
iiBusModuLes:high-sPeeddMa(hsdMa)
ii-1-46
ePson
s1C33L17teChniCaLManuaL
ii.1.10Precautions
When setting the transfer conditions, always make sure the DMA controller is inactive (HSx_EN (D0/0x30112C
+ 0x10x) = 0).
hsx_en:Ch.xEnableBitintheHSDMACh.xEnableRegister(D0/0x30112C+0x10x)
After an initial reset, the cause-of-interrupt flag (FHDMx (Dx/0x300281)) becomes indeterminate. Always be
sure to reset the flag to prevent interrupts or IDMA requests from being generated inadvertently.
FhdMx:HSDMACh.xCause-of-InterruptFlagintheDMAInterruptCauseFlagRegister(Dx/0x300281)
To prevent an interrupt from being generated repeatedly for the same source, be sure to reset the cause-of-inter-
rupt flag before setting up the PSR again or executing the reti instruction.
HSDMA is given higher priority over IDMA (intelligent DMA) and the CPU. However, since HSDMA and
IDMA share the same circuit, HSDMA cannot gain the bus ownership while an IDMA transfer is under way.
Requests for HSDMA invocation that have occurred during an IDMA transfer are kept pending until the IDMA
transfer is completed.
A request for IDMA invocation or an interrupt request that has occurred during a HSDMA transfer are accepted
after completion of the HSDMA transfer.
In dual-address mode, A0RAM (area 0), Specific ROM (area 1), and IVRAM (area 0) cannot be specified as the
source or destination for DMA transfer. While IVRAM (area 3), DST RAM (area 3) and the internal peripheral
I/O registers (area 6) can be used for dual-address transfer.
In single-address mode, A0RAM (area 0), Specific ROM (area 1), area 2, IVRAM (area 0 or area 3), DST RAM
(area 3) and the internal peripheral I/O registers (area 6) cannot be used for DMA transfer.
Single-address mode does not allow data transfer between memory devices. An external logic circuit is required
to perform single-address transfer between memory devices.
Single-address mode does not support the external memory area that is configured for SDRAM.
Be sure to disable the HSDMA before setting the chip in SLEEP mode (executing the slp instruction). HALT
mode can be set even if the HSDMA is enabled.