Data Sheet

Copyright © Bridgetek Pte Ltd 37
BT81X (815/6) Advanced Embedded Video Engine Datasheet
Version 1.0
Document No.: BRT_000220 Clearance No.: BRT#126
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 0.
The host can use three methods to ensure that BT815 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 BT815 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 BT815 touch engine must be reset.
4.8.8 Touch Detection in none-ACTIVE State
When the BT815/6 is in none-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 BT816 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 BT815 is in STANDBY, SLEEP or
POWERDOWN state.
4.9 Power Management
4.9.1 Power Supply
The BT815/6 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
VCCIO3
1.8V, or 2.5V, or 3.3V
Supply for NOR Flash interface I/O pins
VCCA
3.3V
Supply for AUDIO_L pin and ADC circuit
VCC
3.3V
Supply for 3.3V circuits and internal 1.2V regulator
VOUT1V2,
VCC1V2
1.2V
Supply for digital core. Generated by internal regulator
Table 4-20 Power Supply