Clock Asynchronous Serial I/O (Uart) Mode - Renesas M16C/60 Series Hardware Manual

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M16C/6N5 Group

Clock Asynchronous Serial I/O (UART) Mode

The UART mode allows transmitting and receiving data after setting the desired transfer rate and transfer
data format. Tables 1.15.5 lists the specifications of the UART mode. Table 1.15.6 lists the registers used
in UART mode and the register values set.
Table 1.15.5 UART Mode Specifications
Item
Transfer data format
Transfer clock
Transmission, reception control
Transmission start condition
Reception start condition
Interrupt request
generation timing
Error detection
Select function
i = 0 to 2
Note 1: The U0IRS and U1IRS bits respectively are the UCON register bits 0 and 1; the U2IRS bit is the U2C1 register bit 4.
Note 2: If an overrun error occurs, the value of UiRB register will be indeterminate. The IR bit of SiRIC register does not change.
Rev.1.00 2003.05.30 page 149
• Character bit (transfer data): Selectable from 7, 8 or 9 bits
• Start bit: 1 bit
• Parity bit: Selectable from odd, even, or none
• Stop bit: Selectable from 1 or 2 bits
• UiMR register's CKDIR bit = 0 (internal clock) : fj/ 16(n+1)
fj = f , f , f , f . n: Setting value of UiBRG register
1SIO 2SIO 8SIO 32SIO
• CKDIR bit = 1 (external clock) : f
f : Input from CLKi pin.
EXT
_______
• Selectable from CTS function, RTS function or CTS/RTS function disabled
• Before transmission can start, the following requirements must be met
_
The TE bit of UiC1 register = 1 (transmission enabled)
_
The TI bit of UiC1 register = 0 (data present in UiTB register)
_______
_
If CTS function is selected, input on the CTSi pin = L
• Before reception can start, the following requirements must be met
_
The RE bit of UiC1 register = 1 (reception enabled)
_
Start bit detection
• For transmission, one of the following conditions can be selected
_
The UiIRS bit (Note 1) = 0 (transmit buffer empty): when transferring data from the
UiTB register to the UARTi transmit register (at start of transmission)
_
The UiIRS bit =1 (transfer completed): when the serial I/O finished sending data from
the UARTi transmit register
• For reception
When transferring data from the UARTi receive register to the UiRB register (at
completion of reception)
• Overrun error (Note 2)
This error occurs if the serial I/O started receiving the next data before reading the
UiRB register and received the bit one before the last stop bit of the next data
• Framing error
This error occurs when the number of stop bits set is not detected
• Parity error
This error occurs when if parity is enabled, the number of 1's in parity and character
bits does not match the number of 1's set
• Error sum flag
This flag is set to "1" when any of the overrun, framing, and parity errors is encountered
• LSB first, MSB first selection
Whether to start sending/receiving data beginning with bit 0 or beginning with bit 7
can be selected
• Serial data logic switch
This function reverses the logic of the transmit/receive data. The start and stop bits
are not reversed.
• T D, R D I/O polarity switch
X X
This function reverses the polarities of the T
logic levels of all I/O data is reversed.
_______ _______
• Separate CTS/RTS pins (UART0)
_________ _________
CTS and RTS are input/output from separate pins
0 0
Specification
/16(n+1)
EXT
n :Setting value of UiBRG register
_______ _______ _______
_______
D pin output and R
X
Serial I/O (UART Mode)
00 to FF
16 16
00 to FF
16 16
D pin input. The
X