AD1938 CODEC

Question

HII i actually want to write and read the register(in the ad1938 codec) using microcontroller, but i am not able to get anything in the miso line. I also have given correct addres with read write bit .Could you help me to resolve this.

DaveThib · Accepted Answer

Hello, 
 Glad you have made progress. 
 ad1938 said: pll control reg0- 0x91 
 Bit zero is a "1". This powers down the PLL. Not good. You want to use the PLL. 
 You have the MCLKO pin set to 512 x fs. So that would be 24.576MHz. Are you using the MCLK output of the part? If not then turn it off. 
 So 0x98 would be having the PLL on and the MCLK output pin off. 
 
 ad1938 said: pll control reg0- 0x01 
 I assume this is a typo and you meant to say PLL CTRLReg1? 
 You want the PLL to be the clock source for the DAC. So a value of 0x00. 
 If you really want to direct clock the DAC from the MCLK IN Pin then you MUST input a 512x fs MCLK. A 12.288MHz would be OK for a 24 kHz sampling rate.

ad1938 said: dac control reg 1-0x00 
 Again, I assume you meant Reg 0? 
 This is good. No issues here. 
 
 You have DAC Control Reg 1 as also zero. That is also fine. No problems that I can see. 
 
 ad1938 said: dac control reg 2-0x81 
 You have this as 0x81. 
 The LSB is the Master Mute. If you want to hear anything you need to unmute so clear this bit to clear the mute. 
 The "8" is a tough one. The "1" in the MSB is in a reserved bit location. But, I think this may be wrong but I am actually not certain. I have a part in front of me and when I read it I get an 0x40. Again, the "1" is a reserved bit and I do not have the information to know what it is. 
 
 Thanks 
 Dave T)

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