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USB Superspeed Peripherals

WGT_4383351
New Contributor II

In master GPIF project:

FLAGA is set to active high. This is confusing since in the state machine, the transition logic is based on FLAGA or !FLAGA, not FLAGA_Active or !FLAGA_Active, then does it matter FLAGA is set to "active high" or "active low" in master?

A possible explaination si that in the state machine's transition conditions, "FLAGA" means "FLAGA is active" and "!FLAGA" means "FLAGA is not active"? Then if FLAGA is set to active low in master GPIF project, "FLAGA" in transition conditions will means GPIO_21=low and "!FLAGA" will mean GPIO_21=high?

Is that right?

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1 Solution
Rashi_Vatsa
Moderator
Moderator

Hello,

The flags from FX3 slave has polarity Active High which means if for read operation if the DMA buffer is not empty then the FLAG A will be High  and as soon as the DMA buffer is read by master the flag will be asserted low (!FLAG A) on seeing this the master will stop reading the data

This is confusing since in the state machine, the transition logic is based on FLAGA or !FLAGA, not FLAGA_Active or !FLAGA_Active, then does it matter FLAGA is set to "active high" or "active low" in master?

>> Yes this will matter. If you keep the polarity of FLAG as active LOW then the transitions equations need to be changed.

Please refer to

Regards,

Rashi

Regards,
Rashi

View solution in original post

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1 Reply
Rashi_Vatsa
Moderator
Moderator

Hello,

The flags from FX3 slave has polarity Active High which means if for read operation if the DMA buffer is not empty then the FLAG A will be High  and as soon as the DMA buffer is read by master the flag will be asserted low (!FLAG A) on seeing this the master will stop reading the data

This is confusing since in the state machine, the transition logic is based on FLAGA or !FLAGA, not FLAGA_Active or !FLAGA_Active, then does it matter FLAGA is set to "active high" or "active low" in master?

>> Yes this will matter. If you keep the polarity of FLAG as active LOW then the transitions equations need to be changed.

Please refer to

Regards,

Rashi

Regards,
Rashi

View solution in original post

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