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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 AVDD as the
power supply when the AV
DD power supply is turned off.
When not all of the I/O ports using AV
DD as the power supply are used, low power consumption can be achieved by
setting the GAIDIS register (to 1) to turn off the AVDD power supply.
By setting the GAIDIS0 bit to 1, input to any input buffer using AV
DD as the power supply is prohibited, preventing
through-current from flowing when the AV
DD power supply is turned off.
When using the GAIDIS register, set the GAIDIS0 bit to 1 while the AVDD voltage is 1.6 V or higher, and then reduce
the AV
DD voltage to 0 V.
Set GAIDIS0 to 0 after applying power to AV
DD.
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
GAIDIS0 Setting of input buffers using AVDD power supply
0 Input to input buffers permitted (default)
1 Input to input buffers prohibited. No through-current flows to the input buffers.
Turn off the AVDD power supply with the following procedure.
<1> Prohibit input to input buffers (set GAIDIS0 = 1).
<2> Turn off the AV
DD power supply.
Turn on again the AVDD power supply with the following procedure.
<1> Turn on the AVDD 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
DD to an input port that uses AVDD 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
DD 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
DD as the power supply can be used.
<R>
<R>
<R>
<R>
<R>
<R>
<R>
<R>