TOUCH SLIDER

[complex72]

Hi I've been doing some work using the TOUCHPAD functions for 3 buttons and a slider, Ive got the buttons to work perfect but how can I get the slider (2 inverse triangles) to work with this functions? I've read the AN1250 pdf provided by microchip and they actually give a formula on how to calculate the position, but is there a way to do this with the compiler? thank you

#USE TOUCHPAD (RANGE=H,THRESHOLD=3,SCANTIME=32,PIN_B0='1',PIN_B1='2',PIN_B2='3')


void main(void)
{

char c;
enable_interrupts(GLOBAL);



while (TRUE)
{


if ( TOUCHPAD_HIT() )
c = TOUCHPAD_GETC(); //gets wich cap button was toched

switch ('c')
{
case '1':
output_high(pin_c0);
output_high(pin_a5);
output_low(pin_c3);
break;

case '2':
output_low(pin_c0);
output_high(pin_a5);
output_low(pin_c3);
break;

case '3':
output_low(pin_c0);
output_low(pin_a5);
output_high(pin_c3);
break;

}


}

}

[Ttelmah]

Yes.

The key is to use the touchpad_state function, not the getc.

touchpad_state(1);

stores the values from the connected pads as int16 numbers directly into the array 'TOUCHDATA'. It's defined to have the size for the number of pins you use. Then TOUCHDATA[0] is the actual direct reading from the first pad etc..

You ignore the threshold etc., and just look at the values from the two pads you use for the slider, One will go up, and the other down, as the finger moves along the slider.

Add the pins you are using for the slider to your touchpad setup, giving them 'dummy' return values. Write your function that reads the keypad getc, to ignore these dummy values, and just read the numbers directly from the array, when they are seen (signal is above threshold).

Best Wishes

[complex72]

[complex72]

Does someone know about this topic that could help me out? thank you

[Ttelmah]

I 'played' with this quite a few versions ago, so things might well be different....

I defined the array to have the same number of entries as the number of pins supported by the CTMU, and the order in the array seemed to correspond to the ADC channel numbers.

I did a calibration pass before starting (touchpad_state(1)), delayed, and then tested 'if (touchpad_hit())', to tell if any pin was above it's threshold. Once I saw one was I triggered the touchpad_state(2), waited for long enough to ensure this had triggered, and read the array.

I actually had to give up on using the functions, because though they worked on another chip, they were not working correctly on the chip I wanted to use, so I went 'diy' on the functions. This was though quite a few compiler versions ago!...

Key was though that things didn't happen immediately. If you triggered the touchpad_state(2) function, you had to wait for the timer interrupt to trigger before things updated.

[complex72]

[complex72]

I talked with CCSC technical support and got the answer, the TOUCHDATA array isn't working because it doesn't exist, they found the issue and are going to fix it in the next version of the compiler, the real name of the array is in fact CTMU_THRESHOLD.
The data for each touch pin is stored in the array as two bytes, the index of the array that the touch pin data is stored in is based on which analog pin it is. For example if your using pin B0 as a touch pin, which is AN12 (PIC18F46K22) the least significant byte is in CTMU_THRESHOLD[24] and the most significant byte is in CTMU_THRESHOLD[25]. As an example you could use the next table:

-----------------------------------------
-----------LSB MSB
AN0-------0-----1
AN1-------2-----3
AN2-------4-----5
AN3-------6-----7
AN4-------8-----9
AN5------10----11
.
.
.
.
.
AN12-----24----25
--------------------------------------------

you could then take both bytes and do a make16 to get the real value.

Thanks alot Ttelmah and CCS support staff for your replies.!

[complex72]