Chapter 4 Summary Of Programming Points - Epson E0C6001 Technical Manual

E0C6001 TECHNICAL SOFTWARE
CHAPTER 4
• Core CPU
• Power Supply
• Data Memory
• Initial Reset
II-50
SUMMARY OF PROGRAMMING
POINTS
After the system reset, only the program counter (PC),
new page pointer (NPP) and interrupt flag (I) are initial-
ized by the hardware. The other internal circuits whose
settings are undefined must be initialized with the pro-
gram.
External load driving through the output voltage of
constant voltage circuit or voltage booster/reducer is not
permitted.
– Since some portions of the RAM are also used as stack
area during sub-routine call or register saving, see to it
that the data area and the stack area do not overlap.
– The stack area consumes 3 words during a sub-routine
call or interrupt.
– Address 00H–0FH in the RAM is the memory register
area addressed by the register pointer RP.
– Memory is not mounted in unused area within the mem-
ory map and in memory area not indicated in this man-
ual. For this reason, normal operation cannot be assured
for programs that have been prepared with access to
these areas.
– Maintain the initial reset circuit at high level for at least
4 seconds (in case of oscillation frequency fosc = 32 kHz)
because noise rejector is built-in.
– When utilizing the simultaneous high input reset func-
tion of the input ports (K00–K03), take care not to make
the ports specified during normal operation to go high
simultaneously.