R01UH0823EJ0100 Rev.1.00
Page 381 of 1823
Jul 31, 2019
RX23W Group
19. Data Transfer Controller (DTCa)
19.2
Register Descriptions
Registers MRA, MRB, SAR, DAR, CRA, and CRB are DTC internal registers, which cannot be directly accessed from
the CPU. Values to be set in these DTC internal registers are placed in the RAM area as transfer information. When
accepting a transfer request, the DTC reads the transfer information from the RAM area and sets it in the internal
registers. After the data transfer ends, the values of the updated internal register are written back to the RAM area as
transfer information.
19.2.1
DTC Mode Register A (MRA)
MRA register is used to select the DTC operating mode and cannot be accessed directly from the CPU.
Address(es): (inaccessible directly from the CPU)
b7
b6
b5
b4
b3
b2
b1
b0
MD[1:0]
SZ[1:0]
SM[1:0]
—
—
Value after reset:
x
x
x
x
x
x
x
x
x: Undefined
Bit
Symbol
Bit Name
Description
R/W
b1, b0
—
Reserved
Set these bits to 0.
—
b3, b2
Transfer Source Address Addressing
Mode
b3 b2
0 0: The address in the SAR register is fixed.
(write-back to SAR is skipped.)
0 1: The address in the SAR register is fixed.
(write-back to SAR is skipped.)
1 0: The SAR value is incremented after a data transfer.
(+1 when the SZ[1:0] bits are 00b, +2 when 01b, +4
when 10b)
1 1: The SAR value is decremented after a data transfer.
(–1 when the SZ[1:0] bits are 00b, –2 when 01b, –4
when 10b)
—
b5, b4
DTC Data Transfer Size
b5 b4
0 0: Byte (8-bit) transfer
0 1: Word (16-bit) transfer
1 0: Longword (32-bit) transfer
1 1: Setting prohibited
—
b7, b6
DTC Transfer Mode Select
b7 b6
0 0: Normal transfer mode
0 1: Repeat transfer mode
1 0: Block transfer mode
1 1: Setting prohibited
—