Enhanced Direct Memory Access (eDMA)
MPC5606S Microcontroller Reference Manual, Rev. 7
Freescale Semiconductor
511
•
Cycle ?+1: This cycle represents the data phase of the last destination write
•
Cycle ?+2: The DMA engine completes the execution of the inner minor loop and prepares to write
back the required TCD
n
fields into the local memory. TCD word7 is read and checked for channel
linking or scatter/gather requests.
•
Cycle ?+3: The appropriate fields in the first part of the TCD
n
are written back into the local
memory
•
Cycle ?+4: The fields in the second part of the TCD
n
are written back into the local memory. This
cycle coincides with the next channel arbitration cycle start.
•
Cycle ?+5: The next channel to be activated performs the read of the first part of its TCD from the
local memory. This is equivalent to Cycle 4 for the first channel’s service request.
Assuming zero wait states on the AHB system bus, DMA requests can be processed every 9 cycles.
Assuming an average of the access times associated with IPS-to-SRAM (4 cycles) and SRAM-to-IPS
(5 cycles), DMA requests can be processed every 11.5 cycles (4 + (4+5)
2 + 3). This is the time from
Cycle 4 to Cycle “?+5”. The resulting peak request rate, as a function of the platform frequency, is shown
in
. This metric represents millions of requests per second.
A general formula to compute the peak request rate (with overlapping requests) is:
PEAKreq = freq
[ entry + (1 + read_ws) + (1 + write_ws) + exit ]
Eqn. 15-1
where:
PEAKreq—peak request rate
freq—platform frequency
entry—channel startup (4 cycles)
read_ws—wait states seen during the system bus read data phase
write_ws—wait states seen during the system bus write data phase
exit—channel shutdown (3 cycles)
For example: consider a platform with the following characteristics:
Table 15-30. DMA peak request rate [MReq/sec]
Platform Speed
Request Rate
(zero wait state)
Request Rate
(with wait states)
66.6 MHz
7.4
5.8
83.3 MHz
9.2
7.2
100.0 MHz
11.1
8.7
133.3 MHz
14.8
11.6
150.0 MHz
16.6
13.0
Содержание MPC5602S
Страница 76: ...Overview MPC5606S Microcontroller Reference Manual Rev 7 74 Freescale Semiconductor...
Страница 82: ...Memory Map MPC5606S Microcontroller Reference Manual Rev 7 80 Freescale Semiconductor...
Страница 112: ...Signal Description MPC5606S Microcontroller Reference Manual Rev 7 110 Freescale Semiconductor...
Страница 166: ...Analog to Digital Converter ADC MPC5606S Microcontroller Reference Manual Rev 7 164 Freescale Semiconductor...
Страница 182: ...Boot Assist Module BAM MPC5606S Microcontroller Reference Manual Rev 7 180 Freescale Semiconductor...
Страница 234: ...Clock Description MPC5606S Microcontroller Reference Manual Rev 7 232 Freescale Semiconductor...
Страница 286: ...Crossbar Switch XBAR MPC5606S Microcontroller Reference Manual Rev 7 284 Freescale Semiconductor...
Страница 470: ...e200z0h Core MPC5606S Microcontroller Reference Manual Rev 7 468 Freescale Semiconductor...
Страница 524: ...Enhanced Direct Memory Access eDMA MPC5606S Microcontroller Reference Manual Rev 7 522 Freescale Semiconductor...
Страница 546: ...Error Correction Status Module ECSM MPC5606S Microcontroller Reference Manual Rev 7 544 Freescale Semiconductor...
Страница 669: ...Flash Memory MPC5606S Microcontroller Reference Manual Rev 7 Freescale Semiconductor 667...
Страница 670: ...Flash Memory MPC5606S Microcontroller Reference Manual Rev 7 668 Freescale Semiconductor...
Страница 716: ...FlexCAN MPC5606S Microcontroller Reference Manual Rev 7 714 Freescale Semiconductor...
Страница 882: ...LIN Controller LINFlex MPC5606S Microcontroller Reference Manual Rev 7 880 Freescale Semiconductor...
Страница 901: ...Memory Protection Unit MPU MPC5606S Microcontroller Reference Manual Rev 7 Freescale Semiconductor 899...
Страница 902: ...Memory Protection Unit MPU MPC5606S Microcontroller Reference Manual Rev 7 900 Freescale Semiconductor...
Страница 955: ...Mode Entry Module MC_ME MPC5606S Microcontroller Reference Manual Rev 7 Freescale Semiconductor 953...
Страница 956: ...Mode Entry Module MC_ME MPC5606S Microcontroller Reference Manual Rev 7 954 Freescale Semiconductor...
Страница 1072: ...Quad Serial Peripheral Interface QuadSPI MPC5606S Microcontroller Reference Manual Rev 7 1070 Freescale Semiconductor...
Страница 1096: ...Reset Generation Module MC_RGM MPC5606S Microcontroller Reference Manual Rev 7 1094 Freescale Semiconductor...
Страница 1106: ...Real Time Clock RTC API MPC5606S Microcontroller Reference Manual Rev 7 1104 Freescale Semiconductor...
Страница 1186: ...Stepper Stall Detect SSD MPC5606S Microcontroller Reference Manual Rev 7 1184 Freescale Semiconductor...
Страница 1213: ...System Integration Unit Lite SIUL MPC5606S Microcontroller Reference Manual Rev 7 Freescale Semiconductor 1211...
Страница 1214: ...System Integration Unit Lite SIUL MPC5606S Microcontroller Reference Manual Rev 7 1212 Freescale Semiconductor...
Страница 1238: ...Voltage Regulators and Power Supplies MPC5606S Microcontroller Reference Manual Rev 7 1236 Freescale Semiconductor...
Страница 1252: ...Wakeup Unit WKPU MPC5606S Microcontroller Reference Manual Rev 7 1250 Freescale Semiconductor...
Страница 1258: ...Registers Under Protection MPC5606S Microcontroller Reference Manual Rev 7 1256 Freescale Semiconductor...
Страница 1323: ...Register Map MPC5606S Microcontroller Reference Manual Rev 7 Freescale Semiconductor 1321...
Страница 1324: ...Register Map MPC5606S Microcontroller Reference Manual Rev 7 1322 Freescale Semiconductor...