ADS7843 PENIRQ no function

[Help]

Dear All,

I have facing the /PENIRQ problem. I did tried a lot of testing and changing a few ADS7843 and TFT-touch-screen but still no working.

I would like to compare the result with you all.

1) I'm using 3.2" screen. I did measure the touch screen resistance for the X-,X+ is ~300Ohm and Y-,Y+ is ~400Ohm. (without connecting to ADS7843 device)
2) Connect touch screen pin X-,X+,Y-,Y+ to ADS7843 and measure the voltage at point X-,X+,Y-,Y+. (ADS7843 operate at 3.3V and /PENIRQ external pull up 100K Ohm)

No touch on screen:
X+ = 2.315V
Y+ = 2.315V
X- = 0.000V
Y- = 0.000V
/PENIRQ = 3.3V

Touch on screen:
X+ = 2.315V
Y+ = 2.315V
X- = 2.315V
Y- = 2.315V
/PENIRQ = 3.3V

I wonder why the /PENIRQ wouldn't pull to low as per datasheet said once the /PENIRQ is pulled LOW, a voltage typically will not exceeding 0.65V.

Is it we need to initialize the ADS7843 using coding before we can use the PENIRQ?

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Code ASM - [expand]
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void GetScrXY(int *x, int *y)  
    {
    unsigned char msb, lsb;
 
// Get X coordinate     
    CS = 0;
    dly(6); 
    
    spi_write(0xD0);
    
    dly(80); // BUSY
    
    msb= spi_write(0x00); // msb
    lsb = spi_write(0x00); // lsb
    
    CS = 1;
 
    *x = (msb*0x100) | lsb;
 
    dly(100); 
 
// Get Y coordinate      
    CS = 0;
    dly(6); 
        
    spi_write(0x90);
 
    dly(80); // BUSY
    
    msb= spi_write(0x00); // msb
    lsb = spi_write(0x00); // lsb
    
    CS = 1;
 
    *y = (msb*0x100) | lsb;
 
    }
 
void Check_PENIRQ(void)
    {
    int x,y;
    
    GetScrXY(&x, &y) ;
 
    if(PENIRQ)
        LED = 0;
    else
        LED = 1; 
    }

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Above coding is what i trying to use a LED to capture the PENIRQ pin.

Is there anyone can help me and give some advice?

Thank you,..