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LeddarVu User Guide Page 46 of 129
Table 13: Basic modes
Mode
Clock Polarity
CPOL
Clock Phase
CPHA
0
0
0
1
0
1
2
1
0
3
1
1
5.1.2. SPI Protocol
The universal SPI protocol uses a combination of standard commands for FLASH and SRAM
memories.
Each SPI packet contains a header, a payload, and a cyclic redundancy check (CRC).
The first byte of the header corresponds to an instruction opcode. It is followed by a 24-bit address
and the 16-bit size of the payload. The payload contains several user-data bytes. The last 16 bits
of the packet is the CRC16 (IBM) of both header and payload. The table below summarizes the
structure of an SPI packet. It is noted that address and the CRC are packed with the most significant
byte first while the first byte of data corresponds to the least significant byte.
Table 14: Byte offsets
Field
Opcode
Address
Data
CRC16
Byte
offset
1
2
3
4
5
6
7
7 + n
8 + n
9 + n