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Visitor fanlly
Visitor
4,372 Views
Registered: ‎03-17-2014

AXI GPIO max rate?

Hello,

I use one GP AXI Master Port to extend IO by adding AXI Interconnect IP and AXI GPIO IP. I test AXI GPIO rate, only 2MHz-3MHz.
In SDK, using code below
while(1)
{
  XGpio_DiscreteWrite(&LED_Ptr, 1, 0xffffffff);
  XGpio_DiscreteWrite(&LED_Ptr, 1, 0x00000000);
}
When I set FCLK_CLK0 100MHZ, GPIO rate is about 2.3MHz.If FCLK_CLK0 200MHZ, GPIO rate is about 3.6MHz.
I think it is too slow. What is the max rate for AXI GPIO? How to config ZYNQ to max AXI GPIO rate? Thanks!

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6 Replies
Visitor hobbin
Visitor
4,344 Views
Registered: ‎07-07-2014

Re: AXI GPIO max rate?

Hi fanlly,

 

I'm also experimenting with the AXI GPIO. I saw your post in the Zedboard forum where someone suggested using a function inside of XGpio_DiscreteWrite. I thought this was a good idea for a software approach.
I cannot find the function definition for XGpio_DiscreteWrite. I'm unsure how to find it. The documentation seems to be in HTML format. Maybe my program to open it (Chrome) isn't handling it correctly.

 

If I were going to blink LEDs at a certain rate (I am trying to, actually) I would tie the LEDs to a clock divider which was connected to the fabric clock.

--
if you plan on being original, plan on being copied
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Xilinx Employee
Xilinx Employee
4,341 Views
Registered: ‎08-02-2007

Re: AXI GPIO max rate?

Hi,

 

The function XGpio_DiscreteWrite is included in the following driver code xgpio.c

$SDK_Install\sw\XilinxProcessorIPLib\drivers\gpio_v3_01_a\src

 

--Hem

 

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3,766 Views
Registered: ‎06-25-2014

Re: AXI GPIO max rate?

Hi,

I have the same slow rates problem.

have you found a solution to increase the rate ?

 

Thanks,

Shai

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Teacher muzaffer
Teacher
3,760 Views
Registered: ‎03-31-2012

Re: AXI GPIO max rate?

It's quite difficult to push AXI GPIO below 100ns. What speed do you need? If you want really high speed, the best choice is to move some of the logic into PL.
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Visitor hb18678
Visitor
2,404 Views
Registered: ‎03-16-2013

Re: AXI GPIO max rate?

What is the reason we can't push it? 

 

I am writing a device driver to update the display which is 320 x 240 x 24 bit.  So if it's 2.5MHz, then my application will do nothing but update the display assuming 30 fps.

 

 

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Teacher muzaffer
Teacher
2,400 Views
Registered: ‎03-31-2012

Re: AXI GPIO max rate?

It's a fundamental limitation of the AXI GP ports. If you want high speed, you need an AXI master in PL to read the frame buffer from the ddr itself.

 

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