SOF interrupts in the CY7C64613 (FX) | Cypress Semiconductor
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SOF interrupts in the CY7C64613 (FX)
When will the SIE generate an SOF interrupt?
In the EZ-USB Technical Reference Manual on page 7-22 at the bottom of the page, labeled "About USB Frames", it will confirm the answer. The SIE will generate an SOF interrupt if it detects a missing SOF packet. This is to keep ISO transfers in sync with scheduled timing.