
3. Enable error interrupts in the EEI register if so desired.
4. Write the 32-byte TCD for each channel that may request service.
5. Enable any hardware service requests via the ERQ register.
6. Request channel service via either:
• Software: setting the TCDn_CSR[START]
• Hardware: slave device asserting its eDMA peripheral request signal
After any channel requests service, a channel is selected for execution based on the
arbitration and priority levels written into the programmer's model. The eDMA engine
reads the entire TCD, including the TCD control and status fields, as shown in the
following table, for the selected channel into its internal address path module.
As the TCD is read, the first transfer is initiated on the internal bus, unless a
configuration error is detected. Transfers from the source, as defined by TCDn_SADDR,
to the destination, as defined by TCDn_DADDR, continue until the number of bytes
specified by TCDn_NBYTES are transferred.
When the transfer is complete, the eDMA engine's local TCDn_SADDR,
TCDn_DADDR, and TCDn_CITER are written back to the main TCD memory and any
minor loop channel linking is performed, if enabled. If the major loop is exhausted,
further post processing executes, such as interrupts, major loop channel linking, and
scatter/gather operations, if enabled.
Table 20-8. TCD Control and Status fields
TCDn_CSR field
name
Description
START
Control bit to start channel explicitly when using a software initiated DMA service (Automatically
cleared by hardware)
ACTIVE
Status bit indicating the channel is currently in execution
DONE
Status bit indicating major loop completion (cleared by software when using a software initiated
DMA service)
D_REQ
Control bit to disable DMA request at end of major loop completion when using a hardware initiated
DMA service
BWC
Control bits for throttling bandwidth control of a channel
E_SG
Control bit to enable scatter-gather feature
INT_HALF
Control bit to enable interrupt when major loop is half complete
INT_MAJ
Control bit to enable interrupt when major loop completes
The following figure shows how each DMA request initiates one minor-loop transfer, or
iteration, without CPU intervention. DMA arbitration can occur after each minor loop,
and one level of minor loop DMA preemption is allowed. The number of minor loops in
a major loop is specified by the beginning iteration count (BITER).
Initialization/application information
K32 L2A Reference Manual, Rev. 2, 01/2020
466
NXP Semiconductors
Содержание K32 L2A Series
Страница 2: ...K32 L2A Reference Manual Rev 2 01 2020 2 NXP Semiconductors...
Страница 42: ...K32 L2A Reference Manual Rev 2 01 2020 42 NXP Semiconductors...
Страница 122: ...Flash Memory Clock K32 L2A Reference Manual Rev 2 01 2020 122 NXP Semiconductors...
Страница 146: ...Module operation in low power modes K32 L2A Reference Manual Rev 2 01 2020 146 NXP Semiconductors...
Страница 158: ...Debug and security K32 L2A Reference Manual Rev 2 01 2020 158 NXP Semiconductors...
Страница 174: ...Module Signal Description Tables K32 L2A Reference Manual Rev 2 01 2020 174 NXP Semiconductors...
Страница 246: ...Application information K32 L2A Reference Manual Rev 2 01 2020 246 NXP Semiconductors...
Страница 322: ...Kinetis Bootloader Status Error Codes K32 L2A Reference Manual Rev 2 01 2020 322 NXP Semiconductors...
Страница 344: ...Application initialization information K32 L2A Reference Manual Rev 2 01 2020 344 NXP Semiconductors...
Страница 374: ...CMP Trigger Mode K32 L2A Reference Manual Rev 2 01 2020 374 NXP Semiconductors...
Страница 384: ...Functional description K32 L2A Reference Manual Rev 2 01 2020 384 NXP Semiconductors...
Страница 592: ...Application Information K32 L2A Reference Manual Rev 2 01 2020 592 NXP Semiconductors...
Страница 602: ...Initialization and application information K32 L2A Reference Manual Rev 2 01 2020 602 NXP Semiconductors...
Страница 656: ...Functional Description K32 L2A Reference Manual Rev 2 01 2020 656 NXP Semiconductors...
Страница 664: ...Functional Description K32 L2A Reference Manual Rev 2 01 2020 664 NXP Semiconductors...
Страница 744: ...Functional description K32 L2A Reference Manual Rev 2 01 2020 744 NXP Semiconductors...
Страница 762: ...Functional description K32 L2A Reference Manual Rev 2 01 2020 762 NXP Semiconductors...
Страница 806: ...Functional description K32 L2A Reference Manual Rev 2 01 2020 806 NXP Semiconductors...
Страница 868: ...Integer square root K32 L2A Reference Manual Rev 2 01 2020 868 NXP Semiconductors...
Страница 976: ...Functional description K32 L2A Reference Manual Rev 2 01 2020 976 NXP Semiconductors...
Страница 1012: ...Functional description K32 L2A Reference Manual Rev 2 01 2020 1012 NXP Semiconductors...
Страница 1094: ...Functional description K32 L2A Reference Manual Rev 2 01 2020 1094 NXP Semiconductors...
Страница 1132: ...Functional description K32 L2A Reference Manual Rev 2 01 2020 1132 NXP Semiconductors...
Страница 1182: ...Functional description K32 L2A Reference Manual Rev 2 01 2020 1182 NXP Semiconductors...
Страница 1290: ...Functional description K32 L2A Reference Manual Rev 2 01 2020 1290 NXP Semiconductors...
Страница 1344: ...USB Voltage Regulator Module Signal Descriptions K32 L2A Reference Manual Rev 2 01 2020 1344 NXP Semiconductors...
Страница 1356: ...Initialization Application Information K32 L2A Reference Manual Rev 2 01 2020 1356 NXP Semiconductors...