Motorola MPC8260 User Manual

32-4

MOTOROLA

Figure 32-2 shows an example of synchronization using external signals.

MPC8260(A) and MPC8260(B) exchange transparent frames and synchronize each other
using RTS and CD. However, CTS is not required because transmission begins at any time.
Thus, RTS is connected directly to the other MPC8260Õs CD. GFMR[SYNL] is not used
and transmission and reception from each MPC8260 are independent.

RXD

CD

CLKx

TXD

RTS

CD

RXD

BRGOx

RTS

TXD

CLKx

BRGOx

BRGOx

Last Bit of Frame Data

First Bit of Frame Data

(Output is CLKx Input)

TXD

(Output is RXD Input)

RTS

(Output is CD Input)

or CRC

TxBD[L] = 1 Causes Negation of RTS

CD Lost Condition Terminates Reception of Frame

Notes:

1.  Each MPC8260 generates its own transmit clocks. If the transmit and receive clocks are the same, one can 

generate transmit and receive clocks for the other MPC8260. For example, CLKx on MPC8260 (B) could be used to 
clock the transmitter and receiver.

2. CTS should be conÞgured as always asserted in the parallel I/O port or connected to ground externally.
3.  The required GSMR conÞgurations are DIAG= 00, CTSS=1, CTSP is a donÕt care, CDS=1, CDP=0, TTX=1, and 

TRX=1. REVD and TCRC are application-dependent.

4.  The transparent frame contains a CRC if TxBD[TC] is set.