Renesas rl78 User Manual

RL78/G1A

CHAPTER 4 PORT FUNCTIONS

R01UH0305EJ0200 Rev.2.00

114

Jul 04, 2013

4.3.10 Global analog input disable register (GAIDIS)

This register is used to prevent through-current flowing from the input buffers of input ports which use AV

as the

power supply when the AV

power supply is turned off.

When not all of the I/O ports using AV

as the power supply are used, low power consumption can be achieved by

setting the GAIDIS register (to 1) to turn off the AV

power supply.

By setting the GAIDIS0 bit to 1, input to any input buffer using AV

as the power supply is prohibited, preventing

through-current from flowing when the AV

power supply is turned off.

When using the GAIDIS register, set the GAIDIS0 bit to 1 while the AV

voltage is 1.6 V or higher, and then reduce

the AV

voltage to 0 V.

Set GAIDIS0 to 0 after applying power to AV

The GAIDIS register can be set by a 1-bit or 8-bit memory manipulation instruction.

Reset signal generation sets this register to 00H.

Figure 4-10. Format of Global Analog Input Disable Register (GAIDIS)

Address: F007CH After reset: 00H R/W

Symbol

7 6 5 4 3 2 1 0

GAIDIS

0 0 0 0 0 0 0

GAIDIS0

Setting of input buffers using AV

power supply

Input to input buffers permitted (default)

Input to input buffers prohibited. No through-current flows to the input buffers.

Turn off the AV

power supply with the following procedure.

<1> Prohibit input to input buffers (set GAIDIS0 = 1).

<2> Turn off the AV

power supply.

Turn on again the AV

power supply with the following procedure.

<1> Turn on the AV

power supply.

<2> Permit input to input buffers (set GAIDIS0 = 0).

Cautions 1. Do not input an input voltage equal to or greater than AV

to an input port that uses AV

as the

power supply.

2. When input to input buffers is prohibited (GAIDIS0 = 1), the value read from the port register (Pxx)

of a port that uses AV

as the power supply is 1.

Remark Even when input to input buffers is prohibited (GAIDIS0 = 1), peripheral functions which do not use port

functions having EV

as the power supply can be used.

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