Is there any pre-requirments on using PC0 & PC1 as GPIO PP in STM8L051?

[SSin.1]

Hi all,

I am trying to use STM8L051 port c pin 0 as an output to drive a NPN. But I find that PC0 & PC1 cannot be set by using ST HAL library. All the registers seems ok (DDR, ODR, CR1 & CR2). And PC4,5,6 can be driven. Can anyone please give me a hand by providing some hints? AHere are the code:

#include "stm8l15x.h"
#include "main.h"
 
void delay_ms(uint16_t u16_ms)
{
  for(uint16_t u16_a = 0; u16_a < u16_ms; u16_a++)
  {
    for(unsigned short u8_a = 0; u8_a < 37; u8_a++)
    {
      nop();
    }
  }
}
                 
void main(void)
{
  CLK_SYSCLKDivConfig(CLK_SYSCLKDiv_64);
 
  /* Select HSI as system clock source */
  CLK_SYSCLKSourceSwitchCmd(ENABLE);
  CLK_SYSCLKSourceConfig(CLK_SYSCLKSource_HSI); // CLK_SYSCLKSource_HSI
 
  while (CLK_GetSYSCLKSource() != CLK_SYSCLKSource_HSI);
  
  GPIO_Init(GPIOC,GPIO_Pin_0|GPIO_Pin_1|GPIO_Pin_4|GPIO_Pin_5|GPIO_Pin_6, GPIO_Mode_Out_PP_Low_Slow);
  while(1)
  {    
    GPIO_SetBits(GPIOC,GPIO_Pin_0|GPIO_Pin_1|GPIO_Pin_4|GPIO_Pin_5|GPIO_Pin_6);
    delay_ms(1000);
    GPIO_ResetBits(GPIOC,GPIO_Pin_0|GPIO_Pin_1|GPIO_Pin_4|GPIO_Pin_5|GPIO_Pin_6);
    delay_ms(1000);
  }
}

[Peter BENSCH]

Welcome, @SSin.1​, to the community!

For NPN you need an open-drain output. If you initialise the pins in line 25 as PP (push-pull), however, you logically have a push-pull output and no open-drain.

For initialisation instead of

GPIO_Mode_Out_PP_Low_Slow

please use e.g.

GPIO_Mode_Out_OD_HiZ_Slow

Hope that helps?

Regards

/Peter

[SSin.1]

Thanks for your help.

Sorry for my poor explaination, what I mean is something tlike this:

[Peter BENSCH]

Oh, I thought by NPN you meant an NPN of a PLC.

Please try it and replace

GPIO_SetBits(GPIO_TypeDef* GPIOx, uint8_t GPIO_Pin)

by

GPIO_WriteHigh(GPIO_TypeDef* GPIOx, GPIO_Pin_TypeDef PortPins)

...and accordingly for GPIO_ResetBits --> GPIO_WriteLow.

Please note that GPIO_SetBits and GPIO_ResetBits with uint8_t requires a different type for the GPIO_Pin than GPIO_WriteHigh and GPIO_WriteLow (GPIO_Pin_TypeDef).

Regards

/Peter

[SSin.1]

Dear Peter,

Thanks a lot! But can you please kindly tell me where can I get the lastest ST offical HAL w/ GPIO_WriteHigh function? The version on my hand is v1.6.1, which doesn't contain GPIO_WriteHigh.

  * @file    stm8l15x_gpio.c
  * @author  MCD Application Team
  * @version V1.6.1
  * @date    30-September-2014

BTW, GPIO_SetBits has just one line

void GPIO_SetBits(GPIO_TypeDef* GPIOx, uint8_t GPIO_Pin)
{
  GPIOx->ODR |= GPIO_Pin;
}

And it can change ODR. So what can I do to modity the function to make it works? Thanks.

[Peter BENSCH · Accepted solution]

Oops, sorry, I got it mixed up with the STM8S family library.

You are right, of course, but you should take into account that on the STM8L051 exactly two pins are so-called true open drain ports - PC0 and PC1. The RM0031 writes about this:

In the true open-drain I/Os, P-Buffer, weak pull-up and protection diode to VDD is not implemented.

This means: to drive an H-level at the output, you must connect an external pull-up, which provides the driving current for your npn BRT.

Regards

/Peter

[SSin.1]

Dear Peter,

Thanks a lot! sorry for missing such a point!