ZHCSTD7A December 2021 – November 2023 BQ79631-Q1
PRODUCTION DATA
The daisy-chain communication for the device uses a Ring architecture. In this architecture, a cable break between two devices does not prevent communication to all upstream devices as in a normal non-Ring scheme. When the host detects a broken communication, the device allows the host to switch the communication direction to communicate with devices on both sides of the break. This allows for safe operation until the break in the lines is repaired.
The CONTROL1[DIR_SEL] controls the communication direction. The devices will reconfigure the COMH and COML ports depending on the [DIR_SEL] and the [TOP_STACK] settings. Auto-addressing procedure is needed to re-address the device address for the reverse communication direction.
Example to change the communication direction to [DIR_SEL] = 1 to the entire daisy-chain:
Once the device address in both communication directions is set up, host can skip auto-address step when switching communication direction.
In a broken cable case, host follows the same procedure to change the communication direction. To access all devices in the daisy-chain, host will have to communicate with [DIR_SEL] = 0 on some devices and communicate with [DIR_SEL] = 1 on other devices in the daisy-chain. The chain will also have two ToS devices, one for each communication direction.