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RL78/G1A CHAPTER 11 A/D CONVERTER
R01UH0305EJ0200 Rev.2.00 398
Jul 04, 2013
(7) Interrupt request flag (ADIF)
The interrupt request flag (ADIF) is not cleared even if the analog input channel specification register (ADS) is
changed.
Therefore, if an analog input pin is changed during A/D conversion, the A/D conversion result and ADIF flag for the
pre-change analog input may be set just before the ADS register rewrite. Caution is therefore required since, at this
time, when ADIF flag is read immediately after the ADS register rewrite, ADIF flag is set despite the fact A/D
conversion for the post-change analog input has not ended.
When A/D conversion is stopped and then resumed, clear ADIF flag before the A/D conversion operation is resumed.
Figure 11-45. Timing of A/D Conversion End Interrupt Request Generation
ADS rewrite
(start of ANIn conversion)
A/D conversion
ADCR
ADIF
ANIn ANIn ANIm ANIm
ANIn ANIn ANIm ANIm
ADS rewrite
(start of ANIm conversion)
ADIF is set but ANIm conversion
has not ended.
(8) Conversion results just after A/D conversion start
While in the software trigger mode or hardware trigger no-wait mode, the first A/D conversion value immediately after
A/D conversion starts may not fall within the rating range if the ADCS bit is set to 1 within the stabilization wait time
after the ADCE bit was set to 1. Take measures such as polling the A/D conversion end interrupt request (INTAD)
and removing the first conversion result.
[Stabilization wait status]
If a high-accuracy channel is selected as the analog input channel: 0.5
μ
s
If a test mode setting (ADTES1 bit of ADTES register = 1) is selected: 0.5
μ
s
If a standard channel is selected as the analog input channel: 2
μ
s
If a temperature sensor output/internal reference voltage output are selected as the analog input channel:
(ADISS bit of ADS register = 1): 2
μ
s
(9) A/D conversion result register (ADCR, ADCRH) read operation
When a write operation is performed to A/D converter mode register 0 (ADM0), analog input channel specification
register (ADS), A/D port configuration register (ADPC), and port mode control register (PMCx), the contents of the
ADCR and ADCRH registers may become undefined. Read the conversion result following conversion completion
before writing to the ADM0, ADS, ADPC, or PMCx register. Using a timing other than the above may cause an
incorrect conversion result to be read.