MOTOROLA
Chapter 22. Serial Communications Controllers
22-21
Part V. The Communications Processor Module
Figure 22-12. Using CD to Control Synchronous Protocol Reception
If CD is programmed to envelope the data, it must remain asserted during frame
transmission or a CD lost error occurs. Negation of CD terminates reception. If
GSMR_H[CDS] is zero, CD must be sampled by the SCC before a CD lost error is
recognized; otherwise, the negation of CD immediately causes the CD lost condition.
If GSMR_H[CDS] is set, all CD transitions must occur while the Rx clock is low.
22.3.4.2 Asynchronous Protocols
In asynchronous protocols, RTS is asserted when SCC data is loaded into the Tx FIFO and
a falling Tx clock occurs. CD and CTS can be used to control reception and transmission
in the same manner as the synchronous protocols. The Þrst bit sent in an asynchronous
protocol is the start bit of the Þrst character. In addition, the UART protocol has an option
for CTS ßow control as described in Chapter 23, ÒSCC UART Mode.Ó
¥
If CTS is already asserted when RTS is asserted, transmission begins in two
additional bit times.
¥
If CTS is not already asserted when RTS is asserted and GSMR_H[CTSS] = 0,
transmission begins in three additional bit times.
¥
If CTS is not already asserted when RTS is asserted and GSMR_H[CTSS] = 1,
transmission begins in two additional bit times.
1. GSMR_H[CDS] = 0. CDP=0.
RCLK
First Bit of Frame Data
NOTE:
CD Sampled Low Here
RCLK
CD Sampled High Here
Last Bit of Frame Data
2. If CD is negated prior to the last bit of the receive frame, CD lost is signaled in the frame BD.
3. If CDP=1, CD lost cannot occur and CD negation has no effect on reception.
1. GSMR_H[CDS] = 1. CDP=0.
NOTE
:
2. If CD is negated prior to the last bit of the receive frame, CD lost is signaled in the frame BD.
3. If CDP=1, CD lost cannot occur and CD negation has no effect on reception.
Last Bit of Frame Data
First Bit of Frame Data
CD Assertion Immediately
Gates Reception
CD Negation Immediately
Halts Reception
RXD
(Input)
CD
(Input)
CD
(Input)
RXD
(Input)
Summary of Contents for MPC860 PowerQUICC
Page 3: ...MPC860UM AD 07 98 REV 1 MPC860 PowerQUICC ª UserÕs Manual ...
Page 36: ...xxxvi MPC860 PowerQUICC UserÕs Manual MOTOROLA CONTENTS Paragraph Number Title Page Number ...
Page 78: ...I iv MPC860 PowerQUICC UserÕs Manual MOTOROLA Part I Overview ...
Page 88: ...1 10 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part I Overview ...
Page 114: ...3 16 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part I Overview ...
Page 226: ...8 32 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part II PowerPC Microprocessor Module ...
Page 262: ...9 36 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part II PowerPC Microprocessor Module ...
Page 274: ...III iv MPC860 PowerQUICC UserÕs Manual MOTOROLA Part III Configuration ...
Page 320: ...12 12 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part III Configuration ...
Page 325: ...MOTOROLA Part IV Hardware Interface IV v Part IV Hardware Interface ...
Page 326: ...IV vi MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
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Page 632: ...21 44 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 660: ...22 28 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
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Page 998: ...37 48 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part VI Debug and Test ...
Page 1016: ...A 10 MPC860 PowerQUICC UserÕs Manual MOTOROLA Appendixes ...
Page 1024: ...B 8 MPC860 PowerQUICC UserÕs Manual MOTOROLA Appendixes ...
Page 1030: ...C 6 MPC860 PowerQUICC UserÕs Manual MOTOROLA Appendixes ...
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