TLC6989 datasheet(32/72 Pages) TI1

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REG_RD (Register Read command)

Return to the SPI Command Table

The REG_RD command is used to read the internal registers of the TLC6989 device. The command includes a

field to indicate the address of the first register to be read. Even when the received CRC does not match with

the calculated CRC over the command word, the device returns the requested number of register words and

the CRC calculated over the register words. When the received CRC does not match the calculated CRC over

the command word, the FAULT pin is pulled low (when not masked) and the flag FLAG_SPI_CRC is set. An

example of REG_RD command reading 3 registers is depicted in Figure 7-21.

SDI

SDO

SOUT

0xD202

CRC0

CRC1

CCSIST

TXFFST

RXFFST

Figure 7-21. Example of REG_RD command

SOFTRESET_CRC (Softreset CRC command)

Return to the SPI Command Table

The SOFTRESET_CRC command is used to reset all internal registers to the default values and synchronize the

CCSI controller and peripheral. The command is executed when:

• The received CRC matches with the calculated CRC over the command word, and

• The CCSI controller is not transmitting

The CRC value for the SOFTRESET_CRC command using CCITT-FALSE algorithm is 0xD383 and when using

CRC-16/XMODEM algorithm 0xCE8C.

With a reset of all the internal registers, most of the fault flags that were previously set, are cleared.

Only FLAG_POR and FLAG_ERR are reset to HIGH. In addition, all data stored on the RXFIFO becomes

inaccessible. If there are CCSI commands in the LED daisy chain that have not been received yet by the

CCSI peripheral, the CCSI CRC diagnostics cannot be checked anymore because the calculated CRC values

have been cleared for the purpose of synchronization between the CCSI controller and CCSI peripheral. TI

recommends to transmit the same number of END bytes as the number of LED drivers in the daisy chain

after transmitting the SOFTRESET_CRC command. This clears any already transmitted CCSI command and

therefore keeps the synchronization. When the device is in FAILSAFE mode, the SOFTRESET_CRC command

brings the device to NORMAL mode. An unsuccessful SOFTRESET_CRC command is recorded in the bit

FLAG_SRST in the STATUS register. An example of SOFTRESET_CRC command is depicted in Figure 7-22.

SDI

SDO

SOUT

0xE1E1

CRC0

STATUS

CRC1

Figure 7-22. Example of SOFTRESET_CRC command

TLC6989

SLVSHF5 – NOVEMBER 2024

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TLC6989 Datasheet(PDF) 32 Page - Texas Instruments

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