Hi Steve, As you said, DMA was tranferring two samples to transmit buffer register when the slot size was configured to 16. When I changed it to one sample (i.e.,16 bit) it worked, and now the FS= 8KHz. Thanks a lot ! Regards JK
------- Original Message ------- Sender : Steve Chen<[email protected]> Date : Jul 27, 2010 21:36 (GMT+09:00) Title : Re: DM6467 McASP Frame Sync On Tue, Jul 27, 2010 at 6:08 AM, Jaya krishnan wrote: > > Hi > We have some design issues with interfacing DM6467 McASP to a third party > DAC.(CS4353- A paasive DAC with stereo output) > We actually tried to replace AIC33 with CS4353. In the board which uses > AIC33 , McASP is receiving Serial clk and FS from AIC33. > But in our board, we can't provide Serial clk and FS from DAC and hence > McASP gives FS to DAC . Serial clock is provided by > a CDCE949 clk synthesizer. (I have attached the connection diagram). > The problem is , the FS generated by McASP is governed by the follwoing > relationship > FS= Serial clk/(slot size * No of Slots) > I have given serial clk=256KHz, slot size=32, I2S and FS=4KHz. And I get > the output quite normally. > I am confused in this. > 1) How can a data (speech )sampled at 8KHz, 16 bit sample width plays > normally at FS= 4KHz? As you point out, at FS=4kHz, serial clock is 256KHz which provide enough cycles to shift out 8Kb/s of data. > If I change the slot size to 16 bit , FS becomes 8 KHz, and the audio > plays at double speed. > 2) Why is it like that? May want to check out the DMA settings. I suspect DMA engine is still grabbing 32 bits at a time but at double speed. Regards, Steve Jayakrishnan M M Research Engineer R&D Team-2 , Group-5 Security Solutions Division SAMSUNG TECHWIN CO.,LTD TEL +82-70-7147-8482 FAX +82-31-8018-3712 Mobile +82-10-6409-3619 E-mail:[email protected] <img src='http://ext.samsung.net/mailcheck/SeenTimeChecker?do=b9201a3ec71f120aede8971f34235520a3ba47c6e2722fe244c26a66f18aa08bcce5e516161401cc9c32f6c4c9345bd3745cd22ca5f3b0788945cf8dfc8cc7cb8a2769b5088e593e5f96817860e2d78ddb9fdddda33e82cbe4a391424e62fcf6cf878f9a26ce15a0' border=0 width=0 height=0 style='display:none'> _______________________________________________ Davinci-linux-open-source mailing list [email protected] http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source
