7 communication protocol, Communication protocol, Table 4: structure of the protocol – Kramer Electronics 7508 User Manual
Page 12: Table 5: instruction set for the 7508, 7communication protocol
KRAMER: SIMPLE CREATIVE TECHNOLOGY
Communication Protocol
10
7
Communication Protocol
RS-232 communication with the 7508 complies with the following protocol.
The protocol uses 4 bytes of information, and data is at 9600 baud, with no
parity, 8 data bits and 1 stop bit.
Table 4: Structure of the Protocol
MSB
LSB
INSTRUCTION
0
TO PC
I5
I4
I3
I2
I1
I0
7
6
5
4
3
2
1
0
1st byte
DATA
1
D6
D5
D4
D3
D2
D1
D0
7
6
5
4
3
2
1
0
2nd byte
EXTENDED DATA
1
E6
E5
E4
E3
E2
E1
E0
7
6
5
4
3
2
1
0
3rd byte
MSB’s
ADDR
1
E7
D7
0
0
1
1
0
7
6
5
4
3
2
1
0
4th byte
Note that the MSB’s of the DATA (D7) and the EXTENDED DATA (E7) are in the fourth byte.
Terminology:
•
TO PC is the “DESTINATION BIT”
•
I4..I0 is the “INSTRUCTION”
•
D7..D0 is the “DATA”
•
E7..E0 is the “EXTENDED DATA”
•
A0 is the “LSB of the MACHINE ADDRESS”
The destination bit, TO PC, is 0 when sending from the PC to the machine, or 1 when sending from the machine to the PC.
Table 5: Instruction Set for the 7508
#
INSTRUCTION
I5 I4
I3 I2 I1 I0
0
Reset
0
0
0
0
0
0
1
Read video standard
0
0
0
0
0
1
3
Read back-panel DIP-switch 1 (video format CV/YC) 0
0
0
0
1
1
10
Write EEPROM data – low address
0
0
1
0
1
0
11
Read EEPROM data – low address
0
0
1
0
1
1
12
Write I²C
0
0
1
1
0
0
13
Read I²C
0
0
1
1
0
1
16
Error
0
1
0
0
0
0
57
Enable “Power-down save”
1
1
1
0
0
1
61
Identify machine
1
1
1
1
0
1
1 Note that the MSB’s of the DATA (D7) and the EXTENDED DATA (E7) are in the fourth byte