This document provides details on the advanced features of the S-Touch® STMPE811 touchscreen controllers, including autonomous operation, FIFO memory, movement tracking, averaging data to optimize noise cancellation, and window tracking.
This document describes the advanced features of the STMPE811 resistive touchscreen controller, including autonomous operation, a 128-depth FIFO buffer, movement tracking algorithms, and window tracking capabilities designed to reduce host load.
The note provides descriptions for various controller settings such as ADC sample time, bit mode, clock frequency, and operating modes. It also includes basic guidelines on using touch detect and FIFO interrupts effectively.
| FIFO depth | 128 sectors |
|---|---|
| ADC resolution options | 10 and 12 bits |
| Recommended ADC clock frequency | 3.25 MHz |
| Touch detect pull-up resistor | 50 kΩ |
| Tracking index options | 0, 4, 8, 16, 32, 64, 92 and 127 |
The recommended setting is 80 clock cycles as a compromise between speed and accuracy.
The 12-bit resolution is recommended for bigger screen applications to achieve sufficient touch resolution.
1-5 nF capacitors require around 500 µs settling time.