understanding the I2C peripheral on STM32L412

[deep_rune]

I want to use the I2C peripheral on my STM32L412C8T6, although I read the reference manual I'm still finding the operation of this peripheral a little confusing. I have a 4 channel I2C 12bit DAC to operate, so I want the I2C to act as a master transmitter in fast mode (400KHz), transmitting first the address then 8 bytes of data which are the 12bit values of 4 channels split over two bytes. I have the clock for the I2C set to 16MHz and the rise and fall times set at 300nS - as per the reference manual.

I've programmed everything as best as I can see how, but my interrupt never runs so I must have been doing something wrong. This is my setup for the I2C -

static void MX_I2C2_Init(void)
{
 hi2c2.Instance = I2C2;
 hi2c2.Init.Timing = 0x00610611;
 hi2c2.Init.OwnAddress1 = 0;
 hi2c2.Init.AddressingMode = I2C_ADDRESSINGMODE_7BIT;
 hi2c2.Init.DualAddressMode = I2C_DUALADDRESS_DISABLE;
 hi2c2.Init.OwnAddress2 = 0;
 hi2c2.Init.OwnAddress2Masks = I2C_OA2_NOMASK;
 hi2c2.Init.GeneralCallMode = I2C_GENERALCALL_DISABLE;
 hi2c2.Init.NoStretchMode = I2C_NOSTRETCH_DISABLE;
 if (HAL_I2C_Init(&hi2c2) != HAL_OK)
 {
 Error_Handler();
 }
 /** Configure Analogue filter 
 */
 if (HAL_I2CEx_ConfigAnalogFilter(&hi2c2, I2C_ANALOGFILTER_ENABLE) != HAL_OK)
 {
 Error_Handler();
 }
 /** Configure Digital filter 
 */
 if (HAL_I2CEx_ConfigDigitalFilter(&hi2c2, 0) != HAL_OK)
 {
 Error_Handler();
 }
}

Here is my interrupt

void I2C2_EV_IRQHandler(void)
{
	 if (I2C2->ISR & 1<<1)
	 {
	 i2ccounter++;
	 I2C2->TXDR = DACdata[i2ccounter];
	 }
 
	 if (I2C2->ISR & 1<<6)
	 	 {
		 	 i2ccounter = 0;
	 	 I2C2 ->CR2 |= 1<<13;
	 	 }
 HAL_I2C_EV_IRQHandler(&hi2c2);
}

at the start of the main I use

 I2C2 ->CR2 |= 0b111 << 16; //bytes to send = 8
 I2C2 ->CR2 |= 1<<13; //start I2C

Can anyone tell me what im missing here?

[KnarfB]

Have you enabled the interrupt in the NVIC?

I wouldn't mix HAL and register level prog.

[deep_rune]

yes the I2C event interrupt is enabled in the NVIC

interesting about the mixture of HAL and register level programming - why avoid it? i usually use HAL only via cube, otherwise everything with the registers

[KnarfB]

You are starting the transfer with flipping a bit, not with HAL_I2C_Master_Transmit_IT.

This might be okay, but HAL_I2C_Master_Transmit_IT would have done more, perharps changing some values in hi2c2.

Later, when HAL_I2C_EV_IRQHandler is called, it uses hi2c2 which was not prepared accordingly.

IMHO doing the setup with HAL and the rest without HAL would be safer.

[KnarfB]

Did you set TXIE? Don't see code for I2C2 ->CR1.