NEC E series volume control

jbhav683

I've been tasked with controlling an NEC E series LCD. One of the features requested is volume control. NEC neglected to include volume ramping in their API, so I'm left with direct volume set commands. I've tried numerous ways and so far I have been unsuccessful at recreating the correct HEX string through a function for ramping the volume.

The E series volume set command for setting the level to 25 is:
01 30 41 30 45 30 41 02 30 30 36 32 30 30 31 39 03 78 0D

The HEX that changes when ramping up or down is the 5th and 4th HEX characters from the end of the command, $31 $39, and the CKS $78.

I'm not getting the concept of MSB and LSB, and when it comes to getting the checksum the XOR math is throwing me for a loop.

I've included the manuals that NEC teir 2 sent me along with their best wishes and good lucks.

Does anyone have a routine or a module that could help me either understand how to accomplish the last of ramping volume on the NEC E series LCD, or would actually accomplish the task at hand?

Any help would be greatly appreciated.

regallion

Ah yes I remember this protocol. I haven't used a driver using AMX but I did write one for another control system.

The thing to remember when calculating the checksum is don't include the SOH (byte 1).

I don't have access to any of the code I wrote at the moment but perhaps that's why you're not getting the checksum to calculate properly?

Also, have you tried the AMX driver? There's some duet modules there. Most NEC TVs all use the same codes so I'm sure you'll find one that works.