Advertisement
M16C/5L Group, M16C/56 Group
(i = 0 to 7) may also become undefined. Do not use any value in ADi registers when setting the ADST
bit to 0 by a program during A/D conversion.
24.7.7
A/D Open-Circuit Detection Assist Function
The conversion result in open-circuit depends on the external circuit. Use this function only after careful
evaluation of the system.
When A/D conversion starts after changing the AINRST register, follow these steps:
(1) Change bits AINRST1 to AINRST0 in the AINRST register.
(2) Wait for one cycle of φ AD.
(3) Set the ADST bit in the ADCON0 register to 1 (A/D conversion started).
24.7.8
Detecting Completion of A/D Conversion
In one-shot mode and single sweep mode, use the IR bit in the ADIC register to detect completion of
A/D conversion. When not using an interrupt, set the IR bit to 0 by a program after detection.
When 1 is written to the ADST bit in the ADCON0 register, the ADST bit becomes 1 (A/D conversion
start) after start processing time elapses (see Table 24.6 "Cycles of A/D Conversion Item"). Therefore
when reading the ADST bit immediately after writing 1, 0 (A/D conversion stop) may be read.
Write 1 to the ADST bit by a program.
ADST bit in the
ADCON0 register
I
R bit in the
ADIC register
Figure 24.14 ADST Bit Operation
φAD
24.7.9
Divide fAD so φ AD conforms to the standard frequency.
In particular, consider the maximum and minimum values of fOCO40M when the CKS3 bit in the
ADCON2 register is 1 (fOCO40M is fAD).
R01UH0127EJ0110 Rev.1.10
Sep 01, 2011
Start
A/D conversion
processing time
24. A/D Converter
Set to 0 by a program or
acceptance of an interrupt request.
Page 641 of 803
Advertisement
