UPD78F9502MA-CAC-A NEC, UPD78F9502MA-CAC-A Datasheet - Page 222

• Manufacturer Part Number: UPD78F9502MA-CAC-A
• Description: 8BIT MCU, 4K FLASH, 128B RAM, SMD
• Manufacturer: NEC

Specifications of UPD78F9502MA-CAC-A

• Controller Family/series: UPD78F
• No. Of I/o's: 8
• Ram Memory Size: 128Byte
• Cpu Speed: 10MHz
• No. Of Timers: 2
• No. Of Pwm: RoHS Compliant
• Core Size: 8bit
• Program Memory Size: 4KB
• Oscillator Type: External, Internal

222
This appendix lists cautions described in this document.
“Classification (hard/soft)” in table is as follows.
Hard:
Soft:
Pin
functions
Memory
space
Port
functions
8-bit timer
H1
Function
Cautions for microcontroller internal/external hardware
Cautions for software such as register settings or programs
P22,
P23/X1/ANI3,
P34/RESET
SP: stack
pointer
P22,
P23/X1/ANI3,
P34/RESET
P34
P21, P32
CMP01: 8-bit
timer H
compare
register 01
Details of
Function
The P22 and P23/EXCLK pins are pulled down during reset. The P34/RESET
pin is pulled up during reset by the reset pin function/power-on clear circuit.
Since reset signal generation makes the SP contents undefined, be sure to
initialize the SP before using the stack memory.
Stack pointers can be set only to the high-speed RAM area, and only the lower
10 bits can be actually set.
0FF00H is in the SFR area, not the high-speed RAM area, so it was converted
to 0FB00H that is in the high-speed RAM area. When the value is actually
pushed onto the stack, 1 is subtracted from 0FB00H to become 0FAFFH, but
that value is not in the high-speed RAM area, so it is converted to 0FEFFH,
which is the same value as when 0FF00H is set to the stack pointer.
The P22 and P23/EXCLK pins are pulled down during reset. The P34/RESET
pin is pulled up during reset by the reset pin function/power-on clear circuit.
Because the P34 pin functions alternately as the RESET pin, if it is used as an
input port pin, the function to input an external reset signal to the RESET pin
cannot be used. The function of the port is selected by the option byte. For
details, refer to CHAPTER 13 OPTION BYTE.
Also, since the option byte is referenced after the reset release, if low level is
input to the RESET pin before the referencing, then the reset state is not
released. When it is used as an input port pin, connect the pull-up resistor.
Because P21 and P32 are also used as external interrupt pins, the
corresponding interrupt request flag is set if each of these pins is set to the
output mode and its output level is changed. To use the port pin in the output
mode, therefore, set the corresponding interrupt mask flag to 1 in advance.
Although a 1-bit memory manipulation instruction manipulates 1 bit, it accesses
a port in 8-bit units. Therefore, the contents of the output latch of a pin in the
input mode, even if it is not subject to manipulation by the instruction, are
undefined in a port with a mixture of inputs and outputs.
CMP01 cannot be rewritten during timer count operation.
APPENDIX C LIST OF CAUTIONS
Preliminary User’s Manual U18681EJ1V0UD
Cautions
21
pp. 19-
p. 32
p. 32
p. 48
p. 54
p. 56
p. 59
p. 74
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