DMAC II
deveopmen
Rev.B2 for proof reading
Mitsubishi Microcomputers
M32C/83 group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
127
(2) Burst transfer
For a DMAC II transfer request, data transfers are performed in succession a number of times as set
by the DMAC II Index transfer counter. When using the end-of-transfer interrupt facility, an end-of-
transfer interrupt is generated at the time a burst transfer finishes (i.e., when the transfer counter
reaches zero after being decremented for each data transfer performed).
(3) Multiple transfers
For multiple transfers, use the multiple transfer select bit (bit 15) for transfer mode setup in the DMAC
II Index. Setting this bit to 1 selects the multiple transfer function. For the multiple transfer function,
memory to memory transfer can be performed.
Multiple transfers are performed for one DMAC II transfer request received. Use DMAC II Index trans-
fer mode bits 4
–
6 to set the number of transfers to be performed. (Setting these bits to 001 performs
one transfer; setting these bits to 111 performs 7 transfers. Setting these bits to 000 is inhibited.)
The transfer source and transfer destination addresses are alternately incremented beginning with the
DMAC II Index BASE address + 4 (as many times as the number of transfers performed).
When using multiple transfer function, arithmetic transfer, burst transfer, end-of-transfer interrupt and
chained transfer cannot be used.
(4) Chained transfer
For chained transfers, use the chained transfer select bit (bit 7) for transfer mode setup in the DMAC
II Index. Setting this bit to 1 selects the chained transfer function. The following describes how a
chained transfer is performed.
1) When a DMA II transfer request (interrupt request from any peripheral I/O) is received, a DMAC II
Index transfer is performed corresponding to the received request.
2) When the DMAC II Index transfer counter reaches zero, the chained transfer address in the DMAC
II Index (i.e., the start address of the DMAC II Index that contains a description of the next DMAC II
transfer to be performed) is written to the relocatable vector table for the peripheral I/O.
3) From the next DMA II transfer request on, transfers are performed based on the DMAC II Index
indicated by the rewritten relocatable vector table of the peripheral I/O.
Before the chained transfer function can be used, the relocatable vector table must be located in the
RAM area.
(5) End-of-transfer interrupt
For end-of-transfer interrupts, use the end-of-transfer interrupt select bit (bit 6) for transfer mode setup
in the DMAC II Index. Setting this bit to 1 selects the end-of-transfer interrupt function. Set the jump
address for end-of-transfer interrupt processing in the DMAC II Index
’
s end-of-transfer interrupt ad-
dress field. An end-of-transfer interrupt is generated when the DMAC II Index transfer counter reaches
zero.