ZHCSJM7 April 2019 BQ79606A-Q1
PRODUCTION DATA.
The Frame Initialization Byte is used in both Command and Response Frames. It is always the first byte of the frame. The Frame Initialization Bytes performs two functions. First, it defines the frame as either a Command Frame (host) or a Response Frame (slave). Second, it defines the length of the frame that follows after the Frame Initialization Byte. This provides the receiver an exact number of bytes to expect for a complete command/response. If the transmission does not complete the correct number of bytes before the timeout occurs, an communication time out is generated if enabled. The Frame Initialization Byte for both the Command and Response frame is defined in Table 8.
| Bit | Name | Description |
|---|---|---|
| 7 | Frame_Type | 1: Defines Command Frame |
| 6 | REQ_TYPE | 000: Single Device Read
001: Single Device Write 010: Stack Read 011: Stack Write 100: Broadcast Read 101: Broadcast Write 110: Broadcast Write Reverse Direction (use when changing the daisy chain communication direction) 111: Reserved. Any writes with this bit selection perform no function and sets COMM_COML_RC_FAULT[IERR], COMM_COMH_RC_FAULT[IERR], COMM_UART_RC_FAULT[IERR] (depending on which interface receives the fault). |
| 5 | ||
| 4 | ||
| 3 | Reserved | Reserved. Any write received to this bit is ignored. |
| 2 | DATA_SIZE | Number of bytes of data to be sent, not including the device address, register address, or CRC byte(s)
000: 1 bytes 001: 2 byte 010: 3 bytes 011: 4 bytes 100: 5 bytes 101: 6 bytes 110: 7 bytes 111: 8 bytes |
| 1 | ||
| 0 |
| Bit | Name | Description |
|---|---|---|
| 7 | Frame_Type | 0: Defines Response Frame |
| 6 | RESPONSE_BYTES | 0b0000000 - 0b1111111: Defines the number of data bytes contained in the response frame minus 1. For example, if 6 bytes are contained in the response frame, the RESPONSE_BYTES = 0b0000101 |
| 5 | ||
| 4 | ||
| 3 | ||
| 2 | ||
| 1 | ||
| 0 |