Chain Transfer - Hitachi H8S/2378, H8S/2378R Series Hardware Manual

SAR
or
DAR
Figure 9.7 Memory Mapping in Block Transfer Mode
9.5.4

Chain Transfer

Setting the CHNE bit to 1 enables a number of data transfers to be performed consecutively in
response to a single transfer request. SAR, DAR, CRA, CRB, MRA, and MRB, which define data
transfers, can be set independently.
Figure 9.8 shows the operation of chain transfer. When activated, the DTC reads the register
information start address stored at the vector address, and then reads the first register information
at that start address. The CHNE bit in MRB is checked after the end of data transfer, if the value is
1, the next register information, which is located consecutively, is read and transfer is performed.
This operation is repeated until the end of data transfer of register information with CHNE = 0. It
is also possible, by setting both the CHNE bit and CHNS bit to 1, to specify execution of chain
transfer only when the transfer counter value is 0.
In the case of transfer with CHNE set to 1, an interrupt request to the CPU is not generated at the
end of the specified number of transfers or by setting of the DISEL bit to 1, and the interrupt
source flag for the activation source is not affected.
First block
Transfer
Nth block
Block area
Rev. 1.0, 09/01, page 393 of 904
DAR
or
SAR