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Asynchronous clock warnings (STA) for a SPI based PSoC Creator project

Last Updated: June 23, 2011

Question: I'm getting around 11 STA warnings when I compile a PSoC 3/5 project with SPIM & SPIS. What is the significance of these warnings?


Following is the pattern of warning message which you may get: (clock1, clock2, reg1 & reg2 are for example)

sta.M0011: Clock "clock1" at "reg1" is asynchronous to clock "clock2" at "reg2".

Descrption for this warning message: (PSoC Creator Topics)

The static timing analyzer could not detect the relationship between the clocks. To cross clock domains safely, use a synchronizer.

Actual Reason for this warning message:

For SPI Master as well for SPI Slave, the input synchronized option in the Input pins has to be unchecked. But PSoC Creator 1.0 can't detect that this is a valid configuration and it will use the Static Timing Analysis similar for a normal design. As the input pin is not snychronized to internal BUS CLOCK, STA tool will detect this asynchronous connection and hence the warning


This is applicable to MISO (SPIM) & MOSI, SCLK, SS (SPIS) input pins:

So it is safe to ignore these warning messages.

Note: If you are getting setup time & slew violation related warning messages, Please refer to this KB.

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