8-bit LCD interfacing

[M0nty]

Hi everyone I'm rather new with programming with STM32 controllers and I am currently using NUCLEO-L432KC. Currently I'm facing a problem with HAL_GPIO_WritePin() function. I am interfacing with a 16x2 LCD and I am trying to write to the RS pin via the function I have mentioned, however I am facing a problem where the RS isn't being set to the desired value I am providing. I have provided the value like so: HAL_GPIO_WritePin(RS_GPIO_Port, RS_Pin, rs);

Where I have given rs = 0 but the function is setting the value as 1. I have also provided the photo of the RS pin configuration from the IOC file.

[Andrew Neil]

Welcome to the forum!

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@M0nty wrote:

Hi everyone I'm rather new with programming with STM32 controllers

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Do you have experience with any other microcontroller(s)? With programming in general ?

Please post your source code - instructions here:

https://community.st.com/t5/community-guidelines/how-to-write-your-question-to-maximize-your-chances-to-find-a/ta-p/575228

Also your schematic of how the LCD is connected.

A good, clear photo may also help.

Have you checked the Nucleo board's User Manual and/or schematics to see that nothing else is using that pin?

[Ghofrane GSOURI]

Hello @M0nty 

First let me thank you for posting.

By checking the  HAL_GPIO_WritePin () the parameter :

PinState: specifies the value to be written to the selected bit.

* This parameter can be one of the GPIO_PinState enum values:

* @arg GPIO_PIN_RESET: to clear the port pin

* @arg GPIO_PIN_SET: to set the port pin

Ensure that you are passing the correct value for rs. The PinState parameter should be either

GPIO_PIN_SET or GPIO_PIN_RESET, not just 0 or 1. If you are using a variable like rs, make sure

it is defined as:

GPIO_PinState rs = GPIO_PIN_RESET; // or GPIO_PIN_SET

Instead of:

int rs = 0; // This may cause issues

THX

Ghofrane

[Andrew Neil]

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@Ghofrane GSOURI wrote:

The PinState parameter should be either GPIO_PIN_SET or GPIO_PIN_RESET, not just 0 or 1.e

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The GPIO_PIN_SET and GPIO_PIN_RESET values are 1 and 0 - so it should be OK ...

/** 
  * @brief  GPIO Bit SET and Bit RESET enumeration 
  */
typedef enum
{
  GPIO_PIN_RESET = 0U,
  GPIO_PIN_SET
}GPIO_PinState;

[SofLit]

Hello @M0nty and welcome to the community,

Could you please share your ioc file as well as sharing your code?

[Ghofrane GSOURI]

Hello @Andrew Neil 

Let 's just try to use the parameter value as it is GPIO_PIN_SET or GPIO_PIN_RESET and see what's happen.

THX

Ghofrane

[M0nty]

I have also tried the same thing by substituting rs as GPIO_PIN_RESET but the same issue occurs

[M0nty]

No problem, I have provided my ioc file as requested to help you get a better understanding of my configuration

[M0nty]

I am actually passing rs as an argument from a function call as shown so I'm not sure if this also causes a problem. (Edit: I tried changing the type of argument for rs from int to GPIO_PinState: void send_cmd(char data, GPIO_PinState rs) but this also doesn't work and the same problem occurs.

send_cmd(0x38,0); 
void send_cmd (char data, int rs) 
{ 
 HAL_GPIO_WritePin(RS_GPIO_Port, RS_Pin, rs); 
}

.  

[Andrew Neil]

Time to go back to basics.

Disconnect the LCD.

Go back to a basic "blinky" program which just toggles the LED on the Nucleo board - just a loop with inline delays.

Once that is working, change it to toggle your RS pin.

Does the pin toggle?