21-22
MPC8260 PowerQUICC II UserÕs Manual
MOTOROLA
Part IV. Communications Processor Module
Figure 21-15. Delayed RTS Mode
21.14.5 Using the Time-Slot Assigner (TSA)
HDLC bus controllers can be used with a time-division multiplexed transmission line and
a local bus, as shown in Figure 21-16. Local stations use time slots to communicate over
the TDM transmission line; stations that share a time slot use the HDLC bus protocol to
control access to the local bus.
Figure 21-16. HDLC Bus TDM Transmission Line Configuration
The local SCCs in HDLC bus mode communicate only with the transmission line and not
with each other. The SCCs use the TSA of the serial interface, receiving and sending data
over L1TXD
x
and L1RXD
x
. Because collisions are still detected from the individual SCC
CTS pin, it must be conÞgured to connect to the chosen SCC. Because the SCC only
receives clocks during its time slot, CTS is sampled only during the Tx clock edges of the
particular SCC time slot.
TCLK
RTS active for
only 2 bit times
TXD
CTS
RTS
1st Bit
2nd Bit
3rd Bit
Collision
Local HDLC Bus
HDLC Bus
Controller
L1RXD
CTS
L1TXD
B
HDLC Bus
Controller
L1RXD
CTS
L1TXD
D
+ 5 V
R
NOTES:
1. All TXD pins of slave devices should be configured to open-drain in the port C parallel I/O port.
2. The TSA in the SI of each station is used to configure the preferred time slot.
Tx
Rx
Line Driver
HDLC Bus
Controller
L1RXD
CTS
L1TXD
C
HDLC Bus
Controller
L1RXD
CTS
L1TXD
A
Stations share time-slot n
Stations share time-slot m
3. The choice of the number of stations to share a time slot is user-defined. It is two in this example.
Summary of Contents for MPC8260 PowerQUICC II
Page 1: ...MPC8260UM D 4 1999 Rev 0 MPC8260 PowerQUICC II UserÕs Manual ª ª ...
Page 66: ...lxvi MPC8260 PowerQUICC II UserÕs Manual MOTOROLA ...
Page 88: ...1 18 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part I Overview ...
Page 120: ...2 32 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part I Overview ...
Page 138: ...Part II iv MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part II Configuration and Reset ...
Page 184: ...4 46 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part II ConÞguration and Reset ...
Page 202: ...Part III vi MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part III The Hardware Interface ...
Page 266: ...8 34 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part III The Hardware Interface ...
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Page 430: ...Part IV viii MOTOROLA Part IV Communications Processor Module ...
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Page 980: ...A 4 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Appendixes ...
Page 1002: ...Index 22 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA INDEX ...
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