TMP91C824
91C824-42
(2) Soft
start
function
In addition to starting the micro DMA function by interrupts, TMP91C824 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. At the end of transfer, the
corresponding bit of the DMAR register is automatically cleared to “0”.
Only one-channel can be set once for micro DMA. (Do not write “1” to plural bits.)
When writing again “1” to the DMAR register, check whether the bit is “0” before writing “1”.
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.
Symbol
NAME
Address
7 6 5 4 3 2 1 0
DMA
Request
DMAR3
DMAR2
DMAR1
DMAR0
R/W
DMAR
DMA
Request
Register
89h
(no RMW)
0
0
0
0
(3) Transfer control registers
The transfer source address and the transfer destination address are set in the following registers
in CPU. Data setting for these registers is done by an “LDC cr,r” instruction.
Channel 0
DMAS0
DMA Source address register 0 : only use LSB 24bits
DMAD0
DMA Destination address register 0 : only use LSB 24bits
DMAC0
DMA Counter register 0 : 1 to 65536
DMAM0
DMA Mode register 0
Channel 3
DMAS3
DMA Source address register 3
DMAD3
DMA Destination address register 3
DMAC3
DMA Counter register 3
DMAM3
DMA Mode register 3
8 bits
16 bits
32 bits