Hi,
I just turned on 5 proto boards with OMAPL138. On one of them I start seeing something funny.When booting from SPI1 FLASH, the SPI1 CLK signal looks different, weaker than on other boards (softer edges, just making it to 4MHz). More over, in Reset the SPI1 CLK level is about 1V (or 1.2V, or 1.8V) not 3V ( I'm using 3.3V for all I/O banks). After boot, it reverts to 3.3V levels. Once in a while, it behaves worse: upon exiting from reset the SPI1 CLK is swinging between 1V (or 1.2.V or 1.8V) and 3.3V, failing to load from FLASH.There are times when this specific OMAP behaves exactly like other boards I have (normal).
I assume that all 5 board are identical. I checked and I think that I followed correctly the recommendations for power sequencing: 1.2V->1.8V->3.3V. Power rails look good.I'm using default hardware setup for booting.
I don't see any other issues with specific board once it is up and running. Shall I suspect this specific device, maybe it got upset in assembly, handling, etc? Shall I try to replace it? Are there any external conditions at pins (at reset, or power on) that create this SPI1 CLK pin behaviour?
Many thanks,
Nick