TAS3103ADBTR datasheet(61/152 Pages) TI

61 / 152 page

2−27

The watchdog timer is governed by the parameter GPIOFSCOUNT in subaddress 0xEF and the LSB of the 32-bit

word at subaddress 0xEB. The default value of the LSB of the 32-bit word at subaddress 0xEB is 1, and this value

disables the watchdog timer. The GPIOFSCOUNT is also used in other functions and balancing the needs of these

other functions regarding GPIOFSCOUNT with the requirements of the watchdog timer is an involved process. For

this reason, it is strongly recommended that the LSB of the 32-bit word at subaddress 0xEB remain a 1. If an

application does require use of the watchdog timer, it is requested that the user contact an application engineer in

the Digital Audio Department of Texas Instruments for details in properly using this feature.

2.8

General-Purpose I/O (GPIO) Ports

The TAS3103A has four general-purpose I/O (GPIO) ports. Figure 2−23 is a block diagram of the GPIO circuitry in

the TAS3103A.

GPIO0

GPIO1

GPIO2

GPIO3

Sample

Logic

0xEF

Down

Counter

LRCLK

Decode 0

DATA PATH SWITCH

GPIODIR

Determines How Many Consecutive Logic-0 Samples

(Where Each Sample Is Spaced by GPIOFSCOUNT

LRCLKs) are Required to Read a Logic 0 on a

GPIO Input Port

S Slave Addr

Subaddr

Ack

00000000

Ack

21 0

0000

Ack GPIOFSCOUNT Ack GPIO_samp_int Ack

23 20 19

Microprocessor

Firmware

Microprocessor

Control

0xEE

GPIO_in_out

S Slave Addr

Subaddr

Ack

00000000

Ack

21 0

Ack

00000000

00000000 Ack

0000

Ack

I2C Slave Mode

and

I2C Master Mode

Write

I2C Master

Mode Read

Figure 2−23. GPIO Port Circuitry

2.8.1

GPIO Functionality—I2C Master Mode

In the I2C master mode, the GPIO ports are strictly input ports and are used to control volume. Table 2−6 lists the

functionality of each GPIO port in the I2C master mode. Bit field GPIOFSCOUNT (15:8) of I2C subaddress 0xEF

governs the rate at which the GPIO pins are sampled for a volume update. The sample rate is:

GPIO_Port +

LRCLK

GPIOFSCOUNT

TAS3103ADBTR Datasheet(PDF) 61 Page - Texas Instruments

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