SCC Transparent Mode
MPC885 PowerQUICC Family Reference Manual, Rev. 2
28-4
Freescale Semiconductor
28.3.1.2.1
External Synchronization Example
Figure 28-1
shows synchronization using external signals.
Figure 28-1. Sending Transparent Frames between MPC885
MPC885(A) and MPC885(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 MPC885 CD pin. GSMR_H[RSYN] is not used and transmission and reception from each
MPC885 are independent.
28.3.1.3
Transparent Mode without Explicit Synchronization
If there is no need to synchronize the transparent controller at a specific point, the user can ‘fake’
synchronization in one of the following ways:
•
Tie a parallel I/O pin to the CTS and CD lines. Then, after enabling the receiver and transmitter,
provide a falling edge by manipulating the I/O pin in software.
•
Enable the receiver and transmitter for the SCC in loop-back mode and then change
GSMR_L[DIAG] to 0b00 while the transmitter and receiver and enabled.
RXD
CD
CLK
x
TXD
RTS
CD
RXD
BRGO
x
RTS
TXD
CLK
x
BRGO
x
BRGO
x
Last Bit of Frame Data
First Bit of Frame Data
(Output is CLK
x
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
MPC885 (A)
MPC885 (B)
Note:
1
Each MPC885 generates its own transmit clocks. If the transmit and receive clocks are the same, one MPC885 can
generate transmit and receive clocks for the other MPC885. For example, CLK
x on MPC885(B) could be used to
clock the transmitter and receiver.
2
RTS should be configured as always asserted in the Port C parallel I/O or connected to ground externally.
3
The required GSMR configurations are DIAG= 00, CTSS=1, CTSP is a “don’t 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.
Содержание PowerQUICC MPC870
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Страница 98: ...MPC885 PowerQUICC Family Reference Manual Rev 2 I 4 Freescale Semiconductor ...
Страница 118: ...MPC885 Overview MPC885 PowerQUICC Family Reference Manual Rev 2 1 20 Freescale Semiconductor ...
Страница 158: ...The MPC8xx Core MPC885 PowerQUICC Family Reference Manual Rev 2 3 18 Freescale Semiconductor ...
Страница 192: ...MPC885 Instruction Set MPC885 PowerQUICC Family Reference Manual Rev 2 5 22 Freescale Semiconductor ...
Страница 242: ...Instruction and Data Caches MPC885 PowerQUICC Family Reference Manual Rev 2 7 30 Freescale Semiconductor ...
Страница 288: ...MPC885 PowerQUICC Family Reference Manual Rev 2 III 4 Freescale Semiconductor ...
Страница 416: ...External Bus Interface MPC885 PowerQUICC Family Reference Manual Rev 2 13 42 Freescale Semiconductor ...
Страница 440: ...Clocks and Power Control MPC885 PowerQUICC Family Reference Manual Rev 2 14 24 Freescale Semiconductor ...
Страница 554: ...MPC885 PowerQUICC Family Reference Manual Rev 2 V 6 Freescale Semiconductor ...
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Страница 780: ...SCC Ethernet Mode MPC885 PowerQUICC Family Reference Manual Rev 2 27 24 Freescale Semiconductor ...
Страница 794: ...SCC Transparent Mode MPC885 PowerQUICC Family Reference Manual Rev 2 28 14 Freescale Semiconductor ...
Страница 848: ...Serial Peripheral Interface SPI MPC885 PowerQUICC Family Reference Manual Rev 2 30 18 Freescale Semiconductor ...
Страница 882: ...Universal Serial Bus USB MPC885 PowerQUICC Family Reference Manual Rev 2 31 34 Freescale Semiconductor ...
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Страница 1090: ...UTOPIA Interface MPC885 PowerQUICC Family Reference Manual Rev 2 43 8 Freescale Semiconductor ...
Страница 1120: ...AAL2 Implementation MPC885 PowerQUICC Family Reference Manual Rev 2 44 30 Freescale Semiconductor ...
Страница 1162: ...Fast Ethernet Controller FEC MPC885 PowerQUICC Family Reference Manual Rev 2 45 40 Freescale Semiconductor ...
Страница 1172: ...SEC Lite Overview MPC885 PowerQUICC Family Reference Manual Rev 2 46 8 Freescale Semiconductor ...
Страница 1176: ...SEC Lite Address Map MPC885 PowerQUICC Family Reference Manual Rev 2 47 4 Freescale Semiconductor ...
Страница 1214: ...SEC Lite Execution Units MPC885 PowerQUICC Family Reference Manual Rev 2 48 38 Freescale Semiconductor ...
Страница 1312: ...Byte Ordering MPC885 PowerQUICC Family Reference Manual Rev 2 A 8 Freescale Semiconductor ...
Страница 1313: ...MPC885 PowerQUICC Family Reference Manual Rev 2 Freescale Semiconductor B 1 Appendix B Serial Communications Performance TBD ...
Страница 1314: ...Serial Communications Performance MPC885 PowerQUICC Family Reference Manual Rev 2 B 2 Freescale Semiconductor ...
Страница 1320: ...Register Quick Reference Guide MPC885 PowerQUICC Family Reference Manual Rev 2 C 6 Freescale Semiconductor ...
Страница 1336: ...MPC885 PowerQUICC Family Reference Manual Rev 2 D 16 Freescale Semiconductor ...
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Страница 1386: ...Revision History MPC885 PowerQUICC Family Reference Manual Rev 2 I 2 Freescale Semiconductor ...