ZHCSTD7A December 2021 – November 2023 BQ79631-Q1
PRODUCTION DATA
During normal operation, host puts the device in SHUTDOWN mode through communication by sending CONTROL1[GOTO_SHUTDOWN] = 1. In a daisy-chain configuration, using broadcast write to send this command will put all devices in the daisy-chain in SHUTDOWN mode.
The device can also enter SHUTDOWN mode by one of the following conditions:
When a device is shutting down through SHUTDOWN or HW_RESET ping/tone, upon device wake-up, the FAULT_SYS[SHUTDOWN_REC] bit is set to indicate the previous shutdown is abnormal. For the base device, when device wakes up with [SHUTDOWN_REC] = 1, the COMH and COML ports are disabled thus isolating the base device from the daisy-chain to help checking on any communication issue. Once the host confirms the communication to the base device is good, host can issue a WAKE ping to reset the entire daisy-chain, which will clear the [SHUTDOWN_REC] bit as well as put the COMH/L ports of the base device back to their normal condition.
If [SHUTDOWN_REC] = 1 is on any of the stack devices, the COML and COMH will not be disabled upon device wake-up as the COMH/L ports are the only way to communicate to a stack device.