AN1250 datasheet(5/22 Pages) MICROCHIP

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DS01250A-page 5

AN1250

EXAMPLE 2:

CTMU AND A/D CONVERTER SETUP FOR PIC18F

In the case of the PIDEM Touch Sense 2 Demo Board,

all 16 A/D channels are used for capacitive touch. Read-

ing of each of the sensor channels (A/D channels) is

controlled by Timer1. Timer1 is setup to fire at a 1 ms

interval. Each time that the Timer1 interrupt handler

runs, it increments the channel number of the A/D and

the capacitive sensor connected to that channel is read.

After all 16 touch sensors have been read, the Timer1

interrupt handler sets a flag called, “dataReadyCTMU”,

and the main routine uses this flag to know when to

process the new data just gathered from all 16 capacitive

touch sensors.

//setup CTMU

//CTMUCON

CTMUCONHbits.CTMUEN = 0;

//make sure CTMU is disabled

CTMUCONHbits.CTMUSIDL = 0;

//CTMU continues to run in idle mode

CTMUCONHbits.TGEN = 0;

//disable edge delay generation mode of the CTMU

CTMUCONHbits.EDGEN = 0;

//edges are blocked

CTMUCONHbits.EDGSEQEN = 0;

//edge sequence not needed

CTMUCONHbits.IDISSEN = 0;

//Do not ground the current source

CTMUCONHbits.CTTRIG = 0;

//Trigger Output is disabled

CTMUCONLbits.EDG2POL = 0;

CTMUCONLbits.EDG2SEL = 0x0;

//Edge2 Src = ECCP2 (don’t care)

CTMUCONLbits.EDG1POL = 1;

CTMUCONLbits.EDG1SEL = 0x1;

//Edge1 Src = ECCP1 pin (don’t care)

//CTMUICON

CTMUICON = 0x03;

//55uA

CTMUICON.ITRIM = 0;

//Nominal - No Adjustment

//setup A/D converter

ANCON0bits.PCFG = 0x00;

ANCON1 = 0x0000;

ADCON0bits.CHS = 0x00;

//select the analog channel 0

ADCON1bits.ADFM = 0x00;

//right justified result

ADCON1bits.ADON = 1;

//Turn On A/D

CTMUCONHbits.CTMUEN = 1;

//Enable CTMU

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