How to write and read an I2C eeprom using stm32f100 board

Question

I' m working in team on a project using stm32 f100 series board. I should use an external I2C eeprom to storage some data, the eeprom is the following: CAT24C512WI-GT3 and I also have the init code for this I2C eeprom:

void io_ee_scl(char s)
{
    if(s)
        GPIOB->BSRR=GPIO_PIN_6;
    else
        GPIOB->BRR=GPIO_PIN_6;
}

void io_ee_sda(char s)
{
    if(s)
        GPIOB->BSRR=GPIO_PIN_7;
    else
        GPIOB->BRR=GPIO_PIN_7;

}

void io_ee_wp(char s)
{
    if(s)
        GPIOB->BSRR=GPIO_PIN_5;
    else
        GPIOB->BRR=GPIO_PIN_5;
}
char read_eeprom()  //read eeprom function
{
    return ( (GPIOB->IDR&GPIO_PIN_7) ? 1 : 0 );
}

On internet the most guide talk about HAL library but as you can see my colleague doesn't use the HAL library and considering I am new in stm32 I don't know how to read and write data on the eeprom. Some suggestions?

score 2 · Answer 1 · answered Jul 24 '19 at 08:56

This is no init code, but a part of the system-specific code for a software-only (a.k.a. bit-banging) I²C driver.

in addition to this, you have to

enable the GPIOB peripheral clock in RCC->APB2ENR
put both pins in open-drain, general purpose output mode in GPIOB->CRL
have a delay function for 1/2 of the I²C clock cycle time, i.e. if it should be running at 100 kHz, a single cycle takes 10 μs, you'd need a delay of 5 μs.

Then it's possible to use general I²C code to communicate with the EEPROM. The communication protocol is described in detail in the EEPROM datasheet.

It is also possible to use the built in I²C peripheral of the STM32F1, but it'd be quite challenging as the first task on this platform for a beginner. Nevertheless, if you'd like to do it, you can study the relevant HAL source code to see how it is done there.

How to write and read an I2C eeprom using stm32f100 board

1 Answers1