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13. DMACII
13.3.2
Immediate Data Transfer
DMACII transfers immediate data to a given memory location. A fixed or incremented address can be selected
as a destination address. Store immediate data into SADR. To transfer an 8-bit immediate data, write data in
one low-order byte of SADR (high-order byte is ignored).
13.3.3
Calculation Transfer
After two memory data, or an immediate data and a memory data, are added together, DMACII transfers the
calculated result to a given memory location. SADR must have one memory location address to be calculated or
immediate data. OADR must have another memory location address to be calculated. To use a “memory +
memory” calculation transfer, a fixed or incremented address can be selected as source and destination
addresses. If a source address is incremented, an operation address also becomes incremented. To use an
“immediate data + memory” calculation transfer, a fixed or incremented address can be selected as a destination
address.
13.4
Transfer Modes
In DMACII, single transfer, burst transfer, and multiple transfer are available. The BRST bit in MOD selects either
single transfer or burst transfer, and the MULT bit in MOD selects the multiple transfer. COUNT determines how
many transfers occur. No transfer occurs when COUNT is set to 0000h.
During these transfers, no interrupt can be acknowledged.
13.4.1
Single Transfer
For one transfer request, DMACII transfers an 8-bit or 16-bit data once. When an incremented address is
selected for a source or destination address, DMACII increments the address after every transfer for the
following transfer.
DMACII decrements COUNT every time a transfer occurs. If using the end-of-transfer interrupt, the interrupt
occurs when COUNT reaches zero.
13.4.2
Burst Transfer
For one transfer request, DMACII continuously transfers data the number of times determined by COUNT.
The burst transfer ends when COUNT reaches zero. If using the end-of-transfer interrupt, the interrupt occurs
when the burst transfer is completed. While the burst transfer is taking place, no interrupt can be acknowledged.
13.5
Multiple Transfer
The multiple transfer can be selected with the MULT bit in MOD. When using the multiple transfer, select the
memory-to-memory transfer. For one transfer request, DMACII transfers data multiple times. Bits CNT2 to CNT0
in MOD selects the number of transfers from 001b (once) to 111b (7 times). Do not set bits CNT2 to CNT0 to
000b.
Source and destination addresses enough for every transfer must be allocated alternately in addresses following
MOD and COUNT in DMACII index.
While the transfers are performed the number of times set with bits CNT2 to CNT0, no interrupt can be
acknowledged. When the multiple transfer is selected, the calculation transfer, burst transfer, chain transfer, and
end-of-transfer interrupt cannot be used.