An interface detecting circuit and interface detecting method are
provided, whereby operations can be carried out depending on peripheral
devices connected to USB terminals, and whereby the system can be
simplified and software load can be reduced. A pull-down resistor is
connected to an ID terminal of a Mini-A receptacle of a peripheral
device, the voltage generated by the pull-down resistor, which is pulled
down by the ID terminal of the Mini-A receptacle of the peripheral
device, and a pull-up resistor, which is pulled up by the ID terminal of
a Mini-B receptacle of a device, is detected in an analog fashion, using
a detecting section comprised of comparators, and, via a logic section, a
logic output is subjected to noise cancellation in a filter section and
is memorized in a register section. The operations of other devices are
determined according to the states memorized in the register section.