7 Application Code

The code example updates the stored GPIO state any time a pin observes a rising or falling edge. The IRQ_OUT pin is only pulled low when an input pin observes a rising or falling edge, and is pulled high once the controller requests a read. The TX FIFO is filled upon receiving an I2C Start and is flushed upon an I2C Stop:

//I2C INT
void I2C_INST_IRQHandler(void)
{
    switch (DL_I2C_getPendingInterrupt(I2C_INST)) {
        case DL_I2C_IIDX_TARGET_START: 
            /* Fill TX FIFO with current pin state */
            DL_I2C_fillTargetTXFIFO(I2C_INST, &gGpioState, 1);
            break;
        case DL_I2C_IIDX_TARGET_RXFIFO_TRIGGER: 
            /* Store received data in buffer */
            while (DL_I2C_isTargetRXFIFOEmpty(I2C_INST) != true) {
                receivePacket(DL_I2C_receiveTargetData(I2C_INST)); 
            }
            break;
        case DL_I2C_IIDX_TARGET_TX_DONE: 
            /* Pull interrupt pin high when Controller reads from IO Expander */
            DL_GPIO_setPins(GPIO_GRP_0_PORT, GPIO_GRP_0_IRQ_OUT_PIN);
            break;
        case DL_I2C_IIDX_TARGET_STOP: 
            /* Flush TX FIFO */
            DL_I2C_flushTargetTXFIFO(I2C_INST);
            break;
        default:
            break; 
    }
}

void GPIOA_IRQHandler(void)
{ 
    /* Store the current pin state */
    gGpioState = (DL_GPIO_readPinStatus(GPIO_GRP_0_PIN_7_PIN) << 7) |
                 (DL_GPIO_readPinStatus(GPIO_GRP_0_PIN_6_PIN) << 6) | 
                 (DL_GPIO_readPinStatus(GPIO_GRP_0_PIN_5_PIN) << 5) | 
                 (DL_GPIO_readPinStatus(GPIO_GRP_0_PIN_4_PIN) << 4) | 
                 (DL_GPIO_readPinStatus(GPIO_GRP_0_PIN_3_PIN) << 3) | 
                 (DL_GPIO_readPinStatus(GPIO_GRP_0_PIN_2_PIN) << 2) | 
                 (DL_GPIO_readPinStatus(GPIO_GRP_0_PIN_1_PIN) << 1) | 
                 (DL_GPIO_readPinStatus(GPIO_GRP_0_PIN_0_PIN)); 

    /* Loop through all pins */
    for (int i = 0; i < 8; i++) { 
        /* Check if the current pin state changed */
        if (((gGpioState >> i) & 0x1) != ((gLastGpioState >> i) & 0x1)) { 
            /* If the pin is an Input */
            if (((gGpioDirection >> i) & 0x1) == 0) { 
                /* Pull interrupt pin LOW when an input pin state changes */
                DL_GPIO_clearPins(GPIO_GRP_0_PORT, GPIO_GRP_0_IRQ_OUT_PIN); 
            } 
        } 
    }
    gLastGpioState = gGpioState;
}

The controller IRQ_IN interrupt is triggered upon a detected falling edge, where a read to the IO expander is requested:

void GPIOA_IRQHandler(void)
{ 
    /* Set LED HIGH */
    DL_GPIO_clearPins(GROUP0_PORT, GROUP0_LED_PIN); 

    /* Request a read from the IO Expander */
    gRxLen = I2C_RX_PACKET_SIZE;
    gRxCount = 0; 

    /* Wait until the I2C bus is idle */
    while (!(DL_I2C_getControllerStatus(I2C_INST) & DL_I2C_CONTROLLER_STATUS_IDLE)); 

    /* Start a read operation */
    gI2cControllerStatus = I2C_STATUS_RX_STARTED;
    DL_I2C_startControllerTransfer(I2C_INST, I2C_IO_EXPANDER_ADDRESS,
                                    DL_I2C_CONTROLLER_DIRECTION_RX, gRxLen); 
    /* Enable RX FIFO trigger interrupt */
    DL_I2C_enableInterrupt(I2C_INST, DL_I2C_INTERRUPT_CONTROLLER_RXFIFO_TRIGGER);
}