8.5.1.2 Command and Response Protocol Layer
The host initiates every transaction between the host and the BQ79606A-Q1. The BQ79606A-Q1 never transmits data without first receiving a command frame from the host. After a command frame is transmitted, the initiator must wait for all expected responses to be returned (or a timeout in case of error) before initiating a new command frame. There are multiple types of commands:
- Single Device Read – This command is used to read a register(s) from a single device in the stack or base/bridge devices.
- Single Device Write – This command is used to write a register(s) to a single device in the stack or base/bridge devices.
- Stack Read – This command is used to read a register(s) from the stack devices only. The CONFIG[STACK_DEV] bit is used to configure a device as a stack device. The IC must be configured as a stack device (CONFIG[STACK_DEV] = 1) to respond to Stack Read commands.
- Stack Write – This command is used to write a register(s) for only the stack devices. The CONFIG[STACK_DEV] bit is used to configure a device as a stack device. The IC must be configured as a stack device (CONFIG[STACK_DEV] = 1) to respond to Stack Write commands.
- Broadcast Read – This command is used to read a register(s) for all of the devices in the stack (including base and bridge devices).
- Broadcast Write – This command is used to write a register(s) for all of the devices in the stack (including base and bridge devices).
- Broadcast Write Reverse Direction – This command is used to send a broadcast write in the reverse direction from the direction selected using the CONTROL1[DIR_SEL] bit. This command is intended to be used for switching the communication direction for the stack interface.
NOTE
A response frame is not mandatary as part of the protocol. A response frame is only received from a read command frame.