Tuesday, February 18, 2014

Getting an Azoteq IQS213 IC touch IC to work with a Nordic Semiconductor nRF51822 microcontroller

I'm trying to get an Azoteq IQS213 touch controller to work with the Nordic Semiconductor NRF51822 processor in my smartwatch project.

According to the IQS213 documentation, the ready / TO2 line is supposed to go low after startup to signal that the IQS is ready to receive commands from the controller.

However, this is not happening. The TO2 line is supposed to have a 4.7 kOhm pull-up resistor. Instead I have used the processor's internal 11-16 kOhm resistor as pull-up. Since it's larger than the specified resistor, it should not prevent the line from going low.

I've verified:

  • Power (2.8V)
  • Ground
  • VReg (1.68 V)
  • Checked for shorts
  • Orientation of chip
Still no ready low.

Next step will be to look for anomaly notes from Azoteq, and program an ACK handshake to see if that could work.