M16C6K9 Datasheet, PDF (225/292 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

M16C/6K9 Group
Port
The P0, P1, P40 to P46, P11 and P14 output type, CMOS or N channel open drain, are set by bit 0 to 6 of port
control register 1 and bit 0 to 2 of port control register 3.
0 : CMOS output
1 : N channel open drain output
Exception: P42 output type is N channel open drain if either bit 4 of port control register 1 or bit 2 of port
control register 3 is set to “1”.
Bit 7 of port control register1 functions as below
0 : P40/P43 output is cleared by software only
1 : P40/P43 output is cleared by software or when output buffer 0 is read by host side.
The driving ability of N channel output transistors for P140 to P143 can be selected by bit 6 of port control
register 2 controls as below:
0 : Driving ability of N channel open drain output transistor is LOW
1 : Driving ability of N channel open drain output transistor is HIGH
(5) Port P4/P7 input register
Fig.UA-14 shows the configurations of P4 and P7 input register.
By reading the registers, the input level of the corresponding pins can be known regardless the input/output
mode.These two registers can be read regardless port direction setting. And the ports level will be read out.
Port4 : Bit 0 to bit6's level will be read out. And bit7 is always “0”.
Port7 : Bit 0 to bit5's level will be read out. And bit6,7 is always “0”.
(6) Port function selection register 0,1,2
Fig.UA-15, UA-16 shows the configurations of port function selection register 0,1,2. The port functions of
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UART0 to UART2 input/output, TimerA0 to TimerA2 output, TimerB3,B4 input or external interrupt INT6 to
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INT12 input can be switched by setting these two registers. By setting bit0,1 of port function selection regis-
ter 2, the same frequency clock with f(XIN) can be output from P110 and P111.
Rev.1.00 Jun 06, 2003 page 225 of 290