BT818Q-R datasheet(36/59 Pages) BRIDGETEK

36 / 59 page

BT817/8 Advanced Embedded Video Engine Datasheet

Version 1.1

Document No.: BRT_000302 Clearance No.: BRT#154

the host writes 0xf to the ID register, BT817 sets the ACK register to 0, transforms all the raw

coordinates, and writes the results to the regular touch registers.

Pseudocode:

wait until REG_EHOST_TOUCH_ACK is 1

for each touch:

write x coordinate to REG_EHOST_TOUCH_X

write y coordinate to REG_EHOST_TOUCH_Y

write id to REG_EHOST_TOUCH_ID

write 0xf to REG_EHOST_TOUCH_ID

As soon as BT817 has converted the coordinates, it writes 1 to the ACK register and sets the

INT_CONV_COMPLETE interrupt flag.

The ID should be zero in touch compatibility mode. The host should indicate no touch at all by writing

(0x8000; 0x8000) with ID 0.

In extended mode, the multiple touches may be sent in any order. Any IDs not assigned are assumed

to be not pressed. Again, the host should indicate no touch at all by writing (0x8000; 0x8000) with ID

The host can use three methods to ensure that BT817 is ready to accept touch inputs:

1. poll the ACK register until it is 1

2. use the INT_CONV_COMPLETE interrupt flag

3. supply touches slower than 1000 Hz, since BT817 guarantees to process the touches

in under 1 ms. Note that report rates from capacitive touch panels are about 100 Hz

Like the direct capacitive driver, this touch host mode works when REG_CTOUCH_EXTENDED is both

CTOUCH_MODE_EXTENDED and CTOUCH_MODE_COMPATIBILITY. CTOUCH_MODE_COMPATIBILITY

should be used for the calibration procedure, just as when using native capacitive support. After

changing mode, the BT817 touch engine must be reset.

4.8.8

Touch Detection in none-ACTIVE State

When the BT817/8 is in non-ACTIVE state, a touch event can still be detected and reported to the host

through the INT_N pin. In other words, a touch event can wake-up the host if needed.

For resistive touch, the INT_N pin will be asserted low when the screen is touched, regardless of the

setting of the interrupt registers. This will happen when the BT818 is in STANDBY or SLEEP state, but

not in POWERDOWN state.

For capacitive touch, the INT_N pin will follow CTP_INT_N pin when the BT817 is in STANDBY, SLEEP

or POWERDOWN state.

4.9 Power Management

4.9.1

Power Supply

The BT817/8 may be operated with a single supply of 3.3V applied to VCC and VCCIO pins. For

operation with a host MPU/MCU at a lower supply, connect the VCCIO1 to the MPU IO supply to match

the interface voltage. For operation with LCD/touch panels at lower voltages, connect the VCCIO2 to

the LCD/touch IO supply.

Symbol

Typical

Description

VCCIO1

1.8V, or 2.5V, or

3.3V

Supply for Host interface digital I/O pins

VCCIO2

1.8V, or 2.5V, or

3.3V

Supply for RGB and touch interface I/O pins

BT818Q-R Scheda tecnica(PDF) 36 Page - Bridgetek Pte Ltd.

BT818Q-R Scheda tecnica(HTML) 36 Page - Bridgetek Pte Ltd.

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59

Scheda tecnica Scarica

Link URL