AVR 325/525/7200: RS-232 Port Instructions
Version 1.1 - Revised 6-Jan-2003
Page 3 of 5
Command Transmission Sequence
Each command consists of a four byte hex command from the table attached to this
document. To send a command, first find the hex code listed in the chart for the specific
function. Convert each byte to binary, and then precede each byte with a start bit (“0”)
and follow it with a stop bit (“1”). Make certain that the time for the transmission of all
four bytes does not exceed 107 ms., as the AVR will interpret a time gap greater than
108ms as the start of a new command.
Thus, to send the “80,70,C1,3E” hex code sequence to issue a “MUTE” command, the
sequence would be as follows: including the start and stop bit after each hex code,
0 0000 0001 1 0 0000 1110 1 0 1000 0011 1 0 0111 1100 1
BYTE 1 BYTE 2 BYTE 3 BYTE 4
TOTAL STRUCTURE FOR THE FOUR-BYTE COMMAND
When building a sequence with multiple commands, remember to insert a time delay so
that the total time from the start of one four-byte command to the start of the next four-
byte command is at least 108ms.
Thus, when sending multiple commands, the transmission sequence will be as follows:
COMMAND 1
COMMAND 2
COMMAND 3
------- 108 ms. --------- ------------ 108 ms--------- ------108 ms----
The protocol for code transmission does not allow for “repeat” or continuous code.
Thus, in the case of commands such as the Volume control where the button would be
held down when using the actual remote, the individual “volume up” or “volume down”
command must be sent individually as many times as necessary to achieve the desired
effect.
