Ultrazed EV sysclk

Question

In our design we'd like to use the PL SYSCLK but we found that is not present. Further investigation showed a strange red cross in the scematics of the SOM on resistor R92 which is also not present on the SOM. That resistor is placed between 3.3V and the enable(?) of the clock generator. Is there a reason for this? Can we place a 42k resistor and use it without other modifications? I could not find anything in the datasheets concerning this.

pietervanderstar · Accepted Answer

We had a simple design (pwm) and hooked that up to a clock wizard to get the diff clock to a single-ended one. The output of the locked and pwm (and clock output of the wizard) were hooked up to LEDs which did not light up. When we hooked up a button direcly to a LED that one responded. So we suspected the clock. We thought about measuring the clock, but could not find a good point on the board to probe. When we saw the big red cross on the resistor we thought that was strange and thought about asking first.

My collegue jus said she had to swap the pin locations of the system clock from the master xdc file as the documents specified different locations.

set_property PACKAGE_PIN AC7 [get_ports {PL_SYSCLK_N}];
set_property PACKAGE_PIN AC8 [get_ports {PL_SYSCLK_P}];

Maybe we'll try with a refence design first and see if we can find out what we did wrong.