RX610 Group
13. Data Transfer Controller (DTC)
R01UH0032EJ0120 Rev.1.20
Page 352 of 1006
Feb 20, 2013
13.4.1
Transfer Data Read Skip Function
Vector address read and transfer data read can be skipped by the setting of the RRS bit in DTCCR.
When a DTC startup request is generated, the current DTC vector number is always compared with the DTC vector
number in the previous startup process. When these vector numbers match and the RRS bit is set to 1, DTC data transfer
is performed without reading the vector address and transfer data. However, when the previous transfer was chain
transfer, the vector address and transfer data are always read. Furthermore, when the transfer counter (CRA register)
became 0 during the previous normal transfer and when the transfer counter (CRB register) became 0 during the previous
block transfer, transfer data is always read regardless of the value of RRS bit. Figure 13.5 shows an example of transfer
data read skip.
To update the vector table and transfer data, set the RRS bit to 0, update the vector table and transfer data, and then set
the RRS bit to 1. When the RRS bit is set to 0, the retained vector number is discarded and the vector table and transfer
data that are updated in the following startup process are read.
System clock
ICU.IRi
Request for DTC
activation
Access by DTC
Reading
the
vector
Reading the
transfer-
control
information
Read-skipping
enable
(2)
Note: Since the activation request (vector number) is the same at points (1) and (2), if bit RRS = 1, reading of the transfer-control information is
skipped for request (2).
W
R
W
(1)
i = DTC vector number (interrupt vector number)
R
Writing the
transfer-
control
information
Transferr
ing data
Writing the
transfer-
control
information
Transferri
ng data
Figure 13.5 Operation with Skipping of the Transfer-Control Information