Under
development
Preliminary Specifications REV.B3
Specifications in this manual are tentative and subject to change.
Mitsubishi Microcomputers
M32C/83 group
SINGLE-CHIP 16/32-BIT CMOS MICROCOMPUTER
DMAC
118
Memory expansion mode
Microprocessor mode
Single-chip mode
(2) DMAC transfer cycles
Any combination of even or odd transfer read and write addresses is possible. Table 1.11.2 shows the
number of DMAC transfer cycles.
The number of DMAC transfer cycles can be calculated as follows:
No. of transfer cycles per transfer unit = No. of read cycles x j + No. of write cycles x k
Table 1.11.2. No. of DMAC transfer cycles
Transfer unit
Bus width
Access address
No. of read
No. of write
No. of read No. of write
cycles
16-bit
Even
1
8-bit transfers
(DSi = “1”)
Odd
1
(BWi = “0”)
8-bit
Even
——
11
(DSi = “0”)
Odd
——
11
16-bit
Even
1
16-bit transfers
(DSi = “1”)
Odd
2
(BWi = “1”)
8-bit
Even
——
22
(DSi = “0”)
Odd
——
22
Coefficient j, k
Internal memory
External memory
Coefficient j
Coefficient k
Internal ROM/RAM
No wait
1
Internal ROM/RAM
One wait
2
SFR area
2
Separate bus
No wait
1
2
Separate bus
One wait
2
Separate bus
Two waits
3
Separate bus
Three waits
4
Multiplex bus
3
DMA Request Bit
The DMAC can issue DMA requests using preselected DMA request factors for each channel as triggers.
The DMA transfer request factors include the reception of DMA request signals from the internal periph-
eral functions, software DMA factors generated by the program, and external factors using input from
external interrupt signals.
See the description of the DMAi factor selection register for details of how to select DMA request factors.
DMA requests are received as DMA requests when the DMAi request bit is set to “1” and the channel i
transfer mode select bits are “01” or “11”. Therefore, even if the DMAi request bit is “1”, no DMA request
is received if the channel i transfer mode select bit is “00”. In this case, DMAi request bit is cleared.
Because the channel i transfer mode select bits default to “00” after a reset, remember to set the channel
i transfer mode select bit for the channel to be activated after setting the DMAC related registers. This
enables receipt of the DMA requests for that channel, and DMA transfers are then performed when the
DMAi request bit is set.
The following describes when the DMAi request bit is set and cleared.