What is added to the MAX3421E when operating as a USB peripheral that makes it different than the MAX3420E?
• The MAX3421E adds four general-purpose input pins, and four general-purpose output pins. This brings the GPIO total to eight in, eight out. • The MAX3421E adds interrupt requests for the eight general-purpose input pins. Each pin has an interrupt enable bit and edge polarity bit associated with it. • The MAX3421E has a bit called SEPIRQ. This bit allows the GPX pin to serve as a second interrupt output pin (in addition to INT), which is active only for the GPIN interrupts. • The MAX3421E can program the time at which the INT pin deasserts and reasserts in edge interrupt mode when one interrupt is cleared and another is pending. The MAX3420E uses a fixed time of 10.6µs for this interval.
