Activation Sources; Figure 7.2 Block Diagram Of Dtc Activation Source Control - Renesas H8S/2158 User Manual

Section 7 Data Transfer Controller (DTC)
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
diagram of DTC activation source control. For details on the interrupt controller, see section 5,
Interrupt Controller.
Source flag cleared
Clear
controller
Clear
DTCER
Clear request
Select
On-chip
DTC
peripheral
module
IRQ interrupt
Interrupt
request
CPU
Interrupt controller
DTVECR
Interrupt mask

Figure 7.2 Block Diagram of DTC Activation Source Control

Rev. 3.00 Jan 25, 2006 page 152 of 872
REJ09B0286-0300