M16C6K9 Datasheet, PDF (119/292 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

M16C/6K9 Group
Clock asynchronous serial I/O (UART) mode
• Example of receive timing when transfer data are 8 bits long (parity disabled, one stop bit)
BRGi count
source
“1”
Receive enable bit _{“0”}
RxDi
Start bit
Stop bit
D0
D1 D7
Sampled “L”
Receive data taken in
Transfer clock
Receive
complete flag
RTSi
Receive interrupt
request bit
Reception triggered when transfer clock
“1” _{is generated by falling edge of start bit}
“0”
“H”
“L”
“1”
“0”
Transferred from UARTi receive register to
UARTi receive buffer register
Cleared to “0” when interrupt request is accepted, or cleared by software
The above timing applies to the following settings :
•Parity is disabled.
•One stop bit.
•RTS function is selected.
Fig.GA-18 Typical receive timing in UART mode
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(a) Separate CTS/RTS pins function (UART0)
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Setting the CTS/RTS separate bit (bit 6 of address 03B016) to "1" separates the RTS and CTS signals to
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different input/out pins.(Fig GA-19). Choosing one from CTS or RTS, by using of the CTS/RTS function
selection bit (bit 2 of address 03A416). This function is effective in UART0 only. If the function is used, the
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user cannot use the CTS/RTS function of UART1. Set "0" both to the CTS/RTS function selection bit (bit 2 of
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address 03AC16) and to the CTS/RTS disable bit (bit 4 of address 03AC16).
Microcomputer
TXD0
RXD0
IC
IN
OUT
RTS0
CTS0
CTS
RTS
Note : The user cannot use CTS and RTS at the same time.
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Fig.GA-19 The separate CTS/RTS pins function usage
(b) Sleep mode (UART0, UART1)
This mode is used to transfer data between specific microcomputers among multiple microcomputers con-
nected with UARTi. The sleep mode is selected when the sleep selection bit (bit 7 at addresses 03A016,
03A816) is set to “1” during reception. In this mode, the unit performs receive operation when the MSB of the
received data = “1” and does not perform receive operation when the MSB = “0”.
Rev.1.00 Jun 06, 2003 page 119 of 290