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Honored Contributor I
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GXB tx_coreclk source problem

Hi! 

 

Quartus prime 16.1.1 Build 200 11/30/2016 Sj Standard Edition 

PartNumber EP4SGX530NF45C2 

 

I have the following problem: 

I'm trying to configure a PCIe serdes (alt_gxb) and I need to drive transmit clock from PLL (not from serdes output clock). 

According to the Stratix IV handbook (Volume 2, table 2-16), I need to set "GXB 0 PPM core clock" setting from PLL output to serdes data output: 

set_instance_assignment -name GXB_0PPM_CORE_CLOCK ON -from "pll_125:pll_125_inst|altpll:altpll_component|clk" -to serdes_TX_P 

 

But it does not help. 

I keep receiving the error: 

 

Error (167028): Input port CORECLK of GXB Transmitter channel PCS "serdes_1x:DUT|serdes_1x_alt4gxb:serdes_1x_alt4gxb_component|transmit_pcs0" must be fed by output port CLOCK_OUT of GXB Transmitter channel PCS "serdes_1x:DUT|serdes_1x_alt4gxb:serdes_1x_alt4gxb_component|transmit_pcs0" because the GXB transmitters have the same clock rate or are operating in bonded x4/x8 mode 

 

 

If I drive transmit clock from another GXB and have this setting "GXB_0PPM_CORE_CLOCK" configured - that causes no error in compilation. 

But I need to drive it from PLL. 

 

The handbook claims I can drive 

"Clock output from left and right and top and bottom PLLs (PLL_L, PLL_R, and PLL_T, PLL_B)" 

The partnumber has a few PLLs, named (PLL_B1/2, PLL_T1/2, PLL_L1/2/3/4, PLL_R1/2/3/4) but making a location assignment does not affect the error. 

 

Any advice? 

 

 

p.s. attached a project template with the error
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