Sysclk LWLA1034/Protocol
Command messages sent to the device appear to be a sequence of 16-bit words with little endian byte order. The first word in a message identifies the command type. Different command types have different message lengths. Some command types include a length field and allow for messages of variable length, others are of fixed size.
There are read commands which trigger an immediate response from the device, and write commands without a response.
Command 0001: Read Register
This command appears to read a 32-bit wide control register.
Command
Fixed length of 2 words (4 bytes).
| ID | Address |
|---|---|
| 0001 | aaaa |
Response
The response has a fixed length of 4 bytes. It is likely the content of a 32-bit register in either little endian or mixed endian byte order.
Command 0002: Write Register
This command appears to write a 32-bit value to a control register.
Command
Fixed length of 4 words (8 bytes).
| ID | Address | Data |
|---|---|---|
| 0002 | aaaa | dddd-dddd |
The data is likely either in little endian or in mixed endian byte order.
Command 0005: Write ???
This command appears to write 16 32-bit words at once. It is issued once after a transfer of captured data to the host has finished.
Command
Fixed length of 33 words (66 bytes).
| ID | Data 1 | Data 2 | Data 3 | Data 4 | Data 5 | Data 6 | Data 7 | Data 8 | Data 9 | Data 10 | Data 11 | Data 12 | Data 13 | Data 14 | Data 15 | Data 16 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0005 | dddd-dddd | dddd-dddd | dddd-dddd | dddd-dddd | dddd-dddd | dddd-dddd | dddd-dddd | dddd-dddd | dddd-dddd | dddd-dddd | dddd-dddd | dddd-dddd | dddd-dddd | dddd-dddd | dddd-dddd | dddd-dddd |
The individual 32-bit words are likely either in little endian or in mixed endian byte order.
Command 0006: Read Memory at Address
This command appears to read a block from the device memory (probably the SRAM). It allows for random access using a 32-bit start address, and variable length via a 32-bit length field. The software uses this command to read captured data from the device's buffer.
Command
Fixed length of 5 words (10 bytes).
| ID | Address | Length |
|---|---|---|
| 0006 | aaaa-aaaa | nnnn-nnnn |
Both the address and the length are apparently encoded with mixed endian (2-1-4-3) byte order: MSW (16 bit) followed by LSW (16 bit), with the two bytes making up each individual 16-bit word in little endian order.
Response
The memory is apparently 36 bit wide: The size of the response in bits is 36 times the value in the length field. The software reads chunks of 120 words @ 36 bit at a time, which works out to an integer multiple of 8 (i.e. 4320 bits = 540 bytes).
Note that the software always starts reading at address 4 rather than 0. Presumably the firmware uses the first four 36-bit words for internal bookkeeping.