AFE7950: DAC to ADC loopback is possible?

Yoonsun Kim

Part Number: AFE7950

HI,

I need to check if DAC to ADC loopback test is possible.

I found useTxCalib among the list of calibration related parameters but didnot find TX to RX loopback enable register in TRM.

If TX to RX loopback is possible in normal mode not in calibration mode, let me know which register I can control and the where the loopback is activated.

Regards,

over 2 years ago

0 Vijayendra Varma Siddamsetty over 2 years ago

TI__Genius 10705 points

Hi Yoonsun,

Only way to loopback analog DAC output to the ADC input is by physically connecting the DAC output to ADC input externally. On the EVM, you can connect DAC output SMA connector to ADC input SMA connector with a cable.

It's not possible to do this loopback internal to the AFE whether in calibration mode or otherwise.

Regards,

Vijay

0 Yoonsun Kim over 2 years ago in reply to Vijayendra Varma Siddamsetty

Expert 1830 points

Hi, Vijay

Is there any way to loopback DAC output to ADC input inside AFE7950?

I think that loopback funcion is required to verify FPGA function without any influence of analog side on custom board.

Regards,

0 Vijayendra Varma Siddamsetty over 2 years ago in reply to Yoonsun Kim

TI__Genius 10705 points

Hi Yoonsun,

As I mentioned above, there's no option to loopback analog DAC output to ADC's analog input internal to AFE.

If you need to loopback, this connection must be done externally.

Regards,

Vijay

0 Yoonsun Kim over 2 years ago in reply to Vijayendra Varma Siddamsetty

Expert 1830 points

Dear Vijay,

I understand that there is no analog loopback inside AFE.

Anyhow I need loopback function to verify FPGA logics. Is there any loopbakc DAC path to ADC path? Can I loopback SRX data to STX on jesd204 block?

Regards,

0 Vijayendra Varma Siddamsetty over 2 years ago in reply to Yoonsun Kim

TI__Genius 10705 points

Hi Yoonsun,

I'm checking with the design team if it is possible to loopback SRX data to STX on JESD block. I will get back to you as soon as I get confirmation from them (latest by Thursday).

Regards,

Vijay

+1 Vijayendra Varma Siddamsetty over 2 years ago in reply to Vijayendra Varma Siddamsetty

TI__Genius 10705 points

Hi Yoonsun,

SRX data loopback to STX can be enabled by programming below register writes:

SPI_Write 0x0016 0x60
SPI_Write 0x7007 0x80
SPI_Write 0x7006 0x00
SPI_Write 0x0016 0x00

Regards,

Vijay

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AFE7950: DAC to ADC loopback is possible?