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Observer julian3
Observer
707 Views
Registered: ‎07-14-2016

Reusing Selectmap Configuration Pins ???

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Good morning!

 

I am designing a board which has an Artix-7 (xc7a50tftg256) configured in slave selectmap mode through Cypress FX3S proprietary GPIF II interface. After configuration, I intend to reuse the same 16-bit parallel interface for data transfer. Furthermore, the FPGA will be re-configured arbitrarily during runtime. 

 

I have already verified that the GPIF II bus can be repurposed in runtime on the microcontroller side. 

 

Can selectmap D0-D15 be reused as GPIO after configuration?

Must special care be taken to move these pins to high impedance before lowering PROGRAM_B?

Is CCLK reusable as a clock output?

 

TIA

 

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Moderator
Moderator
959 Views
Registered: ‎09-18-2014

Re: Reusing Selectmap Configuration Pins ???

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julian3,

 

 

Can selectmap D0-D15 be reused as GPIO after configuration?

 

-Yes, they're multi-function IOs. See "Configurations Pin Definitions" Table 2-4 in UG470. Make sure PERSIST is NOT set. You should also understand by doing so you will not be able to do readback post config as the data pins will revert to user I/Os after configuration.

 

 

Must special care be taken to move these pins to high impedance before lowering PROGRAM_B?

 

-Not that I know of. During normal power-up and before configuration, these pins should already be tri-stated as per datasheet. Once the configuration is initiated by pulsing PROGRAM_B, PUDC_B will dictate the IO state until the mode pins are sampled and bitstream loading begins. Still, make sure there are no scenarios in which datasheet recommended operating parameter are violated.

 

 

Is CCLK reusable as a clock output?

 

-Yes, check out the USRCCLKO port of STARTUPE2 primitive detailed in Chapter 5 of UG470.

 

 

Regards,

T

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2 Replies
Moderator
Moderator
960 Views
Registered: ‎09-18-2014

Re: Reusing Selectmap Configuration Pins ???

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julian3,

 

 

Can selectmap D0-D15 be reused as GPIO after configuration?

 

-Yes, they're multi-function IOs. See "Configurations Pin Definitions" Table 2-4 in UG470. Make sure PERSIST is NOT set. You should also understand by doing so you will not be able to do readback post config as the data pins will revert to user I/Os after configuration.

 

 

Must special care be taken to move these pins to high impedance before lowering PROGRAM_B?

 

-Not that I know of. During normal power-up and before configuration, these pins should already be tri-stated as per datasheet. Once the configuration is initiated by pulsing PROGRAM_B, PUDC_B will dictate the IO state until the mode pins are sampled and bitstream loading begins. Still, make sure there are no scenarios in which datasheet recommended operating parameter are violated.

 

 

Is CCLK reusable as a clock output?

 

-Yes, check out the USRCCLKO port of STARTUPE2 primitive detailed in Chapter 5 of UG470.

 

 

Regards,

T

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Don’t forget to reply, kudo, and accept as solution.
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Observer julian3
Observer
664 Views
Registered: ‎07-14-2016

Re: Reusing Selectmap Configuration Pins ???

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Thanks T!

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