HD6417034B RENESAS [Renesas Technology Corp], HD6417034B Datasheet - Page 228

• Manufacturer Part Number: HD6417034B
• Description: 32-Bit RISC Microcomputer
• Manufacturer: RENESAS [Renesas Technology Corp]

Section 9 Direct Memory Access Controller (DMAC)
Rev. 7.00 Jan 31, 2006 page 202 of 658
REJ09B0272-0700
Two types of transfers are possible in single address mode: 1) transfers between external
devices with DACK and memory-mapped external devices, and 2) transfers between external
devices with DACK and external memory. The only transfer request for either of these is the
external request (DREQ). Figure 9.7 shows the DMA transfer timing for single address mode.
The DACK output when a transfer occurs from an external device with DACK to a memory-
mapped external device is the write waveform. The DACK output when a transfer occurs from
a memory-mapped external device to an external device with DACK is the read waveform.
The settings of the acknowledge mode (AM) bits in the channel control registers (CHCR0,
CHCR1) have no effect.
Note: The read/write direction is decided by the RS3-RS0 bits in the CHCRn registers. If
RS3-RS0 = 0010, the direction is as shown in case 1 (circled number above); if RS3-
RS0 = 0011, the direction is as shown in case 2. In the Electrical Characteristics
section, DACK output (read) indicates case 1, and DACK output (write) indicates
case 2.
SuperH microcomputer
External address bus
DMAC
Figure 9.6 Data Flow in Single Address Mode
: Data flow
DREQ
DACK
External data bus
Read Write
1
2
External device
with DACK
External
memory