LM4550 Audio Codec

Apr 27, 2005 2 Replies
E

Hey Guys,



I'm running into this insane problem just trying to play some ordinary wave file on a LM4550 audio codec on the XUP board

formatting link
(I don't know if this board is widely used yet, but I'm posting a link anyway). The problem is that audio codec plays the pcm file cleanly (i.e. no static) but certain parts of the file are repeated during playback (so if the wave file contained someone saying "1 2 3", it playbacks "1 1 2 2 3 3") The data resides on a SRAM module connected to the expansion headers on the board. I'm certain that the data itself isn't corrupted. I have verified my design several times in simulation and the address generation to access audio data from the SRAM seems fine.



I guess what I'm wondering is, is there something werid about configuring the LM4550 that I'm missing and that maybe causing this. I configure the following registers on the LM4550 which are on the playback path:



Register: 02h Value 00h (Line out, unmute) Register: 04h Value 00h (Headphone, unmute) 18h Value 00h (PCM Gain, unmute) 20h value 80h (To bypass the 3D Sound Circuitry) 0Ah value 00h (to mute the PC Beep input)



Any insights to configuring/using the LM4550, would be really appreciated.



Thanks.



Vote
Twitter Facebook LinkedIn
E

Hey Guys,

I'm running into this insane problem just trying to play some ordinary wave file on a LM4550 audio codec on the XUP board

formatting link
(I don't know if this board is widely used yet, but I'm posting a link anyway). The problem is that audio codec plays the pcm file cleanly (i.e. no static) but certain parts of the file are repeated during playback (so if the wave file contained someone saying "1 2 3", it playbacks "1 1 2 2 3 3") The data resides on a SRAM module connected to the expansion headers on the board. I'm certain that the data itself isn't corrupted. I have verified my design several times in simulation and the address generation to access audio data from the SRAM seems fine.

I guess what I'm wondering is, is there something werid about configuring the LM4550 that I'm missing and that maybe causing this. I configure the following registers on the LM4550 which are on the playback path:

Register: 02h Value 00h (Line out, unmute) Register: 04h Value 00h (Headphone, unmute) 18h Value 00h (PCM Gain, unmute) 20h value 80h (To bypass the 3D Sound Circuitry) 0Ah value 00h (to mute the PC Beep input)

Any insights to configuring/using the LM4550, would be really appreciated.

Thanks.

Vote
Twitter Facebook LinkedIn
E

Umm - just a suggestion to fellow novice hardware designers: try another piece of hardware if your design seems perfect and it doesn't work. Damn board had a stuck-at-0 fault on one of the expansion header pins. Wahooo.

Matter closed.

Vote
Twitter Facebook LinkedIn

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required