UPD78F9234MC-5A4-A Datasheet, PDF (392/419 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

APPENDIX D LIST OF CAUTIONS
This appendix lists cautions described in this document.
“Classification (hard/soft)” in table is as follows.
Hard: Cautions for microcontroller internal/external hardware
Soft: Cautions for software such as register settings or programs
Function
Details of
Function
Cautions
(1/20)
Page
Pin
configu-
ration
Pin
functions
Memory
space
Port
functions
AVSS pin
Connect the AVSS pin to VSS.
p.16
P121/X1 and
P122/X2 pins
The P121/X1 and P122/X2 pins are pulled down during reset.
pp.
21, 22,
24, 25
Vector table
No interrupt sources correspond to the vector table address 0014H.
p.30
address
SP: Stack pointer Since generation of reset signal makes the SP contents undefined, be sure to p.34
initialize the SP before using the stack memory.
Stack pointers can be set only to the high-speed RAM area, and only the lower p.34
10 bits can be actually set. Thus, if the stack pointer is specified to 0FF00H, it
is converted to 0FB00H in the high-speed RAM area, since 0FF00H is in the
SFR area and not in the high-speed RAM area.
When the value is actually pushed onto the stack, 1 is subtracted from
0FB00H to become 0FAFFH, but since that value is not in the high-speed
RAM area, it is converted to 0FEFFH, which is the same value as when
0FF00H is set to the stack pointer.
P121/X1 and
The P121/X1 and P122/X2 pins are pulled down during reset.
p.53
P122/X2 pins
P34 pin
Because the P34 pin functions alternately as the RESET pin, if it is used as an p.59
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 18 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.
P30, P31, and
P43 pins
Because P30, P31, and P43 are also used as external interrupt pins, the
p.67
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.
PMC: Port mode When PMC20 to PMC23 are set to 1, the P20/ANI0 to P23/ANI3 pins cannot p.69
control register 2 be used as port pins. Moreover, be sure to set the pull-up resistor option
registers (PU20 to PU23) to 0 for the pins set to A/D converter mode.
−
Although a 1-bit memory manipulation instruction manipulates 1 bit, it
p.71
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.
390
User’s Manual U17446EJ5V0UD