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AD9911 general questions

Question asked by tweekzilla on Jul 29, 2014
Latest reply on Jul 31, 2014 by sitti

Hi all,

 

I have some pretty basic questions and a possible board design screw up.  My initial aim is to simple read out the CSR register (0x00). I'm using a 3-wire SPI interface (and attempt to set the CSR <2:1> to 01) - Method:

 

SET REGISTER

1) set CS low

2) Send 0x00 (write to CSR register)

3) Send 0b11110010 (enable 3-wire)

4) set CS high

5) set io_update high

6) set io_update low

 

READ REGISTER

1) set CS low

2) send 0b10000000 (read CSR register)

3) send 0x00 (and look at what is on the SDIO_2 pin on a scope)

4) set CS high

 

I'm currently not seeing any bits on the pin, however, below might explain why and any input is appreciated

 

1) I stupidly tied MASTER_RESET to PWR_DWN_CTRL to GND on the board.  Do I have to do a MASTER_RESET on power up? Someone mentioned in another post that you may be able to initate a MASTER_RESET by sending 32 1's to the chip?

 

2) I'm waiting for my balun to turn up so I do not have a REF_CLK.  Will the DDS register read just not work without this (I suspect this is my issue)?

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