
1. Switch to Round-Robin Channel Arbitration mode, change the channel priorities,
then switch back to Fixed Arbitration mode,
2. Disable all the channels, change the channel priorities, then enable the appropriate
channels.
22.5.7.2 Dynamic channel linking
Dynamic channel linking is the process of setting the TCD.major.e_link bit during
channel execution (see the diagram in
). This bit is read from the TCD
local memory at the end of channel execution, thus allowing the user to enable the feature
during channel execution.
Because the user is allowed to change the configuration during execution, a coherency
model is needed. Consider the scenario where the user attempts to execute a dynamic
channel link by enabling the TCD.major.e_link bit at the same time the eDMA engine is
retiring the channel. The TCD.major.e_link would be set in the programmer’s model, but
it would be unclear whether the actual link was made before the channel retired.
The following coherency model is recommended when executing a dynamic channel link
request.
1. Write 1 to the TCD.major.e_link bit.
2. Read back the TCD.major.e_link bit.
3. Test the TCD.major.e_link request status:
• If TCD.major.e_link = 1, the dynamic link attempt was successful.
• If TCD.major.e_link = 0, the attempted dynamic link did not succeed (the
channel was already retiring).
For this request, the TCD local memory controller forces the TCD.major.e_link bit to
zero on any writes to a channel’s TCD.word7 after that channel’s TCD.done bit is set,
indicating the major loop is complete.
NOTE
The user must clear the TCD.done bit before writing the
TCD.major.e_link bit. The TCD.done bit is cleared
automatically by the eDMA engine after a channel begins
execution.
Initialization/application information
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
504
NXP Semiconductors
Содержание K22F series
Страница 2: ...K22F Sub Family Reference Manual Rev 4 08 2016 2 NXP Semiconductors...
Страница 150: ...Private Peripheral Bus PPB memory map K22F Sub Family Reference Manual Rev 4 08 2016 150 NXP Semiconductors...
Страница 168: ...Module clocks K22F Sub Family Reference Manual Rev 4 08 2016 168 NXP Semiconductors...
Страница 198: ...Security Interactions with other Modules K22F Sub Family Reference Manual Rev 4 08 2016 198 NXP Semiconductors...
Страница 258: ...Functional description K22F Sub Family Reference Manual Rev 4 08 2016 258 NXP Semiconductors...
Страница 292: ...Functional description K22F Sub Family Reference Manual Rev 4 08 2016 292 NXP Semiconductors...
Страница 398: ...Functional description K22F Sub Family Reference Manual Rev 4 08 2016 398 NXP Semiconductors...
Страница 628: ...Initialization and application information K22F Sub Family Reference Manual Rev 4 08 2016 628 NXP Semiconductors...
Страница 740: ...Initialization Application Information K22F Sub Family Reference Manual Rev 4 08 2016 740 NXP Semiconductors...
Страница 750: ...Functional description K22F Sub Family Reference Manual Rev 4 08 2016 750 NXP Semiconductors...
Страница 816: ...Application information K22F Sub Family Reference Manual Rev 4 08 2016 816 NXP Semiconductors...
Страница 866: ...Initialization Application Information K22F Sub Family Reference Manual Rev 4 08 2016 866 NXP Semiconductors...
Страница 890: ...Application information K22F Sub Family Reference Manual Rev 4 08 2016 890 NXP Semiconductors...
Страница 1028: ...Initialization Procedure K22F Sub Family Reference Manual Rev 4 08 2016 1028 NXP Semiconductors...
Страница 1040: ...Example configuration for chained timers K22F Sub Family Reference Manual Rev 4 08 2016 1040 NXP Semiconductors...
Страница 1118: ...Device mode IRC48 operation K22F Sub Family Reference Manual Rev 4 08 2016 1118 NXP Semiconductors...
Страница 1122: ...USB Voltage Regulator Module Signal Descriptions K22F Sub Family Reference Manual Rev 4 08 2016 1122 NXP Semiconductors...
Страница 1180: ...Initialization application information K22F Sub Family Reference Manual Rev 4 08 2016 1180 NXP Semiconductors...
Страница 1302: ...Application information K22F Sub Family Reference Manual Rev 4 08 2016 1302 NXP Semiconductors...
Страница 1374: ...Functional description K22F Sub Family Reference Manual Rev 4 08 2016 1374 NXP Semiconductors...