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.