I've been probing this CCTV DVR board trying to find a serial port to see if I can get console access to it. I found a set of 4 through holes with no headers that looked like a good candidate. I hooked up to my Bus Pirate in UART mode at a baud rate of 115200 and it seemed promising at first:
System startup
U-Boot 2010.06 (Dec 27 2018 - 17:06:41)
Check Flash Memory Controller v100 ... Found
SPI Nor(cs 0) ID: 0xc2 0x20 0x18
Block:64KB Chip:16MB Name:"MX25L128XX"
SPI Nor total size: 16MB
*** Warning - bad CRC, using default environment
In: serial
Out: serial
Err: serial
Then things get weird. The next line has legible text but some garbage in it, then after that nothing but garbage:
�P���Starting the controller
+*/�)))!) �!�+!%) ! �)*+��
%+���5�! -��5�!
!�!
+-���
!���
�% %!- �)�����+��+ ! %!!5!!�)!+!
+) %%�+
%!5 )
��)5 !5)!) % �)!%
-
%) ) 5)�-�
! )��!� !
- )!
%-
!%! ! !
!��
%)!�% %%)! !� �
%!�)) !)!)!)!%-
�-))! �� ��)))!! ��%
�%!)�!)%)�))% �) %-%+�
�) !�5� ! � ! -!!
)%!
��)�)%�)���)
Is this because the baud rate is suddenly changing? Or is it more likely that the output is switching to some proprietary format?
I also didn't have a super solid connection to the board when trying this, could it be that the connection dropped and then reconnected out of sync or something?