UART Serial Ports
Élan™SC520 Microcontroller User’s Manual
21-9
If receiver line status interrupts are enabled, any of the OE, PE, FE, or BI conditions trigger
an interrupt. Note that the ERR_IN_FIFO cannot directly generate an interrupt.
21.5.4
Configuration Information
21.5.4.1
Baud Rate
To generate the baud rate of the transfer, the UART clock is divided by a divisor value
chosen by the programmer. The UART’s baud-rate generator automatically calculates the
baud rate from the divisor value programmed into the two UART x Baud Clock Divisor Latch
MSB and LSB registers. These registers are read at initialization to set the baud rate for
the transfer. The baud rate is calculated according to the following equation:
Baudrate = clockfrequency / 16 * BAUDDIV
Here, clock frequency refers to the frequency of the main reference clock, 1.8432 MHz or
18.432 MHz. This frequency is determined by the CLKSRC bit in the UART x General
Control (UARTxCTL) register. BAUDDIV is defined by the UART x Baud Clock Divisor Latch
MSB and LSB registers. Table 21-5 lists the divisor value (in decimal and hexadecimal) to
use with each clock frequency to achieve common baud rates.
21.5.4.2
Hardware Flow Control
When the EMSI bit of the UART x Interrupt Enable (UARTxINTENB) register is set, the
modem status interrupt is enabled to facilitate the hardware flow control. The interrupts are
triggered by changes in the following control lines: CTSx, DTRx, RINx, and DCDx.
21.5.4.3
Operating Modes
16450-compatible UART mode and 16550-compatible UART mode can be setup by setting
or clearing the FIFO_ENB bit of UART x FIFO Control (UARTxFCR) register. The
ÉlanSC520 microcontroller UARTs can be switched between the 16550-compatible mode
and 16450-compatible mode under software control.
Table 21-5
Baud Rates, Divisors, and Clock Source
Baud Rate
DIV[15–0] (Decimal)
DIV[15–0] (Hexadecimal)
1.8432 MHz
18.432 MHz
1.8432 MHz
18.432 MHz
300 baud
384d
3840d
0180h
0F00h
600 baud
192d
1920d
00C0h
0780h
2400 baud
48d
480d
0030h
01E0h
4800 baud
24d
240d
0018h
00F0h
7200 baud
16d
160d
000Fh
00A0h
9600 baud
12d
120d
000Ch
0078h
14.4 kbaud
8d
80d
0008h
0050h
19.2 kbaud
6d
60d
0006h
003Ch
57.6 kbaud
2d
20d
0002h
0014h
115.2 kbaud
1d
10d
0001h
000Ah
144 kbaud
8d
0008h
192 kbaud
6d
0006h
288 kbaud
4d
0004h
576 kbaud
2d
0002h
1.152 Mbaud
1d
0001h
Содержание Elan SC520
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Страница 78: ...System Initialization 3 22 lan SC520 Microcontroller User s Manual...
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Страница 118: ...Reset Generation 6 10 lan SC520 Microcontroller User s Manual...
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Страница 288: ...GP Bus DMA Controller 14 22 lan SC520 Microcontroller User s Manual...
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Страница 328: ...Software Timer 18 4 lan SC520 Microcontroller User s Manual...
Страница 346: ...Real Time Clock 20 12 lan SC520 Microcontroller User s Manual...
Страница 360: ...UART Serial Ports 21 14 lan SC520 Microcontroller User s Manual...
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