best way that i can read ttp223 events on mcp8574 ports

Using Arduino General Electronics
1

Hi
I have a pcf8574 and a ttp223 touch module, the min voltage that pcf8574 can read on I/O pins as an input is 5v(after my tests), and max output voltage on I/O pin of ttp223 is 3.7v,
What is the best way that i can read touch events on mcp8574 ports ?

2

According to the PCF8574 datasheet, table 6.3, a voltage greater than 0.7 * Vcc will be recognized as a HIGH. That is 3.5V on a 5V system so the 3.7V from the touch screen should register.

3

groundFungus:
According to the PCF8574 datasheet, table 6.3, a voltage greater than 0.7 * Vcc will be recognized as a HIGH. That is 3.5V on a 5V system so the 3.7V from the touch screen should register.

Yes, thanks, but not work with this voltage in my case !
The big question is how can i add a little down voltage to original voltage of touch I/o pin ?

4

odd situation is happened for me !! when i connect i/o pin of ttp223 to p0 of pcf8574, the ttp223 led gone low and the its output voltage gone to 1.5 v .
I have problem by connection i/o pin of ttp223 to pcf8574 input pins,
Why !? what is my problem ?!