PIC18F44J50-I Datasheet, PDF (357/562 Pages) Microchip Technology – 28/44-Pin, Low-Power, High-Performance USB Microcontrollers

PIC18F46J50 FAMILY
22.0 UNIVERSAL SERIAL BUS
(USB)
This section describes the details of the USB peripheral.
Because of the very specific nature of the module,
knowledge of USB is expected. Some high-level USB
information is provided in Section 22.9 “Overview of
USB” only for application design reference. Designers
are encouraged to refer to the official specification
published by the USB Implementers Forum (USB-IF) for
the latest information. “USB Specification Revision 2.0”
is the most current specification at the time of publication
of this document.
22.1 Overview of the USB Peripheral
PIC18F46J50 family devices contain a full-speed and
low-speed, compatible USB Serial Interface Engine
(SIE) that allows fast communication between any USB
host and the PIC^® MCU. The SIE can be interfaced
directly to the USB, utilizing the internal transceiver.
Some special hardware features have been included to
improve performance. Dual access port memory in the
device’s data memory space (USB RAM) has been
supplied to share direct memory access between the
microcontroller core and the SIE. Buffer descriptors are
also provided, allowing users to freely program end-
point memory usage within the USB RAM space.
Figure 22-1 provides a general overview of the USB
peripheral and its features.
FIGURE 22-1:
USB PERIPHERAL AND OPTIONS
PIC18F46J50 Family
USB Clock from the
Oscillator Module
FSEN
UPUEN
UTRDIS
P
P
Internal Pull-ups
Transceiver
FS
VUSB
Optional
External
Pull-ups⁽¹⁾
(Full
Speed)
D+
D-
External 3.3V
Supply
(Low
Speed)
USB Bus
USB Control and
Configuration
USB
SIE
3.8-Kbyte
USB RAM
Note 1: The internal pull-up resistors should be disabled (UPUEN = 0) if external pull-up resistors are used.
 2011 Microchip Technology Inc.
DS39931D-page 357