NEC mPD780344 Series User Manual page 108

(2) Pull-up resistor option registers (PU0, PU2 to PU4)
These registers are used to set whether to use an on-chip pull-up resistor at each port or not in 1-bit units. By
setting PU0 and PU2 to PU4, the on-chip pull-up resistors of the port pins corresponding to the bits in PU0 and
PU2 to PU4 can be used.
PU0 and PU2 to PU4 are set by a 1-bit or 8-bit memory manipulation instruction.
RESET input sets the values of these registers to 00H.
Cautions 1. The P10 to P17 pins do not incorporate a pull-up resistor.
2. The P70 to P73 pins can be used with a pull-up resistor by setting a mask option only for
mask ROM versions.
3. The P30 and P31 pins can be used with a pull-up resistor by setting a mask option only
for mask ROM versions of the µ PD780344, 780354 Subseries.
4. When PUm is set to 1, an on-chip pull-up resistor is connected irrespective of the input/
output mode. When using the port in output mode, therefore, set the corresponding bits
of PUm to 0 (m = 0, 2 to 4).
Figure 4-19. Format of Pull-Up Resistor Option Registers (PU0, PU2 to PU4)
Address: FF30H After reset: 00H
Symbol 7
PU0 PU07
Address: FF32H After reset: 00H
Symbol 7
PU2 PU27
Address: FF33H After reset: 00H
Symbol 7
PU3 0
Address: FF34H After reset: 00H
Symbol 7
PU4 0
PUmn
0
1
108
CHAPTER 4 PORT FUNCTIONS
R/W
6 5
PU06 PU05 PU04
R/W
6 5
PU26 PU25 PU24
R/W
6 5
0 PU35 PU34
R/W
6 5
0 0
Pmn pin internal pull-up resistor selection (m = 0, 2 to 4: n = 0 to 7)
On-chip pull-up resistor not used
On-chip pull-up resistor used
User's Manual U15798EJ2V0UD
4 3 2
PU03 PU02
4 3 2
PU23 PU22
4 3 2
PU33 PU32
4 3 2
0 PU43 PU42
1 0
PU01 PU00
1 0
PU21 PU20
1 0
0 0
1 0
PU41 PU40