Operation; Clock; Data Transfer Format - Renesas Hitachi H8S/2194 Series Hardware Manual

24.3

Operation

The SCI2, comprising 32 bytes serial data buffer, can continuously transmit a maximum of 32
bytes data by a single operation, synchronized with clock pulse. Installation of a register enables
to select transmit, receive, or simultaneous transmit/receive. When transmit is set, the value of
serial data buffer is retained even after completion of transmission.
An internal or external clock can be selected as transfer clock. When an internal clock is
selected, data can be transmitted at 1-byte intervals. The strobe signal can also be output from
the STRB pin. When an external clock is selected, malfunction due to clock can be detected by
the overrun flag.
The start of transfer and its forced cutoff can be controlled by
detected by the abort flag.
24.3.1

Clock

Selection of a transfer clock can be made from seven internal clocks and an external clock.
When an internal clock is selected, the SCK2 pin becomes a clock output pin.
24.3.2

Data Transfer Format

Figures 24.2 and 24.3 show transfer format of the SCI2.
LSB-first transfer that allows to transmit/receive from the lowest-order bit of data is performed.
Transmit data is output from the fall of the transfer clock to its next fall. Receive data is
collected at the rise of the transfer clock.
When an internal clock is selected as a transfer clock, data can be transferred at intervals of 1
byte. The SCK2 output is retained at a high level between transfer data. The strobe signal can
be output from the STRB pin.
Selection of interval of transfer data is set at GAP1 or GAP0.
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input. Forced cutoff can be