TC1796
Peripheral Units (Vol. 2 of 2)
Asynchronous/Synchronous Serial Interface (ASC)
User’s Manual
19-9
V2.0, 2007-07
ASC, V2.0
19.1.4
Synchronous Operation
Synchronous Mode supports half-duplex communication, usable for simple I/O
expansion via shift registers. Data is transmitted and received via pin RXD while pin TXD
outputs the shift clock. These signals are typically connected as alternate functions with
GPIO port pins. Synchronous Mode is selected with CON.M = 000
B
.
Eight data bits are transmitted or received synchronous to a shift clock generated by the
internal baud rate generator. The shift clock is active only as long as data bits are
transmitted or received.
Figure 19-6 Synchronous Mode of Serial Channel ASC
MUX
Serial Port Control
MCA05767
BRS
f
BRT
f
DIV
R
f
ASC
f
BR
REN
OEN
LB
Receive Int. Req.
Transmit Int. Req.
Transmit Buffer Int. Req.
Error Int. Req.
EIR
TBIR
TIR
RIR
M = 000
B
OE
Shift Clock
Shift Clock
Receive Shift
Register
Transmit Shift
Register
Receive
Buffer Reg.
RBUF
Transmit
Buffer Reg.
TBUF
RXD
Internal Bus
TXD
0
1
MUX
4
2
3
13-Bit Baud Rate Timer
13-Bit Reload Register