8.3.7.1 Kick-Back Voltage Measurement
TPS65185x can perform a voltage measurement on the VCOM pin to determine the kick-back voltage of the panel. This allows in-system calibration of VCOM. To perform a kick-back voltage measurement, follow these steps:
- Pull the WAKEUP pin and the PWRUP pin high to enable all output rails.
- Set the HiZ bit in the VCOM2 register. This puts the VCOM pin in a high-impedance state.
- Drive the panel with the Null waveform. Refer to E-Ink specification for detail.
- Set the ACQ bit in the VCOM2 register to 1. This starts the measurement routine.
- When the measurement is complete, the ACQC (Acquisition Complete) bit in the INT1 register is set and the nINT pin is pulled low.
- The measurement result is stored in the VCOM[8:0] bits of the VCOM1 and VCOM2 register.
The measurement result is not automatically programmed into nonvolatile memory. Changing the power-up default is described in the following paragraph.