FT810Q datasheet(34/60 Pages) FTDI

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Document No.: FT_001165

FT81X

Embedded Video Engine

Datasheet Version 1.2

Clearance No.:

FTDI#440

Figure 4-9 Touch screen connection

The host controls the CTSE operation mode by writing the REG_CTOUCH_MODE.

Table 4-18 Capacitive Touch Controller Operating Mode

REG_CTOUCH_MODE

Mode

Description

OFF

Acquisition stopped

1-2

Reserved

CONTINUOUS Perform acquisition continuously at the reporting rate of the

connected CTPM.

The FT81x CTSE supports compatibility mode and extended mode. By default the CTSE runs in

compatibility mode where the touch system provides an interface very similar to the resistive touch

engine. In this mode the same application code can run on FT810/FT812 and FT811/FT813 without

alteration. In extended mode, the touch register meanings are modified, and a second set of registers are

exposed. These allow multi-touch detection (up to 5 touches).

4.7.3 Compatibility mode

The CTSE reads the X and Y coordinates from the CTPM and writes to register REG_CTOUCH_RAW_XY. If

the touch screen is not being pressed, both registers read 65535 (FFFFh).

These touch values are transformed into screen coordinates using the matrix in registers

REG_CTOUCH_TRANSFORM_A-F.

The

post-transform

coordinates

are

available

REG_CTOUCH_SCREEN_XY. If the touch screen is not being pressed, both registers read -32768 (8000h).

The values for REG_CTOUCH_TRANSFORM_A-F may be computed using an on-screen calibration process.

If the screen is being touched, the screen coordinates are looked up in the screen's tag buffer, delivering

a final 8-bit tag value, in REG_TOUCH_TAG. Because the tag lookup takes a full frame, and touch

coordinates change continuously, the original (x; y) used for the tag lookup is also available in

REG_TOUCH_TAG_XY.

4.7.4 Extended mode

Setting REG_CTOUCH_EXTENDED to 1b’0 enables extended mode. In extended mode a new set of

readout registers are available, allowing gestures and up to five touches to be read. There are two

classes of registers: control registers and status registers. Control registers are written by the MCU.

Status registers can be read out by the MCU and the FT81x’s hardware tag system.

SCL

RSTN

SDA

INTN

FT811/

FT813

CTP_SCL

CTP_SDA

CTP_INT_N

CTP_RST_N

Capacitive Touch

Panel Module

VCCIO2

(1.8-3.3V)

FT810Q Datasheet(PDF) 34 Page - Future Technology Devices International Ltd.

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