Memory Controller
MPC885 PowerQUICC Family Reference Manual, Rev. 2
15-20
Freescale Semiconductor
15.5.1.1
Chip-Select Assertion Timing
The banks selected by the GPCM support an option to output CS at different timings with respect to the
external address bus. Depending on the value of the ACS field (plus an additional cycle if TRLX = 1), CS
can be output as follows
•
Simultaneous with the external address
•
One quarter of a clock cycle later
•
One half of a clock cycle later
Figure 15-16
shows a basic connection between the MPC885 and an external peripheral device. Here, CS
(the strobe output for the memory access) is connected directly to CE of the memory device and R/W is
connected to the respective R/W in the peripheral device.
1
Read
x
x
00
0
3/4*Clk
x
x
1/4*Clk
x
2+2*SCY
10
1+1/4*Clk 1+3/4*Clk
3+2*SCY
11
1+1/2*Clk
Write
0
00
0
x
3/4*Clk
-1/4*Clk
1/4*Clk
2+2*SCY
10
1+1/4*Clk
1+3/4*Clk
3/4*Clk
3+2*SCY
11
1+1/2*Clk
00
1
00
0
3/4*Clk
-1/4*Clk
1+1/2*Clk
10
1+1/4*Clk
1+3/4*Clk
3/4*Clk
1+1/2*Clk
4+2*SCY
11
1+1/2*Clk
01
00
0
3/4*Clk
-1/4*Clk
1/4*Clk
1+3/8*Clk
3+2*SCY
10
1+1/4*Clk
1+3/4*Clk
3/4*Clk
1+3/8*Clk
4+2*SCY
11
1+1/2*Clk
1
SCY is the number of wait cycles from the option register.
Table 15-11. GPCM Strobe Signal Behavior (continued)
Configuration
Signal Behavior
OR
x
[TRLX]
Access
SCCR
[EBDF]
OR
x
[CSNT]
OR
x
[ACS]
Address
to CS
Asserted
Address
to OE
Asserted
Address
to WE
Asserted
Data to
WE
Asserted
CS
Negated to
Address/
Data Invalid
WE
Negated to
Address/
Data Invalid
Total
Cycles
Содержание PowerQUICC MPC870
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Страница 738: ...SCC Asynchronous HDLC Mode and IrDA MPC885 PowerQUICC Family Reference Manual Rev 2 25 16 Freescale Semiconductor ...
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 ...
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Страница 882: ...Universal Serial Bus USB MPC885 PowerQUICC Family Reference Manual Rev 2 31 34 Freescale Semiconductor ...
Страница 944: ...Parallel I O Ports MPC885 PowerQUICC Family Reference Manual Rev 2 34 26 Freescale Semiconductor ...
Страница 956: ...CPM Interrupt Controller MPC885 PowerQUICC Family Reference Manual Rev 2 35 12 Freescale Semiconductor ...
Страница 1004: ...Buffer Descriptors and Connection Tables MPC885 PowerQUICC Family Reference Manual Rev 2 37 30 Freescale Semiconductor ...
Страница 1022: ...ATM Parameter RAM MPC885 PowerQUICC Family Reference Manual Rev 2 38 18 Freescale Semiconductor ...
Страница 1068: ...ATM Pace Control MPC885 PowerQUICC Family Reference Manual Rev 2 40 22 Freescale Semiconductor ...
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 ...
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