User guide

6 HDMI5 Component Video Switch
and the Error Response is always the string:
!ERR<CR><LF>
By parsing only the prefi x characters ‘+’ and ‘!’, a programmer can chose to ignore the error codes and simply look at the fi rst characters of the response strings and use them as a pass / fail indicator when issuing a command. All response strings always end with a <CR><LF>. A Query Response string always starts with the ‘=’ characters and is followed by a command string indicating the parameter being returned. This is better explained in an example. Here’s an example of a querying a device for its light intensity settings:
LI?<CR> Sent: Light Intensity Query command +<CR><LF> Received: Acknowledgement of command =LI 2,13<CR><LF> Received: Light Intensity Query Response
Note that a “+<CR><LF>” followed the command string. A command string is always followed by either an Acknowledgment (as in this case) or an Error Response. This consistency allows a driver to use a single routine to issue a command and check for an Acknowledgement or an Error Response String, whether or not the command queries for a response. An example of an error response:
IL?<CR> Sent: Command characters transposed, no such command !2<CR><LF> Received: Error Response indicating unknown command
In this case the Error Response string “!2<CR><LF>” was issued instead of the acknowledg- ment string since the command was not recognized. Response String Checksums and CRC-8 Checkcodes Response strings can be programmed to have checksums or CRC-8 checkcodes appended to them, the syntax is identical to the Command Structure’s checksum and CRC-8 handling. Checksum and CRC-8 are turned on and off by issuing the proper command. On most devices this is the “Control Settings” command. Only the Error Response and The Query Response strings will have checksum and CRC- 8 checkcodes appended to them. The Acknowledgment Response will always consist of “+<CR><LF>”. Anything else must be assumed to be a communication error. An example with checksumming enabled, while querying for LED intensities is:
LI?<CR> +<CR><LF> =LI 2,13;239<CR><LF>
K.I.S.S.™ (Continued)
23HDMI5 Component Video Switch
XS $ Back up current settings into EEPROM. XS ? Query for current settings. XS Query for current settings. Response String: =XS settings Where ‘settings’ is a bitmapped parameter:
Decimal Value +128 +64 +32 +16 +8 +4 +2 +1 Bit Position 76543210 Name 12V CRC CSE IRJ IRS IRE FP AS Factory Settings: 00011110
AS - 0=Master / Slave mode. 1=Asynchronous Mode. KB - 0=Disable Front Panel. 1=Front Panel Enabled IRE - 0=Disable IR Control. 1=Enable IR Control. IRS - 0=Turn off IR Sensor. 1=Turn on IR Sensor. IRJ - 0=Turn off IR Jack. 1=Turn on IR Jack. CSE - 0=Disable CS and CRC-8 1=Append either Checksums or CRC-8 to responses. CRC - 0=Append Checksums, 1=Append CRC-8’s, to responses. 12V - 0=+12V disabled 1=Use IR Jack as +12V On / Off Control
The ‘$’ parameter is a “Backup Control Settings” fl ag. If it exists, then the current settings will be backed up in EEPROM, and will remain unchanged through a power failure. Backing up the “Control Settings” will also backup the “Extended Control Settings”. The IR control (IRE) and the IR jack (IRS), work differently when disabled. Disabling IR control, by setting the ‘IRE’ bit to zero, keeps the HDMI5 from responding to any IR codes, however the front panel sensor remains operational and any codes received can still be queried for by using the “IR ?” command. Disabling the IR sensor (IRS) and enabling IR control (IRE), allows the HDMI5 to respond to IR signals through the IR jack, any signal received by the IR sensor will be ignored. Disabling the IR jack, by setting the ‘IRJ’ bit to zero, completely disables the IR jack. IR com- mands are no longer be received through the IR jack if the ‘IRJ’ bit has been set to zero. The ‘IRJ’ fl ag and ‘12V’ are mutually exclusive. Any attempt to set them both will result in the ‘12V’ being disabled.
HDMI5 Command Ref. (Cont’d)