If it's not fitted then that's not the problem. If not fitted I have no idea what is causing your problem other than it may have been caused by a zero-ohm pull-up having been fitted previously.Now that the zero-ohm resistor is in DNP, it's not a pull-up to 3V3.
1) Things won't work as they would be expected to.Additionally, please clarify what will happen if we pull up that CS pin to high (always high) by populating that zero-ohm resistor.
2) It could permanently damage or destroy the RP2040.
If the Flash chip CS\ is tied to 3V3 it can never be pulled low so the Flash chip can never be read nor written. This would cause the RP2040 Boot ROM to see the Flash chip as unprogrammed or not fitted so will enter its BOOTSEL MSD mode whenever it powers up.
Whenever the RP2040 sets its CS\ control pin low; excessive current will likely be sunk through the pin which could damage or destroy that pin and potentially the entire RP2040.
If that CS\ control pin has its low-side driver burned out through sinking excessive current it will never be able to pull CS\ low after that.
If that CS\ control pin is partially damaged you may experience unreliable and unpredictable operation, immediately or in the future.
Statistics: Posted by hippy — Wed Jul 24, 2024 9:49 am