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C161U
Asynchronous/Synchr. Serial Interface
Data Sheet
253
2001-04-19
12
Asynchronous/Synchr. Serial Interface
Asynchronous/Synchronous Serial Interface (ASC) provides serial communication
between the C161U and other microcontrollers, microprocessors or external peripherals.
The ASC supports a certain protocol to transfer data via a serial interconnection.
12.1
Functional Description
ASC supports full-duplex asynchronous communication up to 2.25 MBaud and half-
duplex synchronous communication up to 4.5 MBaud (@ 36 MHz CPU clock which is
equal to the ASC module clock). In synchronous mode, data are transmitted or received
synchronous to a shift clock which is generated by the microcontroller. In asynchronous
mode, 8- or 9-bit data transfer, parity generation, and the number of stop bits can be
selected.
12.1.1
Features
Full duplex asynchronous operating modes
– 8- or 9-bit data frames, LSB first
– Parity bit generation/checking
– One or two stop bits
– Baudrate from 2.25 MBaud to 0.5364 Baud (@ 36 MHz module clock = CPU clock)
– Multiprocessor mode for automatic address/data byte detection
– Loop-back capability
– Support for IrDA data transmission/reception up to max. 115.2 kBaud
Autobaud detection unit for asynchronous operating modes
– Detection of standard baudrates
1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200, 230400 Baud
– Detection of non-standard baudrates
– Detection of asynchronous modes
7-bit, even parity; 7-bit, odd parity;
8-bit, even parity; 8-bit, odd parity; 8-bit, no parity
– Automatic initialization of control bits and baudrate generator after detection
– Detection of a serial two-byte ASCII character frame
Recently introduced fractional divider
– The fractional divider drastically improves the accuracy of the adjustment for
baudrates
– Standard Baud Rates generation with very small deviation (230.4 kBaud < 0.01%,
460.8 kBaud < 0.15 %, 691.2 kBaud < 0.04 %, 921.6 kBaud < 0.15 % ) @ 36 MHz