Datasheet

CHAPTER 12 10-BIT SUCCESSIVE APPROXIMATION TYPE A/D CONVERTER ( μ PD78F041x only)
User’s Manual U18698EJ1V0UD
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(8) 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 for the
pre-change analog input may be set just before the ADS rewrite. Caution is therefore required since, at this time,
when ADIF is read immediately after the ADS rewrite, ADIF 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 before the A/D conversion operation is resumed.
Figure 12-21. 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.
Remarks 1. n = 0 to 5
2. m = 0 to 5
(9) Conversion results just after A/D conversion start
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 1
μ s after the ADCE bit was set to 1, or if the ADCS bit is set to 1 with the ADCE bit =
0. Take measures such as polling the A/D conversion end interrupt request (INTAD) and removing the first
conversion result.
(10) A/D conversion result register (ADCR, ADCRH) read operation
When a write operation is performed to the A/D converter mode register (ADM), analog input channel
specification register (ADS), and A/D port configuration register 0 (ADPC0), the contents of ADCR and ADCRH
may become undefined. Read the conversion result following conversion completion before writing to ADM,
ADS, and ADPC0. Using a timing other than the above may cause an incorrect conversion result to be read.