BT817AQ-R datasheet(32/58 Pages) BRIDGETEK

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BT817A Automotive Advanced Video Engine Datasheet

Version 1.0

Document No.: BRT_000251 Clearance No.: BRT#194

The mono audio formats supported are 8-bits PCM, 8-bits uLAW and 4-bits IMA-ADPCM.

For

ADPCM_SAMPLES, each sample is 4 bits, so two samples are packed per byte, the first sample is in

bits 0-3 and the second is in bits 4-7.

The current audio playback read pointer can be queried by reading the REG_PLAYBACK_READPTR.

Using a large sample buffer, looping, and this read pointer, the host MPU/MCU can supply a

continuous stream of audio.

4.8 Touch-Screen Engine

The BT817A touch-screen engine supports capacitive touch panels.

4.8.1 Capacitive Touch Control

The Capacitive Touch Screen Engine (CTSE) of the BT817A communicates with the external capacitive

touch panel module (CTPM) through an I2C interface. The CTPM will assert its interrupt line when

there is a touch detected. Upon detecting CTP_INT_N line active, the BT817A will read the touch data

through I2C. Up to 5 touches can be reported and stored in BT817 registers. The BT817 built-in ROM

code supports Focaltech, Hycontek and Goodix touch controllers, as well as touch host mode (refer to

section 4.8.5). For a supported CTPM list please refer to AN_336 FT8xx - Selecting an LCD Display. For

other touch controller IC, consult Bridgetek.

The BT817A uses the I2C address value in the REG_TOUCH_CONFIG register to differentiate

Focaltech/Hycontek and Goodix touch controllers. For Focaltech/Hycontek IC the I2C address must be

set as 0x38-0x3F (example: REG_TOUCH_CONFIG = 0x0380), while for Goodix IC the I2C address

must be set as 0x5D (example: REG_TOUCH_CONFIG = 0x05D0). The touch engine requires a reset if

changing I2C address from default value, as shown below:

Write REG_CPURESET = 2

Write REG_TOUCH_CONFIG = 0x05D0

//For Goodix touch controller

Write REG_CPURESET = 0

The BT817A supports I2C clock stretch. This is particularly useful for supporting Hycontek touch IC.

Figure 4-7 Touch Screen Connection

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

REG_CTOUCH_MODE Mode

Description

OFF

Acquisition stopped

1-2

Reserved

CONTINUOUS

Perform acquisition continuously at the reporting rate of the

connected CTPM.

Table 4-19 Capacitive Touch Controller Operating Mode

SCL

RSTN

SDA

INTN

BT817A

CTP_SCL

CTP_SDA

CTP_INT_N

CTP_RST_N

Capacitive Touch

Panel Module

VCCIO2

(1.8-3.3V)

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