ADS7843 PENIRQ no function

[PlsHelp]

Dear All,

I have facing the /PENIRQ problem. I did tried a lot of testing and changing the 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 there anyone can help me and give some advice?

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

Thank you,..