIncMode(DMA2, LL_DMA_CHANNEL_6, LL_DMA_PERIPH_NOINCREMENT);
 LL_DMA_SetMemoryIncMode(DMA2, LL_DMA_CHANNEL_6, LL_DMA_MEMORY_INCREMENT);
 LL_DMA_SetPeriphSize(DMA2, LL_DMA_CHANNEL_6, LL_DMA_PDATAALIGN_BYTE);
 LL_DMA_SetMemorySize(DMA2, LL_DMA_CHANNEL_6, LL_DMA_MDATAALIGN_BYTE);
 /* LPUART1 interrupt Init */
 NVIC_SetPriority(LPUART1_IRQn, NVIC_EncodePriority(NVIC_GetPriorityGrouping(),5, 0));
 NVIC_EnableIRQ(LPUART1_IRQn);
 LPUART_InitStruct.BaudRate = 9600;
 LPUART_InitStruct.DataWidth = LL_LPUART_DATAWIDTH_8B;
 LPUART_InitStruct.StopBits = LL_LPUART_STOPBITS_1;
 LPUART_InitStruct.Parity = LL_LPUART_PARITY_NONE;
 LPUART_InitStruct.TransferDirection = LL_LPUART_DIRECTION_TX_RX;
 LPUART_InitStruct.HardwareFlowControl = LL_LPUART_HWCONTROL_NONE;
 LL_LPUART_Init(LPUART1, &LPUART_InitStruct);
}

After that, I was trying to send some data (doesn't work). Am I missing something?:

 while(1)
 {
 LL_LPUART_TransmitData8(LPUART1, 0x55);
 myTimer_CPU_Delay(10);
 }

And that's how Cube initialises with HAL drivers:

/* LPUART1 init function */
static void MX_LPUART1_UART_Init(void)
{
 hlpuart1.Instance = LPUART1;
 hlpuart1.Init.BaudRate = 9600;
 hlpuart1.Init.WordLength = UART_WORDLENGTH_8B;
 hlpuart1.Init.StopBits = UART_STOPBITS_1;
 hlpuart1.Init.Parity = UART_PARITY_NONE;
 hlpuart1.Init.Mode = UART_MODE_TX_RX;
 hlpuart1.Init.HwFlowCtl = UART_HWCONTROL_NONE;
 hlpuart1.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
 hlpuart1.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
 if (HAL_UART_Init(&hlpuart1) != HAL_OK)
 {
 _Error_Handler(__FILE__, __LINE__);
 }
}

And I can successfully transmit after that with the following:

 uint8_t data = 0x55;
 while(1)
 {
 HAL_UART_Transmit(&hlpuart1, &data, sizeof(data), 100);
 myTimer_CPU_Delay(10);
 }

I would appreciate a tipp, hint, solution! If you need further information, I'm sure I'll find them.

Thanks in advance,

Regards

Alex

#ll-uart #uart #lpuart #ll-drivers #hal-versus-ll-drivers #hal-uart #stm32-l4

[Tesla DeLorean · Accepted solution]

Posted on April 04, 2018 at 19:25

Make sure you enable the GPIO bank clocks for the pins involved before initializing them.

LL_AHB2_GRP1_EnableClock(LL_AHB2_GRP1_PERIPH_GPIOB);

Use a debugger Peripheral View to check register settings in RCC, GPIO and LPUART1

[Alex Hösl]

Posted on April 05, 2018 at 09:43

Thanks a lot!

I checked the register settings and compared LL to HAL.

The HAL LPUART is enabled after initialisation, the LL doesn't enable LPUART (CR1 bit0). I manually called the LL_LPUART_Enable() function and now it works.

I'm wondering why this is necessary. When I used the LL drivers of USART on a similar MCU it wasn't necessary. Maybe this is one of the low power functionalities?! The LL USART CubeMX code enables UART at the end of the initialisation:

...

  LL_USART_Init(USART2, &USART_InitStruct);

  LL_USART_ConfigAsyncMode(USART2);

  LL_USART_Enable(USART2);

}

The LL LPUART ends with the LL_LPUART_Init() function.

For me the problem is solved, thanks again!

[Amel NASRI]

Posted on April 05, 2018 at 13:40

Hi

alexander.hoesl

‌,

The call of

LL_LPUART_Enable()

has to be available in the generated project by STM32CubeMX.

I will log this issue to our STM32CubeMX team.

-Amel

[Amel NASRI]

Posted on July 06, 2018 at 14:32

Please note that a call of 

LL_LPUART_Enable is added in code generated by the last CubeMX version (V4.26).

6amel

[DSwar.1]

Good day,

I have encountered this same issue where LL_LPUART_Enable() is missing from the code generated by CubeMX and I have version 5.6.0

Regards,

Dylan.

[Amel NASRI]

Hello @DSwar.1​ ,

I cannot reproduce the issue on my side. Could you please share your .ioc file?

Thanks,

Amel