ZHCSTD7A December 2021 – November 2023 BQ79631-Q1
PRODUCTION DATA
Usually, device is expecting to receive communication based on the [DIR_SEL] setting. If a device receives communication frame opposite to the [DIR_SEL] setting, such as receiving command frame from COMH while [DIR_SEL] = 0, it will flag the communication as error. The broadcast write reverse direction is a command used to change flip the [DIR_SEL] setting when host needs to switch the daisy-chain communication direction. This command is expected to receive from an opposite direction than the [DIR_SEL] setting during reverse communication direction procedure. See Section 8.3.5.1.3.4 for details.
Although the broadcast write reverse direction is allowed to write any register value to the device, it is not recommended to write any other register setting other than the CONTROL1[DIR_SEL] to avoid communication collisions. Communication collisions are not detected and result in corrupted communication on the stack interface.
Broadcast Write Reverse Direction Command Sent by Host | ||
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Example | Set the [DIR_SEL] = 1 on All Devices in the Daisy-Chain | |
Frame Field | Data | Comments |
Initialization Byte | 0xE0 | Always 0xE0 FRAME_TYPE = 1 REQ_TYPE = 0b110 = Broadcast Write Reverse Direction DATA_SIZE = 0b000 |
Device Address | N/A | No need to include the device address byte in command frame |
Register Address | 0x0309 | Address of CONTROL1 register |
Data | 0x80 | Set CONTROL1[DIR_SEL] = 1 |
CRC | 0xC014 |