
C165H
Asynchronous/Synchr. Serial Interface
Data Sheet
262
2001-04-19
PRELMNARY
-EXCERPT-
TXD and RXD will go high, the transmit interrupt request line TIR is activated, and serial
data transmission stops.
Pin P3.10/TXD must be configured for alternate data output in order to provide the shift
clock. Pin P3.11/RXD must also be configured for output during transmission.
Synchronous reception is initiated by setting bit CON_REN=’1’. If bit CON_R=1, the data
applied at RXD is clocked into the receive shift register synchronous to the clock which
is output at pin TXD. After the 8th bit has been shifted in, the content of the receive shift
register is transferred to the receive data buffer RBUF, the receive interrupt request line
RIR is activated, the receiver enable bit CON_REN is reset, and serial data reception
stops.
Pin P3.10/TXD must be configured for alternate data output in order to provide the shift
clock. Pin P3.11/RXD must be configured as alternate data input.
Synchronous reception is stopped by clearing bit CON_REN. A currently received byte
is completed including the generation of the receive interrupt request and an error
interrupt request, if appropriate. Writing to the transmit buffer register while a reception
is in progress has no effect on reception and will not start a transmission.
If a previously received byte has not been read out of the receive buffer register at the
time the reception of the next byte is complete, both the error interrupt request line EIR
and the overrun error status flag CON_OE will be activated/set, provided the overrun
check has been enabled by bit CON_OEN.
11.1.6.3
Synchronous Timing
Figure 85
shows timing diagrams of the ASC synchronous mode data reception and
data transmission. In idle state the shift clock is at high level. With the beginning of a
synchronous transmission of a data byte the data is shifted out at RXD with the falling
edge of the shift clock. If a data byte is received through RXD data is latched with the
rising edge of the shift clock.
Between two consecutive receive or transmit data bytes one shift clock cycle (f
BR
) delay