Ch8 UART and Terminal

[olivier.cornez@me.com]

Hi,
I am on OS X 10.10 and the terminal does not work in Eclipse Neon 2.
Msg is kermit command unknown while it works fine in os x terminal.

I decided to use CoolTerm but I get strange output when I use HAL_UART_Transmit_IT:
output like this “…….**…..#……………..”
It seems the txBuf points to an unallocated memory address.
I try to debug but cannot figure out what is going on the terminal output seems not to match what i can see in debug window inside Eclipse (pData is correct in debug)???

Could somebody help?

[Carmine Noviello]

What about the terminal speed? Does it match the UART baudrate? XOR/XOFF, parity, bits?!?

[olivier.cornez@me.com]

Yes terminal speed matches (115200 – 8 – 1 – N default setup from CubeMX)
The HAL_UART_Transmit works fine, the Receive_IT works fine but only HAL_UAT_Transmit_IT produces strange outputs.

[Carmine Noviello]

Do you properly wait for transmit completion before calling again the HAL_UART_Transmit_IT()? If not, the transmit buffer is overridden. The CPU is much faster than the UART.

[olivier.cornez@me.com]

I am using the example from the book with the ringBuffer.
right now I modified the code to use only once the UART_Transmit function for the prompt and it seems to work.
But if I use several call s to UART_Transmit inside the processInput() then I get strange outputs

[olivier.cornez@me.com]

Hi,

As far as I understand the problem comes with the msg.
If it stores only 1 character as in your book example it works fine but if I change the message then I get strange output like this

Welcome to the Nucleo management console
Select the option you are interested in:
.1. Toggle LD2 LED
.2. Read USER BUTTON status
.3. Clear screen and print this message
Selection: > You sele….Ë…∫…˛..
Selection: > Yo….ˇˇ….Ë…….˛..
Selection: > Yo….ˇˇ….Ë…….˛P.
Selection: > You sele….Ë…….˛..
Selection: > Yo..˘ˇˇˇˇ…Ë……….
Selection: >

uint8_t processUserInput(uint8_t opt) {
char msg[30];

if(!(opt >= 1 && opt <= 3))
return 0;

//sprintf(msg, “%d”, opt);
sprintf(msg, “You selected option %d\r\n”, opt);

UART_Transmit(&huart2, (uint8_t*)msg, strlen(msg));

switch(opt) {
case 1:
HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_5);
break;
case 2:
sprintf(msg, “\r\nUSER BUTTON status: %s”, HAL_GPIO_ReadPin(GPIOC, GPIO_PIN_13) == GPIO_PIN_RESET ? “PRESSED” : “RELEASED”);

As far as I understand if the UART is not HAL_BUZY the UART_Transmit() directly the first char while if HAL_BUZY it stores the string in the txBuf.
After that point I am not sure…
What is going on with the next call to

void HAL_UART_TxCpltCallback(UART_HandleTypeDef *huart){
//trace_puts(“UART Tx IT Complete\n”);
if(RingBuffer_GetDataLength(&txBuf) > 0){
RingBuffer_Read(&txBuf, &txData, 1);
HAL_UART_Transmit_IT(huart, &txData, 1);
}
}

Could you clarify this to help?

Thank you so much

[Skalibur]

I have the same problem.

Without interrupt no have problem, but with interrupt I need to increase CPU clock above to 48Mhz.

[olivier.cornez@me.com]

As far as understand is related to msg array being out of scope when using interlocks.
If you move the msg[30] to a global scope then it works fine for me.
Note: I was also getting wrong info from the debugger not flashing the firmware on restart.

[Author]

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