Renesas rl78 User Manual
RL78/G1A
CHAPTER 4 PORT FUNCTIONS
R01UH0305EJ0200 Rev.2.00
113
Jul 04, 2013
4.3.9 Global digital input disable register (GDIDIS)
This register is used to prevent through-current flowing to the input buffers of input ports which use EV
DD0
as the power
supply when the EV
DD0
power supply is turned off.
When not all of the I/O ports using EV
DD0
as the power supply are used, low power consumption can be achieved by
setting the GDIDIS register (to 1) to turn off the EV
DD0
power supply.
By setting the GDIDIS0 bit to 1, input to any input buffer using EV
DD0
as the power supply is prohibited, preventing
through-current from flowing when the EV
DD0
power supply is turned off.
The GDIDIS register can be set by a 1-bit or 8-bit memory manipulation instruction.
Reset signal generation sets this register to 00H.
Remark GDIDIS register is equipped with 64-pin products.
Figure 4-9. Format of Global Digital Input Disable Register (GDIDIS)
Address: F007DH After reset: 00H R/W
Symbol
7 6 5 4 3 2 1 0
GDIDIS
0 0 0 0 0 0 0
GDIDIS0
GDIDIS0
Setting of input buffers using EV
DD0
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 EV
DD0
power supply with the following procedure.
<1> Prohibit input to input buffers (set GDIDIS0 = 1).
<2> Turn off the EV
DD0
power supply.
Turn on again the EV
DD0
power supply with the following procedure.
<1> Turn on the EV
DD0
power supply.
<2> Permit input to input buffers (set GDIDIS0 = 0).
Cautions 1. Do not input an input voltage equal to or greater than EV
DD0
to an input port that uses EV
DD
as the
power supply.
2. When input to input buffers is prohibited (GDIDIS0 = 1), the value read from the port register (Pxx)
of a port that uses EV
DD0
as the power supply is 1. When 1 is set in the port output mode register
(POMxx) (N-ch open drain output (EV
DD0
tolerance)), the value read from the port register (Pxx) is
0.
Remark Even when input to input buffers is prohibited (GDIDIS0 = 1), peripheral functions which do not use port
functions having EV
DD0
as the power supply can be used.
<R>
<R>
<R>
<R>
<R>
<R>
<R>
<R>