ML51/ML54/ML56
Sep. 01, 2020
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Manual
6.9 Serial Port (UART0 & UART1)
6.9.1
Overview
The ML51/ML54/ML56 Series includes two enhanced full duplex serial ports enhanced with automatic
address recognition and framing error detection. As control bits of these two serial ports are
implemented the same. Generally speaking, in the following contents, there will not be any reference
to serial port 1, but only to serial port 0.
Each serial port supports one synchronous communication mode, Mode 0, and three modes of full
duplex UART (Universal Asynchronous Receiver and Transmitter), Mode 1, 2, and 3. This means it
can transmit and receive simultaneously. The serial port is also receiving-buffered, meaning it can
commence reception of a second byte before a previously received byte has been read from the
register. The receiving and transmitting registers are both accessed at SBUF. Writing to SBUF loads
the transmitting register, and reading SBUF accesses a physically separate receiving register. There
are four operation modes in serial port. In all four modes, transmission initiates by any instruction that
uses SBUF as a destination register.
6.9.2
Features
Supports up to 2 UARTs: UART0, UART1
Supports 2 Smart Card configuration as UART function as UART2 and UART3.
UART baud rate clock from HIRC or HXT.
Full-duplex asynchronous communications
Programmable 9th bit.
TXD and RXD pins of UART0 exchangeable via software.
