Warning PR1014 / Generic routing resource will be used to clock signal

[Semnodime]

key_led.gprj

Warnings:

• TA1123
• PR1014

Running placement......
[10%] Placement Phase 0 completed
[20%] Placement Phase 1 completed
[30%] Placement Phase 2 completed
WARN  (TA1123) : the clock "osc_clk"'s frequency does not match internal_osc_inst/osc_inst/OSCOUT's 
[50%] Placement Phase 3 completed
Running routing......
[60%] Routing Phase 0 completed
[70%] Routing Phase 1 completed
[80%] Routing Phase 2 completed
WARN  (PR1014) : Generic routing resource will be used to clock signal 'sys_clk_d' by the specified constraint. And then it may lead to the excessive delay or skew
[90%] Routing Phase 3 completed

[kyonmiriam]

Hi

• For the WARN (TA1123), it is just a bug for GOWIN IDE. Due to decimal precision issues in Timing Constraints Editor, 70MHz will finally constrained to 69.9999MHz. However 70MHz≠ 69.9999MHz...

So, why is this osc_clk 70MHz? According to the description on page 110 of Chapter 6 of UG306E:

𝑓𝐶𝐿𝐾𝑂𝑈𝑇 = 𝑓𝑜𝑠𝑐/FREQ_DIV

However, the English version of the manual does not say what the frequency of this OSC is. In the same position in the Chinese version of the manual, you can see that the frequency of this OSC is 210MHz.

In this demo, FREQ_DIV is set to 3, so the osc_clk = 210/3=70MHz

• For the WARN (PR1014), this is because the IO used by the external oscillator (aka. P16 or EMCCLK) is not GCLK PIN. Generally, this warning should be ignored unless your system involves the synchronization of multiple non-source clocks.

[Semnodime]

Thanks for the explanation, this provides sufficient details for both warnings and I can now ignore them without fearing unforseen consequences.