Table 23-295. eDMA peak request rate (MReq/sec)
System frequency (MHz)
Request rate
with zero wait states
Request rate
with wait states
66.6
7.4
5.8
83.3
9.2
7.2
100.0
11.1
8.7
133.3
14.8
11.6
150.0
16.6
13.0
A general formula to compute the peak request rate with overlapping requests is:
PEAKreq = freq / [ entry + (1 + read_ws) + (1 + write_ws) + exit ]
where:
Table 23-296. Peak request formula operands
Operand
Description
PEAKreq
Peak request rate
freq
System 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)
23.4.4.3 eDMA performance example
Consider a system with the following characteristics:
• Internal SRAM can be accessed with one wait-state when viewed from the system
bus data phase
• All internal peripheral bus reads require two wait-states, and internal peripheral bus
writes three wait-states viewed from the system bus data phase
• System operates at 150 MHz
For an SRAM to internal peripheral bus transfer,
PEAKreq = 150 MHz / [ 4 + (1 + 1) + (1 + 3) + 3 ] cycles = 11.5 Mreq/sec
For an internal peripheral bus to SRAM transfer,
Functional description
KV4x Reference Manual, Rev. 2, 02/2015
434
Preliminary
Freescale Semiconductor, Inc.
Содержание freescale KV4 Series
Страница 2: ...KV4x Reference Manual Rev 2 02 2015 2 Preliminary Freescale Semiconductor Inc...
Страница 60: ...KV4x Reference Manual Rev 2 02 2015 60 Preliminary Freescale Semiconductor Inc...
Страница 82: ...JTAG Controller Configuration KV4x Reference Manual Rev 2 02 2015 82 Preliminary Freescale Semiconductor Inc...
Страница 88: ...System Register file KV4x Reference Manual Rev 2 02 2015 88 Preliminary Freescale Semiconductor Inc...
Страница 128: ...Debug Security KV4x Reference Manual Rev 2 02 2015 128 Preliminary Freescale Semiconductor Inc...
Страница 138: ...Boot KV4x Reference Manual Rev 2 02 2015 138 Preliminary Freescale Semiconductor Inc...
Страница 150: ...Pinout diagrams KV4x Reference Manual Rev 2 02 2015 150 Preliminary Freescale Semiconductor Inc...
Страница 170: ...Functional description KV4x Reference Manual Rev 2 02 2015 170 Preliminary Freescale Semiconductor Inc...
Страница 212: ...Functional description KV4x Reference Manual Rev 2 02 2015 212 Preliminary Freescale Semiconductor Inc...
Страница 284: ...Functional description KV4x Reference Manual Rev 2 02 2015 284 Preliminary Freescale Semiconductor Inc...
Страница 294: ...Functional description KV4x Reference Manual Rev 2 02 2015 294 Preliminary Freescale Semiconductor Inc...
Страница 330: ...Functional description KV4x Reference Manual Rev 2 02 2015 330 Preliminary Freescale Semiconductor Inc...
Страница 450: ...Initialization application information KV4x Reference Manual Rev 2 02 2015 450 Preliminary Freescale Semiconductor Inc...
Страница 512: ...Interrupts and DMA Requests KV4x Reference Manual Rev 2 02 2015 512 Preliminary Freescale Semiconductor Inc...
Страница 520: ...Memory Map and Register Descriptions KV4x Reference Manual Rev 2 02 2015 520 Preliminary Freescale Semiconductor Inc...
Страница 580: ...Initialization Application information KV4x Reference Manual Rev 2 02 2015 580 Preliminary Freescale Semiconductor Inc...
Страница 660: ...Functional description KV4x Reference Manual Rev 2 02 2015 660 Preliminary Freescale Semiconductor Inc...
Страница 1038: ...Example configuration for chained timers KV4x Reference Manual Rev 2 02 2015 1038 Preliminary Freescale Semiconductor Inc...
Страница 1074: ...Functional description KV4x Reference Manual Rev 2 02 2015 1074 Preliminary Freescale Semiconductor Inc...
Страница 1168: ...Initialization application information KV4x Reference Manual Rev 2 02 2015 1168 Preliminary Freescale Semiconductor Inc...
Страница 1264: ...Initialization application information KV4x Reference Manual Rev 2 02 2015 1264 Preliminary Freescale Semiconductor Inc...
Страница 1336: ...Functional description KV4x Reference Manual Rev 2 02 2015 1336 Preliminary Freescale Semiconductor Inc...
Страница 1358: ...KV4x Reference Manual Rev 2 02 2015 1358 Preliminary Freescale Semiconductor Inc...