Toshiba TLCS-900/L1 Series Manual page 42

(4) Micro DMA start vector registers
These registers assign micro DMA processing to sets which source corresponds to
DMA. The interrupt source whose micro DMA start vector value matches the vector
set in one of these registers is designated as the micro DMA start source.
When the micro DMA transfer counter value reaches zero, the micro DMA transfer
end interrupt corresponding to the channel is sent to the interrupt controller, the
micro DMA start vector register is cleared, and the micro DMA start source for the
channel is cleared. Therefore, in order for micro DMA processing to continue, the
micro DMA start vector register must be set again during processing of the micro
DMA transfer end interrupt.
If the same vector is set in the micro DMA start vector registers of more than one
channel, the lowest numbered channel takes priority.
Accordingly, if the same vector is set in the micro DMA start vector registers for two
different channels, the interrupt generated on the lower-numbered channel is
executed until micro DMA transfer is complete. If the micro DMA start vector for this
channel has not been set in the channel's micro DMA start vector register again, micro
DMA transfer for the higher-numbered channel will be commenced. (This process is
known as micro DMA chaining.)
Symbol Name Address
DMA0
DMA0V start 80H
vector
DMA1
DMA1V start 81H
vector
DMA2
DMA2V start 82H
vector
DMA3
DMA3V start 83H
vector
(5) Specification of a micro DMA burst
Specifying the micro DMA burst function causes micro DMA transfer, once started,
to continue until the value in the transfer counter register reaches zero. Setting any of
the bits in the register DMAB which correspond to a micro DMA channel (as shown
below) to 1 specifies that any micro DMA transfer on that channel will be a burst
transfer.
Symbol Name Address
DMA
89H
software
DMAR (Prohibit
request
RMW)
register
DMA
DMAB burst 8AH
register
7 6 5
DMA0V5
0
DMA1V5
0
DMA2V5
0
DMA3V5
0
7 6 5
91C829-40
4 3
DMA0V4 DMA0V3 DMA0V2
R/W
0 0
DMA0 start vector
DMA1V4 DMA1V3 DMA1V2
R/W
0 0
DMA1 start vector
DMA2V4 DMA2V3 DMA2V2
R/W
0 0
DMA2 start vector
DMA3V4 DMA3V3 DMA3V2
R/W
0 0
DMA3 start vector
4 3 2
DMAR3 DMAR2
R/W R/W
0 0
1: DMA software request
DMAB3 DMAB2
0 0
1:DMA burst request
TMP91C829
2 1 0
DMA0V1 DMA0V0
0 0 0
DMA1V1 DMA1V0
0 0 0
DMA2V1 DMA2V0
0 0 0
DMA3V1 DMA3V0
0 0 0
1 0
DMAR1 DMAR0
R/W R/W
0 0
DMAB1 DMAB0
R/W
0 0
2006-03-15