HD64F2145 Datasheet, PDF (180/829 Pages) Renesas Technology Corp – Hitachi 16-Bit Single-Chip Microcomputer

7.2.8 DTC Vector Register (DTVECR)
DTVECR enables or disables DTC activation by software, and sets a vector number for the
software activation interrupt.
Bit Bit Name
7 SWDTE
6 DTVEC6
5 DTVEC5
4 DTVEC4
3 DTVEC3
2 DTVEC2
1 DTVEC1
0 DTVEC0
Initial Value R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
Description
DTC Software Activation Enable
Setting this bit to 1 activates DTC. Only 1 can always be
written to this bit. 0 can be written to after reading 1
from this bit.
[Clearing conditions]
• When the DISEL bit is 0 and the specified number of
transfers have not ended.
• When 0 is written to the DISEL bit after a software-
activated data transfer end interrupt (SWDTEND)
request has been sent to the CPU.
[Holding conditions]
• When the DISEL bit is 1 and data transfer has
ended
• When the specified number of transfers have ended.
• During data transfer activated by software
DTC Software Activation Vectors 6 to 0
These bits specify a vector number for DTC software
activation.
The vector address is expressed as H'0400 + (vector
number × 2). For example, when DTVEC6 to DTVEC0 =
H'10, the vector address is H'0420. When the SWDTE
bit is 0, these bits can be written to.
7.3 Activation Sources
The DTC is activated by an interrupt request or by a write to DTVECR by software. The interrupt
request source to activate the DTC is selected by DTCER. At the end of a data transfer (or the last
consecutive transfer in the case of chain transfer), the interrupt flag that became the activation
source or the corresponding DTCER bit is cleared. The activation source flag, in the case of RXI0,
for example, is the RDRF flag in SCI_0.
When an interrupt has been designated as a DTC activation source, the existing CPU mask level
and interrupt controller priorities have no effect. If there is more than one activation source at the
same time, the DTC operates in accordance with the default priorities. Figure 7.2 shows a block
Rev. 2.0, 08/02, page 140 of 788