DM163025 Microchip Technology, DM163025 Datasheet - Page 14

• Manufacturer Part Number: DM163025
• Description: PIC DEM FULL SPEED USB DEMO BRD
• Manufacturer: Microchip Technology

Specifications of DM163025

• Main Purpose: Interface, USB 2.0 Host/Controller
• Embedded: Yes, MCU, 8-Bit
• Utilized Ic / Part: PIC18F2455/2550/4455/4550
• Primary Attributes: Full Speed (12Mbps)
• Secondary Attributes: MPLAB ICE 2000/4000 Emulator Interface, Temp Sensor, Expansion and PICtail Headers
• Processor To Be Evaluated: PIC18F4550
• Interface Type: RS-232, USB
• Silicon Manufacturer: Microchip
• Core Architecture: PIC
• Core Sub-architecture: PIC18
• Silicon Core Number: PIC18F
• Silicon Family Name: PIC18F4xxx
• Kit Contents: Demo Board, Cables, CD & Documents
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant
• Other names: Q2086254

DS51526B-page 10
™
1.4.1
The USB module of the PIC18F4550 requires a specific clock frequency input to oper-
ate correctly; specifically, 48 MHz is required when operating in Full-Speed mode, or
6 MHz when operating in Low-Speed mode. The PICDEM FS USB board uses a
20 MHz crystal oscillator as an external clock, and derives the necessary internal clock
frequencies from the 96 MHz PLL module. The clock configuration used on the
demonstration board is shown in Figure 1-2. A detailed explanation of how to set up the
clock configuration is explained in Chapter 2.0 of the PIC18F4550 device data sheet
(DS39632).
The PICDEM FS USB board is configured to run in Full-Speed USB mode, generating
an internal system clock of 48 MHz (equivalent to 12 MIPS) from the external 20 MHz
crystal.
FIGURE 1-2:
1.4.2
The PICDEM FS USB demonstration board operates at 5V. Power can be drawn
directly from the USB bus or from an external power supply. There are no jumpers to
select which power source to use. Instead, the power circuitry automatically selects the
external power source when both power sources are available. Two LEDs, D7 and D8,
are used to indicate the active power source. D7 indicates that the board is operating
in Bus Power mode; D8 indicates Self-Power mode (i.e., an external power supply).
Like most USB peripherals, the PICDEM FS USB board can be powered from the 5V
available from the USB cable. A minimum of 100 mA is always available on the bus for
a device; a maximum of 500 mA can be requested and used if available.
A barrel-type power supply connector (2.5 mm diameter) is also provided to run the
board from a 9-18 V
every example included will run from USB bus power.
Y1
Note:
Oscillator and Operating Frequency
Power
There are no power conditions that will cause both D7 and D8 to light at the
same time.
Oscillator
Primary
DC
PIC18F4550 CLOCK SETUP FOR PICDEM™ FS USB
20 MHz
power supply. A transformer is not supplied in the kit because
(requires 4 MHz
Input Prescaler
PIC18F4550 Oscillator Block
(configured as
Configurable
96 MHz PLL
divide-by-5)
Divide-by-2
input)
Fixed
4 MHz
96 MHz
96 MHz
Clock Postscaler
(configured as
Configurable
divide-by-2)
© 2008 Microchip Technology Inc.
48 MHz
48 MHz
USB
Clock
CPU and
Peripherals
Clock