M32CSLASH8B datasheet(297/406 Pages) RENESAS

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M32C/8B Group

22. Programmable I/O Ports

Preliminary specification

Specifications in this manual are tentative and subject to change.

REJ09B0450-0050 Rev.0.50 Oct 31, 2008

Page 280 of 385

22.6

Pull-up Control Register 0 to 4 (PUR0 to PUR4 Registers)

Figures 22.12 to 22.15 show registers PUR0 to PUR4.

Registers PUR0 to PUR4 select whether the ports, divided into groups of four, are pulled up or not. Set the bit in

registers PUR0 to PUR4 to 1 (pull-up) and the bit in the PDi register to 0 (input mode) to pull-up the corresponding

port.

In memory expansion mode and microprocessor mode, set bits, corresponding to the bus control pins (P0 to P5), in

registers PUR0 and PUR1 to 0 (no pull-up). P0, P1, and P4_0 to P4_3 can be pulled up when they are used as input

ports in memory expansion mode and microprocessor mode.

22.7

Port Control Register (PCR Register)

Figure 22.16 shows the PCR register.

The PCR register selects either CMOS output or N-channel open drain output as port P1 output format. When the

PCR0 bit is set to 1, P channel in the CMOS port is turned off at all times and in result port P1 becomes N-channel

open drain output. This is, however, pseudo open drain. Therefore, the absolute maximum rating of the input

voltage is from -0.3 V to VCC2 + 0.3 V.

To use port P1 as data bus in memory expansion mode and microprocessor mode, set the PCR0 bit to 0 (CMOS

output). When port P1 is used as a port in memory expansion mode and microprocessor mode, set the output format

using the PCR0 bit.

22.8

Analog Input and Other Peripheral Function Input

Bits PSL3_3 to PSL3_6 in the PSL3 register, and the PSC_7 bit in the PSC register are used to separate peripheral

function inputs from analog input/output. If the analog I/O shares the pin with other peripheral function inputs, a

through current may flow to the peripheral function inputs when an intermediate voltage is applied to the pin.

To use the analog I/O (DA0, DA1, ANEX0, ANEX1, or AN_4 to AN_7), set the corresponding bit to 1 (analog I/

O), and disconnect the peripheral function inputs to prevent an intermediate voltage from being applied to the

peripheral function inputs.

For P10_4 to P10_7 (AN_4 to AN_7/KI0 to KI3), when the PSC_7 bit is set to 1, the input buffer for the peripheral

functions including the port function is disconnected and ports P10_4 to P10_7 are read as undefined. Also, the IR

bit in the KUPIC register remains unchanged as 0 (interrupt not requested) even if KI0 to KI3 pin input levels are

changed.

Set the corresponding bit to 0 (except analog I/O) when analog I/O is not used.

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