11.4.3 Baud-rate Generator
The baud-rate generator outputs internal clocks: Baud16 and IrLPBaud16. Baud16 generates the timing for
UART transmission/reception control. IrLPBaud16 generates a pulse width of IrDA encode transmit bit
stream in the low power mode.
The baud-rate is calculated by the following equation using the f
UARTCLK
input from the UART and a baud-
rate divisor.
Baud-rate = (f
UARTCLK
) / (16 x baud-rate divisor)
11.4.3.1 Calculating A Baud-rate Divisor
The baud-rate divisor is calculated as follows:
Baud-rate divisor BAUDDIV = (f
UARTCLK
) / (16 x baud rate)
where f
UARTCLK
is a clock frequency of UART.
BAUDDIV consists of the integer part (BAUDDIVINT) and fractional part (BAUDDIVFRAC).
Example: Calculation of the divisor
If the required baud-rate is 230400 and f
UARTCLK
= 4 MHz
Baud rate divisor = (4 × 10
6
)/ (16 × 230400) = 1.085
Accordingly, the integer part of baud-rate (BAUDDIVINT) = 1 and the fractional part of baud-rate =
0.085
Therefore, BAUDDIVFRAC is calculated as follows:
BAUDDIVFRAC = ((0.085 × 64) + 0.5) = 5.94 = 5 (Figures below the decimal point are omitted.)
Generated baud-rate divisor is calculated using the above integer part and fractional part as below:
BAUDDIV = 1 + 5/64 = 1.078
At this time, generated baud-rate is calculated as follows:
Generated baud-rate = (4 × 10
6
)/ (16 × 1.078) = 231911
A margin of error = (231911 - 230400)/ 230400 × 100 = 0.656%
In addition, the maximum margin of error is 1/64 × 100 = 1.56% when the UARTxFBRD register is
used. This margin of error is generated when UARTxFBRD = 1.
11.4.4 Transmit Logic
The transmit logic performs parallel-to-serial conversion on data read out from the transmit FIFO. Control
logic outputs the signal beginning with a start bit, data bits starting with LSB, parity bit, and the stop bit, accord-
ing to the specified configuration in the control registers.
11.4.5 Receive Logic
The receive logic performs serial-to-parallel conversion on the received bit stream after the start bit has
been detected. Error checking for overrun, parity, frame and line break detection are also performed. Data rela-
ted to an error bit for overrun, parity, framing and break is written to the receive FIFO.
TMPM3V6/M3V4
11. Universal Asynchronous Receiver-Transmitter Circuit (UART)
11.4 Operation Description
Page 204
2019-02-06
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Страница 2: ... 2019 Toshiba Electronic Devices Storage Corporation ...
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Страница 178: ...TMPM3V6 M3V4 9 Input Output port 9 2 Block Diagrams of Ports Page 156 2019 02 06 ...
Страница 206: ...TMPM3V6 M3V4 10 16 bit Timer Event Counters TMRB 10 7 Applications using the Capture Function Page 184 2019 02 06 ...
Страница 232: ...TMPM3V6 M3V4 11 Universal Asynchronous Receiver Transmitter Circuit UART 11 4 Operation Description Page 210 2019 02 06 ...
Страница 354: ...TMPM3V6 M3V4 14 Synchronous Serial Port SSP 14 6 Frame Format Page 332 2019 02 06 ...
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Страница 462: ...TMPM3V6 M3V4 21 Watchdog Timer WDT 21 5 Control register Page 440 2019 02 06 ...
Страница 510: ...TMPM3V6 M3V4 22 Flash Memory Operation 22 4 Programming in the User Boot Mode Page 488 2019 02 06 ...
Страница 538: ...TMPM3V6 M3V4 25 Electrical Characteristics 25 7 Recommended Oscillation Circuit Page 516 2019 02 06 ...
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