Soft Start Function - Toshiba TLCS-900/L1 Series Manual

(2) Soft start function

In addition to starting the micro DMA function by interrupts, TMP91C829 includes
a micro DMA software start function that starts micro DMA on the generation of the
write cycle to the DMAR register.
Writing 1 to each bit of DMAR register causes micro DMA once (If write 0 to each
bitm micro DMA doesn't operate). At the end of transfer, the corresponding bit of the
DMAR register is automatically cleared to 0.
Only one-channel can be set for micro DMA at once. (Do not write 1 to plural bits.)
When writing again 1 to the DMAR register, check whether the bit is 0 before
writing 1. If read 1, micro DMA transfer isn't started yet.
When a burst is specified by DMAB register, data is continuously transferred until
the value in the micro DMA transfer counter is 0 after start up of the micro DMA
transfer counter doesn't change. Don't use Read-modify –write instruction to avoid
writing to other bits by mistake.
Symbol Name Address
DMA 89H
DMAR request (Prohibit
register RMW)
(3) Transfer control registers
The transfer source address and the transfer destination address are set in the
following registers. Data setting for these registers is done by an "LDC cr,r"
instruction.
7 6
Channel 0
DMAS0
DMAD0
DMAC0
DMAM0
Channel 3
DMAS3
DMAD3
DMAC3
DMAM3
8 bits
16 bits
32 bits
91C829-32
5 4 3
DMAR3
0
DMA source address register 0: Only use LSB 24 bits.
DMA destination address register 0: Only use LSB 24 bits.
DMA counter register 0: 1 to 65536.
DMA mode register 0.
DMA source address register 3.
DMA destination address register 3.
DMA counter register 3.
DMA mode register 3.
TMP91C829
2 1 0
DMAR2 DMAR1 DMAR0
R/W
0 0 0
DMA request
2006-03-15