9
DMAC
9-15
32176 Group User’s Manual (Rev.1.01)
9.2.5 DMA Transfer Count Registers
DMA0 Transfer Count Register (DM0TCT)
<Address: H’0080 0411>
DMA1 Transfer Count Register (DM1TCT)
<Address: H’0080 0421>
DMA2 Transfer Count Register (DM2TCT)
<Address: H’0080 0431>
DMA3 Transfer Count Register (DM3TCT)
<Address: H’0080 0441>
DMA4 Transfer Count Register (DM4TCT)
<Address: H’0080 0451>
DMA5 Transfer Count Register (DM5TCT)
<Address: H’0080 0419>
DMA6 Transfer Count Register (DM6TCT)
<Address: H’0080 0429>
DMA7 Transfer Count Register (DM7TCT)
<Address: H’0080 0439>
DMA8 Transfer Count Register (DM8TCT)
<Address: H’0080 0449>
DMA9 Transfer Count Register (DM9TCT)
<Address: H’0080 0459>
<Upon exiting reset: Undefined>
b
Bit Name
Function
R
W
8–15
DM0TCT–DM9TCT
DMA transfer count
R
W
DMA transfer count
(Has no effect during ring buffer mode)
The DMA Transfer Count Register is used to set the number of times data is transferred on each channel.
However, the value in this register has no effect during ring buffer mode.
The transfer count is the (value set in the transfer count register + 1). Because the DMA Transfer Count Register
is comprised of a current register, the values read from this register are always the current value. (However, if
the register is read in a cycle immediately after transfer, the value obtained is one that was stored in the count
register before the transfer began.) When transfer finishes, this count register underflows and the value read
from it is H’FF.
When transfer is enabled, this register is protected in hardware and cannot be accessed for write.
During ring buffer mode, the register counts down in free-run mode and continues counting until transfer is
disabled. No interrupt is generated at underflow.
If any cascaded channel exists, each time one DMA transfer (byte or halfword) is completed or when all trans-
fers on a channel are completed (i.e., the transfer count register underflows), transfer on the cascaded channel
starts.
9.2 DMAC Related Registers
b8
9
10
11121314
b15
DM0TCT-DM9TCT
???
????
?
