STM32L4xx I2C Interrupts

[DPyke]

Please can you help me. I cannot use the HAL as I have to write an ultra low power/ minimalist application. I need to Tx/Rx a few bytes over I2C3 . I have set it up as below but I do not get any interrupts, either event or errors. Can you tell me what I am doing wrong, thank you

I am setting up the I2C interface :

RCC->APB1ENR1 |= RCC_APB1ENR1_I2C3EN;

I2C3->CR1 = (I2C_CR1_WUPEN|I2C_CR1_ERRIE|I2C_CR1_TCIE|I2C_CR1_TXI|I2C_CR1_STOPIE);

I2C3->CR2 = ( I2C_CR2_AUTOEND);

I2C3->TIMINGR = ((0x00000000 & ~(I2C_TIMINGR_PRESC_Msk|I2C_TIMINGR_SCLDEL_Msk|I2C_TIMINGR_SDADEL_Msk|I2C_TIMINGR_SCLH_Msk|I2C_TIMINGR_SCLL_Msk))\

|( 0x03 << I2C_TIMINGR_PRESC_Pos)\

|( 0x04 << I2C_TIMINGR_SCLDEL_Pos)\

|( 0x02 << I2C_TIMINGR_SDADEL_Pos)\

|( 0x0f << I2C_TIMINGR_SCLH_Pos)\

|( 0x13 << I2C_TIMINGR_SCLL_Pos));

(I do other things too, (I set the GPIO pins to alt Fn)

When I read back the contents of the reg I get)

CR1 = 0x00008023

CR2 = 0x000400e3

ISR = 0x022c2070

To transmit:

RCC->APB1ENR1 |= RCC_APB1ENR1_I2C3EN; // AHB1 Peripheral Clock Enable

I2C3->CR1 |= I2C_CR1_PE;  // I2C3 Enable 

I2C3->CR2 &= ~(I2C_CR2_NBYTES_Msk | I2CADDRESSBITS | I2C_CR2_RD_WRN); // Clear Addr

I2C3->CR2 |= Address; // address of target

I2C3->CR2 |= (NumberOfBytes<<I2C_CR2_NBYTES_Pos); // setup number of bytes

I2C3->TXDR = Data; // Transmit data

I2C3->CR1 |= (I2C_CR1_TXIE|I2C_CR1_TCIE|I2C_CR1_STOPIE|I2C_CR1_ERRIE); // AGAIN!

I2C3->CR2 |= I2C_CR2_START; // START Tx

It successfully transmits one byte @ 100Khz (16MHz operation)

The flags are set but it never goes to I2C3_EV_IRQHandler or I2C3_ER_IRQHandler

Is there global interrupt mask I need to set?

I would appreciated any help, thank you

[waclawek.jan]

NVIC_EnableIRQ(I2C3_EV_IRQn);

NVIC_EnableIRQ(I2C3_ER_IRQn);

JW

PS. You don't need line continuation (backslashes) in C code, only in preprocessor macros (#define).

[After Forever]

Did you enable the interrupt in NVIC? Something like this:

NVIC_SetPriority(I2C3_ER_IRQn, NVIC_EncodePriority(NVIC_GetPriorityGrouping(), 3, 0));

NVIC_EnableIRQ(I2C3_ER_IRQn);

edit: was late :)

[DPyke]

Excellent, thank you for your help, I will give that a ago ASAP

The timers worked fine without setting a priority and when I looked at the I2C3 interrupts it said that there were priority default of 79, 80 ? I will set them manually and hope that brings this to life

Backslashes : I cut and pasted the code from a macro to make it easier to see :)

[DPyke]

I will do this now and let you know what happens, thank you for your assistance :)

Late? this is not a race I am so glad to receive all help

Thanks for your time to write

[DPyke]

I added :

NVIC_EnableIRQ( I2C3_EV_IRQn); // Enable Event interrupts

NVIC_EnableIRQ( I2C3_ER_IRQn); // Enable Error interrupts

and it works! Excellent thank you both.

I have datasheet RM0351 and it does not this information, or I could not find it. What documentation can I find this information from?

All the best

Dren

[After Forever]

See the "Nested vectored interrupt controller (NVIC)" section in the mentioned RM0351.

It will refer you to PM0214 "programming manual" for more information.

[AVI-crak]

This macro reduces errors.

#define _VAL2FLD(field, value)    ((value << field ## _Pos) & field ## _Msk)

An example of using a macro.

    I2C2->TIMINGR = _VAL2FLD( I2C_TIMINGR_PRESC, 9)|        /// Timings prescale
                    _VAL2FLD( I2C_TIMINGR_SCLL, 30)|        /// SCL low period (master mode)
                    _VAL2FLD( I2C_TIMINGR_SCLH, 12)|        /// SCL high period (master mode)
                    _VAL2FLD( I2C_TIMINGR_SDADEL, 3)|       /// Data hold time
                    _VAL2FLD( I2C_TIMINGR_SCLDEL, 12);      /// Data setup time

The documentation has a convenient timing table for several frequency options.