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APPENDIX A
Camera Control using the J* Command Protocol Interface
The serial protocol in use for the ProCam UHD is called the J* Protocol. The data format is
The serial protocol in use for the 4K Camera Module is called the J* Protocol. The data format is
38,400 baudrate, 8-bit, no parity with one stop bit. The packet consists of eight bytes, comprised
of two "Ident" bytes, five "Data" bytes, and one "Error" byte. The "Ident" byte depends on if the
data is being sent to the camera or if it is coming from the camera, as shown below:
The overall eight byte J* structure is shown below:
Byte 1
Byte 2
Ident 1
Ident 2
'*'
'J' or 'C'
When the data is being sent to the camera, use the following for the Ident bytes:
Ident byte 1
Ident byte 2
When data is being sent by the camera, it will use the following Ident bytes:
Ident byte 1
Ident byte 2
ERROR is calculated as the bitwise inverse of the lowbyte of the sum of
Data 1 + Data 2 + Data 3 + Data 4 + Data 5.
So if N = Data 1 + Data 2 + Data 3 + Data 4 + Data 5, then ERROR is the low byte of the XOR
of N.
The full command set is given in the next section, which includes the command index and value.
INDEX is used for 8-bit or16-bit values. SUBINDEX is used only for 8-bit values. Two commands
can be sent simultaneously by using INDEX and SUBINDEX. If the same command index is
used in both INDEX and SUBINDEX, the value used with SUBINDEX (Data 5 in Byte 7) will be
given priority over the value used with INDEX (Data 3 in Byte 5) The command packet can be
sent to the camera every 20 milliseconds and the commands will be received.
.
CAUTIONS:
Please wait for at least 20ms to send or receive each command.
Commands other than the J* Command Set (refer to page 24) will be out of operating
warranty.
Byte 3
Byte 4
Data 1
Data 2
INDEX
Data Hi
ASCII 'J'
Hex '4A'
ASCII '*'
Hex '2A'
ASCII 'C'
Hex '43'
ASCII '*'
Hex '2A'
Byte 5
Byte 6
Data 3
Data 4
Data Lo
SUBINDEX
20
19
23
Byte 7
Byte 8
Data 5
Error 1
Data
ERROR
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