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MEmel1
Beginner
1,232 Views

Why there's no clock on afi_clk output of the Hard DDR3 Memory Controller, although clock on pll_ref_clk input is present?

I've a problem running DDR3 HMC on Cyclone V SoC Development Board. I instantiated HMC megafunction in schematic top level file, made mem_ pin assignments, connected pll_ref_clk pin to CLK_BOT1 board clk which provides 100MHz, made successful compilation and trying to read/write data using Avalone MM interface. But HMC makes no responce and there's no clock on afi_clk, which suppose to run at 400MHz, according to the settings.

 

What could be the reason for that?

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6 Replies
NurAida_A_Intel
Employee
31 Views

Dear MEmel1,

 

For first step, I recommend you to generate the board test system example design in https://www.intel.com/content/www/us/en/programmable/products/boards_and_kits/dev-kits/altera/kit-cy... and compare your design setting with the golden design.

 

Thanks

 

Regards,

NAli1

 

MEmel1
Beginner
31 Views

Thanks for the reply, NAli1,

 

I actually did that. Basically I set the same settings in my megafunction as in fpga_sdram Qsys component of the reference design. The differences are only in chip/board timing constrains, in physical chip interface width (reference design uses two DDR3 chips as opposed to mine which uses one), and in Avalone MM interface width. But I can't see how are these differences relevant to the complete absence of UniPHY generated clock (afi_clk). The clock settings are the same as are the pin assignments.

 

I was going to check the same afi_clk clock in reference design, but run into another trouble using Qsys: i can't export component pin which is also used internally. It's avaliable ether for internal use, or for export.

sstrell
Honored Contributor II
31 Views

What is your indication that afi_clk is not running?

 

You can get any interface out of a Platform Designer system by adding in a bridge component and exporting the extra interface. You'd use a clock bridge component for this, but since you are using the hardened interface, I don't know if it's possible to connect that back to soft FPGA logic.

 

Are you seeing the user clock coming from the IP?

BoonT_Intel
Moderator
31 Views

Hi, If you trace the RTL, you can see the afi_clk is direct connect from the PLL out_clk port.

So, the only reason why no clock is due to PLL is lose lock.

Can you monitor is the PLL_LOCK signal assert?

MEmel1
Beginner
31 Views

--- Quote Start ---

 

You can get any interface out of a Platform Designer system by adding in a bridge component and exporting the extra interface. You'd use a clock bridge component for this, but since you are using the hardened interface, I don't know if it's possible to connect that back to soft FPGA logic.

 

--- Quote End --- 

Thanks for the information, I'll keep that in mind for future Qsys usage.

 

--- Quote Start ---

 

Hi, If you trace the RTL, you can see the afi_clk is direct connect from the PLL out_clk port.

So, the only reason why no clock is due to PLL is lose lock.

 

--- Quote End --- 

 

That piece of advice was very helpful, thank you. On RTL view I noticed that PLL's reset is inverse. There's a standart inverse symbol on PLL reset pin.

I guess, on top level schematic view leter "n" at the end of megafunction reset pin name ( global_reset_n) stands for "negative" and means the same.

That was a bit unexpected :-)

Turns out, I 've keeping the controller in reset all the time, no wonder everything seemed dead.

 

So far so good, the afi_clk is running now :-)

BoonT_Intel
Moderator
31 Views

Good to know!😄

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