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AD9958 Troubleshooting

Question asked by EA4FRB on Mar 19, 2011
Latest reply on Mar 23, 2011 by EA4FRB

I have developed a board using the AD9958 and I'm not able to have it working. Initially I had the DVDD_I/O voltage at 2.8V and I thought that it was the cause of the problem, but after changing to 3.3V the problem continues. I have checked that all power supplies, the oscillator is running, and the SPI interface signals and SW managing them are also correct; but the DDS does not generate any signal.

 

In order to check the SPI interface, I did a simple test by configuring the SPI in single-bit three-wire mode and perform a read operation of the CSR, but the SDIO_2 did not output any signal. Therefore it looks like the DDS is not recognizing the SPI commands.

 

I have two boards with the same behaviour and I'm wondering if I have a HW design problem or I damaged the AD9958 devices during the board assembly.

 

For the testing, the SW is doing the following sequence:

 

- PWR_DWN_CTL = LOW

- IO_UPDT = HIGH

- CS = HIGH

- RESET = HIGH

- Delay(2ms)

- RESET = LOW

- Delay(2ms)

- CS = LOW

- WR_CSR (0xc0)          // Writes 0xc0 in the CSR register

- CS = HIGH

- IOUpdate()                  // IO_UPDT=LOW --> IO_UPDT=HIGH

- LOOP(forever)

    - CS=LOW

    - RD_CSR()                  // Reads CSR register

    - CS=HIGH

 

Note: SDIO_3 and SDIO_1 are connected to ground

 

I'll appreciate any hint for the troubleshooting of the problem.

 

Thanks,

EA4FRB

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