M32C83T datasheet(211/527 Pages) RENESAS

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16. Serial I/O (UART)

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16.2 Clock Asynchronous Serial I/O (UART) Mode

In UART mode, data is transmitted and received after setting a desired bit rate and data transfer format.

Table 16.6 lists specifications of UART mode.

Table 16.6 UART Mode Specifications

Item

Specification

Transfer Data Format

• Character bit (transfer data ) : selected from 7 bits, 8 bits, or 9 bits long

• Start bit: 1 bit long

• Parity bit: selected from odd, even, or none

• Stop bit: selected from 1 bit or 2 bits long

Transfer Clock

• The CKDIR bit in the UiMR register is set to "0" (internal clock selected) :

fj/16(m+1) fj = f1, f8, f2n(1)

m: setting value of the UiBRG register 0016 to FF16

• The CKDIR bit is set to "1" (external clock selected) :

fEXT/16(m+1)

fEXT: clock applied to the CLKi pin

Transmit/Receive Control

_______

_______ _______

• Select from CTS function, RTS function or CTS/RTS function disabled

Transmit Start Condition

• To start transmitting, the following requirements must be met:

- Set the TE bit in the UiC1 register to "1" (transmit enable)

- Set the TI bit in the UiC1 register to "0" (data in the UiTB register)

_______

- Apply an "L" signal to the CTSi pin when the CTS function is selected

Receive Start Condition

• To start receiving, the following requirements must be met:

- Set the RE bit in the UiC1 register to "1" (receive enable)

- The start bit is detected

Interrupt Request

• Transmit interrupt timing can be selected from the followings:

Generation Timing

- The UiIRS bit in the UiC1 register is set to "0" (no data in the transmit buffer) :

when data is transferred from the UiTB register to the UARTi transmit register (transfer started)

- The UiIRS bit is set to "1" (transmission completed) :

when data transmission from the UARTi transfer register is completed

• Receive interrupt timing

when data is transferred from the UARTi receive register to the UiRB register (reception completed)

Error Detect

• Overrun error(2)

This error occurs when the bit before the last stop bit of the next received data is read

prior to reading the UiRB register (the first stop bit when selecting 2 stop bits)

• Framing error

This error occurs when the number of stop bits set is not detected

• Parity error

When parity is enabled, this error occurs when the number of "1" in parity and character

bits does not match the number of "1" set

• Error sum flag

This flag is set to "1" when any of an overrun, framing or parity errors occur

Selectable Function

• LSB first / MSB first

Data is transmitted or received in either bit 0 or in bit 7

•Serial data logic inverse

Logic values of data to be transmitted or received data are inversed. The start bit and

stop bit are not inversed

•TxD, RxD I/O polarity switching

TxD pin output and RxD pin input are inversed

NOTES:

1. The CNT3 to CNT0 bits in the TCSPR register select no division (n=0) or divide-by-2n (n=1 to 15).

2. If an overrun error occurs, the UiRB register is indeterminate. The IR bit in the SiRIC register remains unchanged

as "1" (interrupt requested).

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