NuMicro™ Mini51 Technical Reference ManualFeb 9, 2012 Page 267 of 342 Revision V1.03NUMICRO™ MINI51 TECHNICAL REFERENCE MANUAL5.13 UART Interface ControllerThe NuMicro Mini51 series provides one channel of Universal AsynchronousReceiver/Transmitters (UART). UART performs Normal Speed UART, and support flow controlfunction.5.13.1 OverviewThe Universal Asynchronous Receiver/Transmitter (UART) performs a serial-to-parallel conversionon data received from the peripheral, and a parallel-to-serial conversion on data transmitted fromthe CPU. The UART controller also supports IrDA SIR function, and RS-485 mode functions. EachUART channel supports six types of interrupts, including transmitter FIFO empty interrupt(INT_THRE), receiver threshold level reaching interrupt (INT_RDA), line status interrupt (parityerror or framing error or break interrupt) (INT_RLS), receiver buffer time-out interrupt (INT_TOUT),MODEM/Wake-up status interrupt (INT_MODEM), and Buffer error interrupt (INT_BUF_ERR).Interrupt number 12 (vector number is 28) supports UART interrupt. Refer to Nested VectoredInterrupt Controller chapter for System Interrupt Map.The UART is built-in with a 16-byte transmitter FIFO (TX_FIFO) and a 16-byte receiver FIFO(RX_FIFO) that reduces the number of interrupts presented to the CPU and the CPU can read thestatus of the UART at any time during the operation. The reported status information includes thetype and condition of the transfer operations being performed by the UART, as well as 4 errorconditions (parity error, framing error, break interrupt and buffer error) probably occur whilereceiving data. The UART includes a programmable baud rate generator that is capable of dividingcrystal clock input by divisors to produce the clock that transmitter and receiver need. The baudrate equation is Baud Rate = UART_CLK / M * [BRD + 2], where M and BRD are defined in BaudRate Divider Register (UA_BAUD). The following table lists the equations in the various conditionsand the UART baud rate setting table.Table 5.13-1 UART Baud Rate Setting TableMode DIV_X_EN DIV_X_ONE Divider X BRD Baud Rate Equation0 0 0 B A UART_CLK / [16 * (A+2)]1 1 0 B A UART_CLK / [(B+1) * (A+2)] , B must>= 82 1 1 Don‟t care A UART_CLK / (A+2), A must >=3Table 5.13-2 UART Baud Rate Setting TableSystem clock = 22.1184 MHzBaud rate Mode0 Mode1 Mode2921600 Not Support A=0, B=11 A=22460800 A=1 A=1, B=15A=2, B=11 A=46230400 A=4 A=4, B=15A=6, B=11 A=94115200 A=10 A=10, B=15 A=190
