
Enhanced Direct Memory Access Controller (eDMA)
MPC5644A Microcontroller Reference Manual, Rev. 6
186
Freescale Semiconductor
f) write_word(0x2018) Æ third iteration of the minor loop
g) read_byte(0x101C), read_byte(0x101D), read_byte(0x101E), read_byte(0x101F)
h) write_word(0x201C) Æ last iteration of the minor loop Æ major loop complete
14. eDMA engine writes: EDMA_TCD[SADDR] = 0x1000, EDMA_TCD[DADDR] = 0x2000,
EDMA_TCD[CITER] = 2 (EDMA_TCD[BITER]).
15. eDMA engine writes: EDMA_TCD[ACTIVE] = 0, EDMA_TCD[DONE] = 1,
EDMA_IRQR
n
= 1.
16. The channel retires Æ major loop complete.
The eDMA goes idle or services the next channel
.
8.5.5.3
Modulo feature
The modulo feature of the eDMA provides the ability to implement a circular data queue in which the size
of the queue is a power of two. MOD is a 5-bit bitfield for both the source and destination in the TCD and
specifies which lower address bits are allowed to increment from their original value after the
a offset calculation. All upper address bits remain the same as in the original value. A setting of 0
for this field disables the modulo feature.
shows how the transfer addresses are specified based on the setting of the MOD field. Here a
circular buffer is created where the address wraps to the original value while the 28 upper address bits
(0x1234567x) retain their original value. In this example the source address is set to 0x12345670, the
offset is set to 4 bytes and the MOD field is set to 4, allowing for a 2
4
byte (16-byte) size queue.
8.5.6
TCD status
8.5.6.1
Minor loop complete
There are two methods to test for minor loop completion when using software initiated service requests. The first method is to
read the field EDMA_TCD[CITER] and test for a change. Another method may be extracted from the sequence below. The
second method is to test the bit EDMA_TCD[START]
and
the bit EDMA_TCD[ACTIVE]. The minor loop complete condition is
indicated by both bits reading zero after EDMA_TCD[START] was written to a ‘1’. Polling the
EDMA_TCD[ACTIVE] bit may be inconclusive because the active status may be missed if the channel
execution is short in duration.
Table 8-23. Modulo feature example
Transfer number
Address
1
0x12345670
2
0x12345674
3
0x12345678
4
0x1234567C
5
0x12345670
6
0x12345674
Содержание MPC5644A
Страница 2: ...MPC5644A Microcontroller Reference Manual Rev 6 2 Freescale Semiconductor...
Страница 24: ...MPC5644A Microcontroller Reference Manual Rev 6 24 Freescale Semiconductor...
Страница 26: ...MPC5644A Microcontroller Reference Manual Rev 6 26 Freescale Semiconductor...
Страница 52: ...Introduction MPC5644A Microcontroller Reference Manual Rev 6 52 Freescale Semiconductor...
Страница 56: ...Memory Map MPC5644A Microcontroller Reference Manual Rev 6 56 Freescale Semiconductor...
Страница 130: ...Device Performance Optimization MPC5644A Microcontroller Reference Manual Rev 6 130 Freescale Semiconductor...
Страница 204: ...Multi Layer AHB Crossbar Switch XBAR MPC5644A Microcontroller Reference Manual Rev 6 204 Freescale Semiconductor...
Страница 212: ...Peripheral Bridge PBRIDGE MPC5644A Microcontroller Reference Manual Rev 6 212 Freescale Semiconductor...
Страница 558: ...System Integration Unit SIU MPC5644A Microcontroller Reference Manual Rev 6 558 Freescale Semiconductor...
Страница 582: ...Frequency modulated phase locked loop FMPLL MPC5644A Microcontroller Reference Manual Rev 6 582 Freescale Semiconductor...
Страница 766: ...Enhanced Time Processing Unit eTPU2 MPC5644A Microcontroller Reference Manual Rev 6 766 Freescale Semiconductor...
Страница 1228: ...Decimation Filter MPC5644A Microcontroller Reference Manual Rev 6 1228 Freescale Semiconductor...
Страница 1236: ...System Information Module and Trim SIM MPC5644A Microcontroller Reference Manual Rev 6 1236 Freescale Semiconductor...
Страница 1250: ...Cyclic Redundancy Checker CRC Unit MPC5644A Microcontroller Reference Manual Rev 6 1250 Freescale Semiconductor...
Страница 1336: ...Deserial Serial Peripheral Interface DSPI MPC5644A Microcontroller Reference Manual Rev 6 1336 Freescale Semiconductor...
Страница 1388: ...Enhanced Serial Communication Interface ESCI MPC5644A Microcontroller Reference Manual Rev 6 1388 Freescale Semiconductor...
Страница 1440: ...FlexCAN Module MPC5644A Microcontroller Reference Manual Rev 6 1440 Freescale Semiconductor...
Страница 1624: ...FlexRay Communication Controller FlexRay MPC5644A Microcontroller Reference Manual Rev 6 1624 Freescale Semiconductor...
Страница 1670: ...JTAG Controller JTAGC MPC5644A Microcontroller Reference Manual Rev 6 1670 Freescale Semiconductor...
Страница 1692: ...Nexus Port Controller NPC MPC5644A Microcontroller Reference Manual Rev 6 1692 Freescale Semiconductor...
Страница 1701: ...Development Trigger Semaphore DTS MPC5644A Microcontroller Reference Manual Rev 6 Freescale Semiconductor 1701...
Страница 1702: ...Development Trigger Semaphore DTS MPC5644A Microcontroller Reference Manual Rev 6 1702 Freescale Semiconductor...