USART1 problem to setup without configurator

[VSimo.18]

Hi at everyone,

I need to write a code without the Cube IDE configurator, due to save program memory. I tryed to configure the USAR1, but seem not output on the pin the data streem. Seem that the machine runs because, at the first, I tryed to transmit in polling mode cheching the TXE flag to charge the the TDR register, but not data goes to the pin, but rather, the TX pin seem on high impedence. I forgot something.

Below the USART init :

RCC_CCIPR &= 0xfffffffc; //USART1 clock on system clock
RCC_APBENR2 |= 0x00004000; //USART1 clock enable
RCC_IOPENR |= 0x00000005; //GPIOC clock enable

PORTC_MODER &= 0xefffffff; //set PC14 as alternate function
PORTC_AFRH &= 0xf0ffffff; //set PC14 as TxD function
PORTC_OTYPER &= 0xffffbfff; //PC14 PP mode

USART1_CR1 |= 0x00000001; //USART1 enabled
USART1_CR1 &= 0xefffefff; //8 bit data length
USART1_CR3 = 0x00002000; //DMA disable
USART1_BRR = 0x000001a1; //115200

USART1_CR1 |= 0x00000008; //TX enabled
// USART1_CR1 |= 0x00000004; //RX enabled

The TXD pin is on GPIOC14

then into the main program call every 1 second the follow procedure:
void uart_polling_send(const uint8_t *pData, uint16_t Size, uint16_t Timeout)
{
const uint8_t  *pdata8bits;

pdata8bits  = pData;

//USART1_CR1 |= 0x00000008; //TX enabled

    while(Size > 0U)
    {
PORTC_ODR ^= 0x8000;
    while((USART1_ISR & 0x00000080) == 0) //check TXE flag
    {
    //here will manage the timeout
    }

        USART1_TDR = (uint8_t)(*pdata8bits & 0xFFU);
        pdata8bits++;
    Size--;
    }
while((USART1_ISR & 0x00000040) == 0) //check TC flag
{
//here will manage the timeout
}
}

Using the "PORTC_ODR ^= 0x8000;" instuction I can check how many time execute and how is the execution time (using an oscilloscope). Seem works the flow into the procedure, but as I say the peripheral pin not work. Why?

Thank you at all!

Valter

[Andrew Neil]

Welcome to the forum.

Please see How to write your question to maximize your chances to find a solution; in particular How to insert source code.

You haven't said what chip you're using, or what board it's on.

Please also show the complete code.

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@VSimo.18 wrote:

I need to write a code without the Cube IDE configurator, due to save program memory.

---

Have you tried with the configurator first ?

You could take that as your basis, and then optimise it if required...

[Tesla DeLorean]

Dump the registers for GPIOx and RCC, so you know what's in them

Don't use RMW on the SAME register on multiple lines, it's NOT efficient

Use USART1_CR1 = (USART1_CR1 & ~clear_bits) | set_bits; // so the compile can fold the operation

Don't immediately touch the peripheral who's clock you've enabled, reorder things, say enable GPIOA/GPIOC clocks, then USART1 clock, then touch GPIOC->xx registers, so you've given the pipeline/write-buffer a chance to work.

Correctly comment the lines

Initialize PC15 properly as a OUTPUT-PP, be aware PC13..15 have LOW CURRENT drivers

[VSimo.18]

Hi Andrew,
yes I tryed with configurator and works, but the code to big.
the coplete code is the main file into it is called the USART1_init, and after into the "while(1)" is called the uart_polling_send to send data out of the USART.
could you see any mistake o maybe some lacke in the init flow. I read the data sheet more then one time and I verified to need
enable USART cloc,.
enable GPIOC clock,
select USART clock on SYSClock is on default, but I forced it in any case,
select PC14 as alternate function.
select AF0 (USART1),
select PC14 as push-pull (I don't know if necessary),
enable UART1,
set USART1 without fifo,
enable TX.....

but the PC14 stays on high inpedenze.
Notice, if I comment the "select PC14 as alternate function", it possible to drive the PC14 writing on ODR register, otherwise PC14 isn't driven. Seem the select PC14 as alternate function works, bat because the fisical pin is on high inpedence? I don't understud.

Note:

Thank you of "Please see How to write your question to maximize your chances to find a solution; in particular How to insert source code.", and sorry.

Valter

[Tesla DeLorean]

0x4000 would be PC14

0x8000 is PC15, ie (1 << 15)

[Andrew Neil]

---

@VSimo.18 wrote:

yes I tryed with configurator and works,

---

So compare & contrast what your code does against what the conifgurator's code does.

Or just take the configurator's code, and cut it down to your requirements.

[VSimo.18]

Yes I use UART1_TX on PC14.

I try to follow your previous advises.

Valter

[VSimo.18]

Yes I thinked to do in this way, but it is the first time that I use a STM and the CUBE, and it is not frendly for me, instede I use to use directly the registers (on Renesas, Microchip and Motorola, in the past, 32 bits MCU).
In the project builded with the configurator I send all the registers value to the USART, and seem are the same that I set "manually".
But as I said into the polling procedure seem to works correctly, as the clock is preset and the registers are correct. That is very strange is that the TX pin, connected to the oscilloscope, not show anyting, rather if touched by finger show as it is high impedenze. As if it is not connected to the peripheral.

Valter