Datasheet

STMPE811 Touchscreen controller
Doc ID 14489 Rev 6 35/65
Sampling time calculation
The equation for a complete sampling cycle is described below.
Figure 12. Sampling time calculation
Oversampling and averaging function
The STMPE811 touchscreen controller can be configured to oversample by 2/4/8 times and
provide the averaged value as final output. This feature helps to reduce the effect of
surrounding noise.
Table 15. Touchscreen controller register summary table
Address Register name Bit Type Function
0x40 TSC_CTRL 8 R/W 4-wire touchscreen controller setup
0x41 TSC_CFG 8 R/W TSC configuration register
0x42 WDW_TR_X 16 R/W Window setup for top right X
0x44 WDW_TR_Y 16 R/W Window setup for top right Y
0x46 WDW_TR_X 16 R/W Window setup for bottom left X
0x48 WDW_TR_Y 16 R/W Window setup for bottom left Y
0x4A FIFO_TH 8 R/W FIFO level to generate interrupt
0x4B FIFO_STA 8 R/W Current status of FIFO
0x4C FIFO_SIZE 8 R Current filled level of FIFO
0x4D TSC_DATA_X 16 R Data port for TSC data access
0x4F TSC_DATA_Y 16 R Data port for TSC data access
AM08681V3
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A complete sampling cycle
To uch Detect Delay
Settling Time
Sampling X
Settling Time
Sampling Y
Settling Time
Sampling Z
To uch Detect Delay
Time taken for sampling;
- Touch Detect Delay x 2 + Settling Time x 3 + (AVE_CTRL x ADC_SAMPLE_TIME) x 3 for X/Y/Z mode
- Touch Detect Delay x 2 + Settling Time x 2 + (AVE_CTRL x ADC_SAMPLE_TIME) x 2 for X/Y mode