STM32L0 I2C Slave, hotplug Issue
Hello,
I'm working on a product where we will use the STM32L71 device containing an I2C Interface for servicing and control. I develop first parts of the firmware on a STM32L53 nucleo board. Since the device must be hot-pluggable, it is not allowed to influence the I2C bus, by pulling the SCL or SDA lines to ground while power-on. In general no problem for STM32L0, because of open drain I2C. But I've seen it happens while the initialization of IO used for I2C and it's unfortunately not acceptable for our product.
I've found a way to fix it. Dropping the lines (for 2.75µs) to ground was caused while "LL_GPIO_SetPinMode" function which was called while LL_GPIO_Init for I2C. I could fix this by placing the LL_GPIO_SetPinMode after the "LL_GPIO_SetAFPin_8_15".
Now it seems to work.
There is the complete change of LL_GPIO_Init function (stm32l0xx_ll_gpio.h generated by Cube MX V4.25.1)
Before fix (line 25):
ErrorStatus LL_GPIO_Init(GPIO_TypeDef *GPIOx, LL_GPIO_InitTypeDef *GPIO_InitStruct)
{
uint32_t pinpos = 0x00000000U;
uint32_t currentpin = 0x00000000U;
/* Check the parameters */
assert_param(IS_GPIO_ALL_INSTANCE(GPIOx));
assert_param(IS_LL_GPIO_PIN(GPIO_InitStruct->Pin));
assert_param(IS_LL_GPIO_MODE(GPIO_InitStruct->Mode));
assert_param(IS_LL_GPIO_PULL(GPIO_InitStruct->Pull));
/* ------------------------- Configure the port pins ---------------- */
/* Initialize pinpos on first pin set */
/* pinpos = 0; useless as already done in default initialization */
/* Configure the port pins */
while (((GPIO_InitStruct->Pin) >> pinpos) != 0x00000000U)
{
/* Get current io position */
currentpin = (GPIO_InitStruct->Pin) & (0x00000001U << pinpos);
if (currentpin)
{
/* Pin Mode configuration */
LL_GPIO_SetPinMode(GPIOx, currentpin, GPIO_InitStruct->Mode);
if ((GPIO_InitStruct->Mode == LL_GPIO_MODE_OUTPUT) || (GPIO_InitStruct->Mode == LL_GPIO_MODE_ALTERNATE))
{
/* Check Speed mode parameters */
assert_param(IS_LL_GPIO_SPEED(GPIO_InitStruct->Speed));
/* Speed mode configuration */
LL_GPIO_SetPinSpeed(GPIOx, currentpin, GPIO_InitStruct->Speed);
}
/* Pull-up Pull down resistor configuration*/
LL_GPIO_SetPinPull(GPIOx, currentpin, GPIO_InitStruct->Pull);
if (GPIO_InitStruct->Mode == LL_GPIO_MODE_ALTERNATE)
{
/* Check Alternate parameter */
assert_param(IS_LL_GPIO_ALTERNATE(GPIO_InitStruct->Alternate));
/* Speed mode configuration */
if (currentpin < LL_GPIO_PIN_8)
{
LL_GPIO_SetAFPin_0_7(GPIOx, currentpin, GPIO_InitStruct->Alternate);
}
else
{
LL_GPIO_SetAFPin_8_15(GPIOx, currentpin, GPIO_InitStruct->Alternate);
}
}
}
pinpos++;
}After fix (line 52):
ErrorStatus LL_GPIO_Init(GPIO_TypeDef *GPIOx, LL_GPIO_InitTypeDef *GPIO_InitStruct)
{
uint32_t pinpos = 0x00000000U;
uint32_t currentpin = 0x00000000U;
/* Check the parameters */
assert_param(IS_GPIO_ALL_INSTANCE(GPIOx));
assert_param(IS_LL_GPIO_PIN(GPIO_InitStruct->Pin));
assert_param(IS_LL_GPIO_MODE(GPIO_InitStruct->Mode));
assert_param(IS_LL_GPIO_PULL(GPIO_InitStruct->Pull));
/* ------------------------- Configure the port pins ---------------- */
/* Initialize pinpos on first pin set */
/* pinpos = 0; useless as already done in default initialization */
/* Configure the port pins */
while (((GPIO_InitStruct->Pin) >> pinpos) != 0x00000000U)
{
/* Get current io position */
currentpin = (GPIO_InitStruct->Pin) & (0x00000001U << pinpos);
if (currentpin)
{
if ((GPIO_InitStruct->Mode == LL_GPIO_MODE_OUTPUT) || (GPIO_InitStruct->Mode == LL_GPIO_MODE_ALTERNATE))
{
/* Check Speed mode parameters */
assert_param(IS_LL_GPIO_SPEED(GPIO_InitStruct->Speed));
/* Speed mode configuration */
LL_GPIO_SetPinSpeed(GPIOx, currentpin, GPIO_InitStruct->Speed);
}
/* Pull-up Pull down resistor configuration*/
LL_GPIO_SetPinPull(GPIOx, currentpin, GPIO_InitStruct->Pull);
if (GPIO_InitStruct->Mode == LL_GPIO_MODE_ALTERNATE)
{
/* Check Alternate parameter */
assert_param(IS_LL_GPIO_ALTERNATE(GPIO_InitStruct->Alternate));
/* Speed mode configuration */
if (currentpin < LL_GPIO_PIN_8)
{
LL_GPIO_SetAFPin_0_7(GPIOx, currentpin, GPIO_InitStruct->Alternate);
}
else
{
LL_GPIO_SetAFPin_8_15(GPIOx, currentpin, GPIO_InitStruct->Alternate);
}
}
/* Pin Mode configuration */
LL_GPIO_SetPinMode(GPIOx, currentpin, GPIO_InitStruct->Mode);
}
pinpos++;
}
if ((GPIO_InitStruct->Mode == LL_GPIO_MODE_OUTPUT) || (GPIO_InitStruct->Mode == LL_GPIO_MODE_ALTERNATE))
{
/* Check Output mode parameters */
assert_param(IS_LL_GPIO_OUTPUT_TYPE(GPIO_InitStruct->OutputType));
/* Output mode configuration*/
LL_GPIO_SetPinOutputType(GPIOx, GPIO_InitStruct->Pin, GPIO_InitStruct->OutputType);
}
return (SUCCESS);
}Could you confirm please if it's OK? I mean could this fix have some negative influence to other IO initialization routines while I2C seems to work proper now?
Best Regards
