Rev.1.02 Jul 01, 2005 page 298 of 314
REJ09B0126-0102
M16C/6N Group (M16C/6NL, M16C/6NN) 22. Usage Precaution
Under development
This document is under development and its contents are subject to change.
If the CPU reads the ADi register at the same time the conversion result is stored in the ADi register after
completion of A/D conversion, an incorrect value may be stored in the ADi register. This problem occurs
when a divide-by-n clock derived from the main clock or a sub clock is selected for CPU clock.
•When operating in one-shot or single-sweep mode
Check to see that A/D conversion is completed before reading the target ADi register. (Check the IR bit in
the ADIC register to see if A/D conversion is completed.)
•When operating in repeat mode or repeat sweep mode 0 or 1
Use the main clock for CPU clock directly without dividing it.
If A/D conversion is forcibly terminated while in progress by setting the ADST bit in the ADCON0 register to
“0” (A/D conversion halted), the conversion result of the A/D converter is indeterminate. The contents of ADi
registers irrelevant to A/D conversion may also become indeterminate. If while A/D conversion is underway
the ADST bit is set to “0” in a program, ignore the values of all ADi registers.
When setting the ADST bit to “0” in single sweep mode during A/D conversion and A/D conversion is
aborted, disable the interrupt before setting the ADST bit to “0”.