Part Number: ADS7845 Tool/software: It is a 5-wire touch screen controller chip with a 12-bit ADC, interface over SPI For our application, we are trying to use it to read a certain 5-wire resistive touch screen. But for some reason, although we are trying to read the touch screen in single-ended mode, the values we read from the controller are garbage/random when someone touches the touch screen lightly. Garbage in this context means that it may deliver consistent values, which is bad because the microcontroller reading it might interpret that an honest touch is happening elsewhere on the touchscreen. And when someone does touch the touch screen with force, the range of values is severely truncated. Instead of a 0 to 4095 range, we see a 200 to 1400 range, which is a massive reduction. Is there a way to determine how hard someone is pressing down on the touchscreen from this driver? I wanted to know if maybe I was doing something wrong with the hardware design? What could cause this behavior? Is this a common problem?
↧