stm32f100 usart not working properly

[kkada]

Hi,

I am working on stm32f100 48 pin device.I am having operational issue while working on usart.

my hw configured to use internal hsi osc which further add pll to generate sysclk of 36Mhz.I am communicating to gsm module over usart3.issue is gsm module not accepting any commands.though i can see responses from module when power on/off.so i tried using loop back test on controller.i found in live watch some data is getting skipped.

other way round i also tested using cp2102 usb to ttl module to check if micro controller transmits command or not.on putty i dont see any commands from controller.

my question---what is maximum clock can be generated using hsi?

how much we can rely on internal osc integrity?? as you suggest some calibration methods

internal osc setting affect baud rate generator?

I have checked gsm module using cp2102 and its working pretty fine.

thanks .

kiran kadam

[kkada]

Hi @Community member​  i would like to show you one analysis.please find below change in usart initialization

this triggers interrupt on receive line continuously.though null bytes stream received.

didn't get this behavior?

USART_DeInit(USART3);

 USART_InitStructure.USART_WordLength = USART_WordLength_8b;

 USART_InitStructure.USART_StopBits = USART_StopBits_1;

 USART_InitStructure.USART_Parity = USART_Parity_No;

 USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;//USART_HardwareFlowControl_RTS_CTS;

 USART_InitStructure.USART_Mode = USART_Mode_Rx ;//| USART_Mode_Tx;

thanks