Hawk Instruction Manual
Document number
Revision
File name
Date
Page
2015-07-22-05
V1.1
HK82x_IM_v1_1
30
th
Jul 2015
10 of 14
4 SERIAL COMMUNICATION (RS485)
4.1
Overview
For version 2.7 of the Micro firmware, the Power on default settings for camera serial port are;
-
115200 baud
-
1 start bit
-
8 data bits
-
1 stop bit
UART message format from Host to camera
Command
Data 1
Data 2
........
Data n
ETX
Chk_Sum
The first Byte is the command to the Microcontroller in the camera, following bytes contain data required by the
command, and the ETX byte terminates the command. 0x50 is always used to terminate the command. An
additional check sum byte may also be required to be sent by the host if check sum mode is enabled.
UART message format from camera to Host
Data 1
Data 2
........
Data n
ETX
Chk_Sum
All or none of the above bytes may be sent in response to commands from the host depending on the commands
sent by the host.
An optional mode of operation is included in the firmware for command acknowledge. Once enabled the camera
will respond to all commands send by the host. After the camera has received and processed the command from
the host, a single command acknowledge byte will be sent at the end of transmission (ETX) i.e. should the host
command require data to be sent from the camera then the ETX byte will be sent at the end of the requested
data.
Another optional mode of operation is included in the firmware is for check sum operation, this mode should only
be used when the command acknowledge mode is enabled. Once the check sum mode is enabled the camera
will only act upon commands that are received with the correct check sum byte sent at the end of the command
packet. Note that if the check sum feature is not enabled check sum bytes may still be sent at the end of a
command packet, the command will be processed and the check sum will be ignored. The check sum byte should
be the result of the Exclusive OR of all bytes in the Host command packet including the ETX byte.
When check sum mode is enabled data returned from the camera will include an echo of the checksum from the
host command
By default the camera will boot up with both command acknowledge and check sum operation disabled.
It is intended that the camera be operated from a higher level perspective whereby complete UART messages or
groups of UART messages are used to achieve required camera functionality.
Bits in registers that have not been identified in the documentation should be ignored.
Once a command has been received by the camera all sub sequent commands from the host will be ignored until
the command has been processed.
