ADC On Interrupt LPC1788

[lpcware]

Content originally posted in LPCWare by amlwwalker on Mon Dec 16 12:42:52 MST 2013
Hi
I am trying to get my ADC's for my touchscreen working on an interrupt. They worked when I was polling the channels, but I dont get anything on an interrupt.

My setup code for the two channels is:

void prepareTouchScreen() {
ADC_Init(LPC_ADC, 400000);
/* Configure X1: */LPC_IOCON ->P0_24 = PIN_GPIO; /* X1 is a GPIO pin */
LPC_GPIO0 ->DIR |= (1 << 24); /* it's output */
LPC_GPIO0 ->SET = (1 << 24); /* and is set high */

/* Configure Y1: */LPC_IOCON ->P0_23 = PIN_GPIO; /* Y1 is a GPIO pin */
LPC_GPIO0 ->DIR |= (1 << 23); /* it's output */
LPC_GPIO0 ->SET = (1 << 23); /* and is set high */

/* Configure X2: */LPC_IOCON ->P0_22 = PIN_OD; /* simulated open drain (high impedance) mode */
LPC_GPIO0 ->DIR |= (1 << 22); /* this pin is always output */
LPC_GPIO0 ->SET = (1 << 22); /* and is set high (not sinking current) */

/* Configure Y2: */LPC_IOCON ->P0_21 = PIN_OD; /* simulated open drain (high impedance) mode */
LPC_GPIO0 ->DIR |= (1 << 21); /* this pin is always output */
LPC_GPIO0 ->SET = (1 << 21); /* and is set high (not sinking current) */
LOG("Touch Screen Prepared");
}

My code to read a channel is:

inline uint16_t startTouchscreenADC(uint8_t aDirection) {
LOG(__PRETTY_FUNCTION__);

/* Prepare pins: */
if (aDirection) {
LPC_IOCON ->P0_24 = PIN_ADC; /* X1 = ADC */
LPC_IOCON ->P0_23 = PIN_GPIO; /* Y1 = GPIO pin */
LPC_GPIO0 ->CLR = (1 << 22); /* set X2 low (now sinking current) */
LPC_GPIO0 ->SET = (1 << 21); /* set Y2 high (now high impedance) */
LOG("direction = 1");
} else {
LPC_IOCON ->P0_24 = PIN_GPIO; /* X1 = GPIO pin */
LPC_IOCON ->P0_23 = PIN_ADC; /* Y1 = ADC */
LPC_GPIO0 ->SET = (1 << 22); /* set X2 high (now high impedance) */
LPC_GPIO0 ->CLR = (1 << 21); /* set Y2 low (now sinking current) */
LOG("direction = 0");
}
ADC_ChannelCmd(LPC_ADC, 1 - aDirection, DISABLE);
ADC_ChannelCmd(LPC_ADC, aDirection, ENABLE);
LOG("direction changed");
LPC_ADC ->INTEN = (LPC_ADC ->INTEN & ~0x03) | (1 << aDirection); /* enable interrupt for this direction */
LPC_ADC->CR = ADC_CR_START_MODE_SEL(ADC_CR_START_NOW) | ADC_CR_PDN | ADC_CR_CH_SEL(aDirection);
LOG("finished conversion");

      return (ADC_DR_RESULT(LPC_ADC->DR[aDirection]));
}

In main I am doing:

        prepareTouchScreen();
        /* preemption = 1, sub-priority = 1 */
        NVIC_SetPriority(ADC_IRQn, ((0x01<<3)|0x01));
        LPC_ADC->INTEN = 0;                                             /* disable ADC interrupts */
        NVIC_ClearPendingIRQ(ADC_IRQn);                 /* clear ADC_IRQ pending bit in the NVIC */
        NVIC_EnableIRQ(ADC_IRQn);                               /* enable ADC_IRQ in the NVIC */
        startTouchscreenADC(0);
while(1){
}

Finally my ADC handler is:

void ADC_IRQHandler(void)
{
        static uint8_t  valid = 0;
        static uint16_t valueX = 0x8000;
        static uint16_t valueY = 0x8000;
        uint16_t                value;

        NVIC_ClearPendingIRQ(ADC_IRQn);

        // the static local variables above are for temporary values, until we have both values as a complete set.

        // read ADC values and store into appropriate variables:
        // get ADC channel status for channel 0, if it's ready

        LOG("Handler accessed");
       if(value & ADC_DR_DONE_FLAG)                            // this might happen right now, it might not
        {
               valueX = ADC_DR_RESULT(value);                  // store value temporarily
                valid |= X_VALID;                                               // X position is now valid
                startTouchscreenADC(1);                                 // start conversion for channel 1.
        }
        // get ADC channel status for channel 1, if it's ready
       value = LPC_ADC->DR[1];
       if(value & ADC_DR_DONE_FLAG)                            // this might happen right now, it might not
        {
               valueY = ADC_DR_RESULT(value);                  // store value temporarily
                valid |= Y_VALID;                                               // Y position is now valid
                startTouchscreenADC(0);                                 // start conversion for channel 0.
        }
        if(BOTH_VALID == valid)
        {
                valid = 0;

                if(valueX >= TOUCH_X_MIN && valueX < TOUCH_X_MAX && valueY >= TOUCH_Y_MIN && valueY < TOUCH_Y_MAX)
                {
                        touchPos = (valueX << 16) | (valueY & 0xffff);
                        touchState = 1;
                }
                else
                {
                        touchState = 0;                                         // not touched.
                        touchPos = 0x80008000;                          // coordinates somewhere far away. :)
                }
        }
}

I am expecting to see:

LOG("Handler accessed");

If I touch the touchscreen and the Handler is called.
What I do see is on my terminal is:

---

Quote:

Touch Screen Prepared

startTouchscreenADC

direction = 0

direction changed

finished conversion

---

Can anyone see why Im not getting anything back when I touch the touchscreen? Im not sure why its not going into the handler. Im trying to setup JTAG debugging now to see if I can get anything but any help would be greatly appreciated.

Alex

[lpcware]

Content originally posted in LPCWare by amlwwalker on Tue Dec 17 14:15:45 MST 2013
no one can help me?
I thought this kind of thing would be straight forward, but its turning out not to be...there is very little on this and the example is correct.