Dma Transfer - Toshiba TMPR4925 Manual

8.3.9

DMA Transfer

The sequence of DMA transfer that uses only the DMA Channel Register is as follows below.
(1) Select DMA request signal
To perform external I/O or internal I/O DMA, set the DMA Request Select field of the DMA
Request Control Register (DRQCTR. DMAREQ). For external I/O DMA, also program the
function of the shared pin through the DMA Select field of the Pin Configuration Register
(PCFG.SELDMA).
(2) Set the Master Enable bit
Set the Master Enable bit (DMMCR.MSTEN) of the DMA Master Control Register.
(3) Set the Address Register and Count Register
Set the five following register values.
•
DMA Source Address Register (DMSARn)
•
DMA Destination Address Register (DMDARn)
•
DMA Count Register (DMCNTRn)
•
DMA Source Address Increment Register (DMSAIRn)
•
DMA Destination Address Increment Register (DMDAIRn)
(4) Set Chain Address Register
Set "0" to the DMA Chain Address Register (DMCHARn).
(5) Clear the DMA Channel Status Register (DMCSRn)
Clear when status from the previous DMA transfer remains.
(6) Set the DMA Channel Control Register (DMCCRn)
(7) Initiate DMA transfer
DMA transfer is started by setting the Transfer Active bit (XFACT) of the DMA Channel Control
Register.
(8) Signal completion
When DMA data transfer ends normally, set the Normal Transfer Complete bit (NTRNFC) of the
DMA Channel Status Register (DMCSRn). An interrupt is signalled if the Transfer Complete
Interrupt Enable bit (INTENT) of the DMA Channel Control Register (DMCCRn) is set.
If an error is detected during DMA transfer, the error cause is recorded in the lower four bits of the
DMA Channel Status Register and the transfer is interrupted. If the Error Interrupt Enable bit
(INTENE) of the DMA Channel Control Register is set, then the interrupt is signaled.
Chapter 8 DMA Controller
8-15