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ManualsBrandsRENESAS ManualsMicrocontrollers, Microprocessors & QuartzesEmbedded microcontroller LQFP 80 (14x14) 16-Bit 20 MHz I/O number 69
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Section 12 Event Link Controller
Page 396 of 982 REJ09B0465-0300 Rev. 3.00
Sep 17, 2010
H8S/20103, H8S/20203, H8S/20223, H8S/20115, H8S/20215, H8S/20235 Group
(6) Operation of Port Buffer Registers
(a) Input Port-Groups
When an event is input to an input port-group, the signal value of the external pin of the bit
specified as the members of the input port-group is transferred to PDBF. If another event is input
to the input port-group in this state, the current PDR value is transferred or not depending on the
PGCOVE bit setting in PGC as described below.
• PGCOVE = 0 (overwriting PDBF is disabled)
If the PDBF value that has been transferred upon the latest event input has already been read
by the CPU (or transferred by the DTC), the signal value of the external pin is transferred to
PDBF. If not read, the signal value of the external pin is not transferred and the input event is
invalid.
• PGCOVE = 1 (overwriting PDBF is enabled)
When another event is input to an input port-group, the signal value of the external pin is
transferred to PDBF.
(b) Output Port-Groups
If an output port-group is specified so that it should output the PDBF value, the PDBF value is
transferred to PDR when an event is input to the output port-group. In this case, only the values of
the bits specified as the members of the output port-group are transferred
If an output port-group is specified so that it should shift out the bit values in the group (PGCO
bits = 1xx in PGC), the PDBF data is transferred to PDR, and then the PDR value is shifted bit by
bit from MSB to LSB. The initial value to be output to the port-group should be provided in
PDBF.
Examples of operation are shown in figures 12.5 and 12.6.
(7) Restrictions on Writing to PDR or PDBF by CPU
When the ELCON bit in ELCR is set to 1, write access to the following registers is invalid.
• If bits are specified as members of the input port-group and the event-linkage is set for the
port-group, write access to the relevant bits in PDBF by the CPU is invalid.
• If port bits are specified as members of the output port-group, write access to the relevant bits
in PDR by the CPU is invalid.
• If a port bit is specified as an output single-port and the event-linkage is set (by ELSR) for the
port, write access to the relevant bit in PDR by the CPU is invalid.