ad1938 in TDM mode

Question

i am sending TDM frame with 8 channel throughDSDATA1 ,and frame_sync to DLRCLK(HDR 1),scl to DSCL(HDR-1), and keeping S4 in 'A' position for TDM mode , in this condition only DAC 1 is able to get the data , but other DAC are not getting data, i am providing 12.2mhz data from board. 
 In my 8channel frame in all 8 channel data is there , i want to run all channels according to frame data, but un-fortunately i am not getting data except DAC 1(CH-0 &CH-1) , what other changes do i need to do ,Moreover there is no separate TDM mode on the DAC control register, only stereo, daisy chain. and dual - line TDM modes are there. 
 Please tell me the steps and configurations to run all 8 channels in TDM mode.

Harishgowtham · Accepted Answer

Hello, 
 If you want to get 8 channels out of the DAC, then you must set the DAC in the TDM (Daisy chain) mode. 
 If you connect your external data pin (which is carrying 8 channels) to the DSDATA1 pin along with the serial clocks to DBCLK,DLRCLK pins, then you can see the output on all 8 analog output pins (DAC1L,DAC1R,DAC2L,DAC2R,DAC3L,DAC3R,DAC4L,DAC4R). 
 Regarding the switch position, 
 S4 position should be at 'A' for TDM8. 
 Please refer the below pic if you are using Sigma studio for programming the AD1938. 
 
 If you are using a uC for programming, then set the value 0x40 at the address 2. 
 Regards, 
 Harish)

Harishgowtham · Answer

Hello, 
 Sorry for the delay in response. 
 Have you figured out what was going wrong? If you are still facing a problem with this, then I will be happy to help you. 
 
 ad1938 said: as in TDM mode only one output (DAC1)is enable ,so it possible to control all 8 DAC in TDM frame(8 channel frame) in AD1938 evaluation board. 
 Yes, it's possible to mute all 8 DAC channels individually using the mute registers. I put the AD1938 DAC section to TDM8 mode, and feeding the clocks and data for TDM8 from the sigmaDSP (I'm using ADAU1466Z eval board), I can see 8 channels coming out of the DSP and connected to DSDATA1, and I can see the respective analog signals on all DAC pins (DAC1L/R to DAC4L/R), If I move the slider up and down, then the respective channels are scaled. 
 
 Kindly do reply if you need any assistance. 
 Regards, 
 Harish

Harishgowtham · Answer

Hello, 
 Those things you can set accordingly between the Tx and Rx. 
 I believe rest works fine. 
 Regards, 
 Harish

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ad1938 in TDM mode

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