AFE7900EVM: NCO frequency control using GPIO pins

Loot Goblin

Part Number: AFE7900EVM
Other Parts Discussed in Thread: AFE7900

Tool/software:

Hey,

I'm trying to control the 16 NCOs present in each channel for the AFE7900, however, the GPIO pins are connected to the internal FPGA.

How can I communicate with the said FPGA to control these GPIO pins?

Also, do the NCO select lines (RX/TX_NCOSEL_0/1/2/3) act as MUX select lines to switch between the 16 NCOs?

7 months ago

+1 Loot Goblin 7 months ago

Prodigy 20 points

Hey,

I'm following up on my query regarding controlling the 16 NCOs via the FPGA's GPIO pins and clarification on the NCO select lines' role as MUX select lines.

Thank you for your assistance.

Best regards,
LG

+1 Camilo Garcia Trujillo 7 months ago in reply to Loot Goblin

TI__Expert 4925 points

Hi,

The NCO select lines can be mapped to any of the available GPIOs. These inputs can be set to ‘Logic High =1’ or ‘Logic Low =0’ to switch between NCOs. Could you elaborate to what FPGA you are referring to?

The 4 NCO select lines act like a typical MUX select. Take the table in the documents below as an example.

AFE79xx_16_TX_NCOs.pdf AFE79xx_16_RX_NCOs.pdf

Best,

Camilo

0 Loot Goblin 7 months ago in reply to Camilo Garcia Trujillo

Prodigy 20 points

Hey,

Thank you for the reply. Apologies for the confusion; I was referring to the CPLD present on the board. While checking the schematic, I found that the GPIO lines are connected to the CPLD. How can I control these GPIO lines?

Best regards,

+1 Camilo Garcia Trujillo 6 months ago in reply to Loot Goblin

TI__Expert 4925 points

Hi LG,

Our recommendation would be to use any of the following GPIO pins (D5,G10,T6,T5,N16 or N15)that are routed to test points and remove the resistor that connects them to the CPLD. As control through the CPLD is currently not supported.

Best,

Camilo

0 Loot Goblin 6 months ago in reply to Camilo Garcia Trujillo

Prodigy 20 points

Hey Camilo,

Thank you for the reply, I'll try proceeding with this.

Best Regards,

0 Camilo Garcia Trujillo 6 months ago in reply to Loot Goblin

TI__Expert 4925 points

Hi LG,

No problem.

Best,

Camilo

0 Loot Goblin 6 months ago in reply to Camilo Garcia Trujillo

Prodigy 20 points

Hey Camilo,

I have another query. I need to control both RX and TX NCOs, so I need 8 GPIO pins to control them. Can I use any other GPIO pins connected to the CPLD, such as P16, C6, F6, V6, N10, etc.?

Thanks,

0 Camilo Garcia Trujillo 6 months ago in reply to Loot Goblin

TI__Expert 4925 points

Hi LG,

The ones you have mention can be used as long as you can disconnect the GPIO from anything else in the board that might interfere and still connect it to your control signal. Any of the non fixed GPIOs can be used.

Best,

Camilo

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AFE7900EVM: NCO frequency control using GPIO pins