Rev. 3.0, 10/02, page 172 of 686
7.4.5
Normal Mode
In normal mode, transfer is performed with channels A and B used in combination. Normal mode
can be specified by setting the FAE bit in DMABCR to 1 and clearing the BLKE bit in DMACRA
to 0. In normal mode, MAR is updated after each byte or word transfer in response to a single
transfer request, and this is executed the number of times specified in ETCRA. The transfer source
is specified by MARA, and the transfer destination by MARB. Table 7.6 summarizes register
functions in normal mode.
Table 7.6
Register Functions in Normal Mode
Register
Function
Initial Setting
Operation
23
0
MARA
Source address
register
Start address of
transfer source
Incremented/decremented
every transfer, or fixed
23
0
MARB
Destination address
register
Start address of
transfer destination
Incremented/decremented
every transfer, or fixed
0
15
ETCRB
Transfer counter
Number of transfers Decremented every
transfer; transfer ends
when count reaches
H'0000
MARA and MARB specify the start addresses of the transfer source and transfer destination,
respectively, as 24 bits. MAR can be incremented or decremented by 1 or 2 each time a byte or
word is transferred, or can be fixed. Incrementing, decrementing, or holding a fixed value can be
set separately for MARA and MARB.
The number of transfers is specified by ETCRA as 16 bits. ETCRA is decremented each time a
transfer is performed, and when its value reaches H'0000 the DTE bit is cleared and transfer ends.
If the DTIE bit is set to 1 at this time, an interrupt request is sent to the CPU or DTC. The
maximum number of transfers, when H'0000 is set in ETCRA, is 65,536.
Summary of Contents for H8S/2215 Series
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