mpc823rg Freescale Semiconductor, Inc, mpc823rg Datasheet - Page 803

• Manufacturer Part Number: mpc823rg
• Description: Mpc823 Powerquicc Integrated Communications Processor For Portable Systems
• Manufacturer: Freescale Semiconductor, Inc

The USB controller accepts a reference clock that is four times the USB bit rate. This clock
is programmed in the R1CS field of the serial interface clock register (SICR) and used by
the DPLL circuitry to recover the bit rate clock. Refer to Section 16.7.5.3 Serial Interface
Clock Route Register for more information.
A system clock frequency of at least 40MHz is necessary for operating the USB controller
in high-speed mode using an externally supplied 48MHz reference clock. Alternatively, a
system clock frequency of an exact integral multiple of 48MHz is necessary for operating
the USB controller in high-speed mode using an internal BRG to supply the 48MHz
reference clock.
Note: The MPC823 can run at different frequencies, but the USB reference clock must
USBTXN, USBTXP
UBRXP, USBRXN
PIN SYMBOL
USBRXD
USBOE
be four times the USB bit rate. The reference clock must be 48MHz for a 12Mb
full-speed transfer or 6MHz for a 1.5Mb low-speed transfer.
Freescale Semiconductor, Inc.
For More Information On This Product,
Table 16-31. USB Pin Functionality
MPC823 REFERENCE MANUAL
Go to: www.freescale.com
I/O
O
O
I
I
Outputs from the USB transmitter, inputs to the
Receive Data. Input the USB receiver from the
Gated version of D+ and D-. Used to detect
single-ended zero, and interconnect speed.
transceiver to transmit data on the bus.
Output Enable. Active low, enables the
TP
RP
0
0
1
1
0
1
0
1
differential line receiver.
differential driver.
RN
TN
0
1
0
1
0
0
1
1
FUNCTION
Communication Processor Module
single ended “0”
single ended “0”
low speed
full speed
RESULT
RESULT
logic “0”
logic “1”
n/a
n/a
16-351