Serial Communications Controllers (SCCs)
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
Freescale Semiconductor 20-21
20.3.6 Digital Phase-Locked Loop (DPLL) Operation

Each SCC channel includes a digital phase-locked loop (DPLL) for recovering clock information from a

received data stream. For applications that provide a direct clock source to the SCC, the DPLL can be

bypassed by selecting 1x mode for GSMR_L[RDCR, TDCR]. If the DPLL is bypassed, only NRZ or

NRZI encodings are available. The DPLL must not be used when an SCC is programmed to Ethernet and

is optional for other protocols. Figure20-13 shows the DPLL receiver block; Figure 20-14 shows the

transmitter block diagram.

Figure 20-13. DPLL Receiver Block Diagram

DPLL
HSRCLK
RXD
RINV
TSNC
EDGE
RDCR
RENC
Receiver
Carrier SNC
Decoded Data
Hunting
Noise
0
S
Recovered Clock
HSRCLK RCLK
1
1x Mode
0
S
SCCR Data
1
1x Mode
D
CLK
Q
HSRCLK
RXD
RINV
RENC = NRZI