CMS32L051 User Manual |Chapter 24 Security Features
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24.3.6 A/D test function
The IEC60730 standard requires testing of A/D converters. This A/D test function is performed with
a positive (+) reference voltage for the A/D converter, a negative () reference, an analog input channel
(ANI), an output voltage for a temperature sensor, and an internal reference A/D conversion to confirm
that the A/D converter is operating properly.
The analog multiplexer can be verified by following these steps:
① The ANIx pin is selected as the A/D conversion object through the ADTES register (ADTES2,
ADTES1, ADTES0=0, 0, 0).
② A/D conversion of the ANIx pin (conversion result 1-1).
③ The negative () reference voltage of the A/D converter is selected as the A/D conversion object
through the ADTES register (ADTES2, ADTES1, ADTES0=0, 0, 1).
④ A/D conversion of the negative () reference voltage of the A/D converter (results 2-1).
⑤ The ANIx pin is selected as the A/D conversion object through the ADTES register (ADTES2,
ADTES1, ADTES0=0, 0, 0).
⑥ A/D conversion of the ANIx pin (conversion results 1-2).
⑦ The positive (+) reference voltage of the A/D converter is selected from the ADTES register as
the A/D conversion object (ADTES2, ADTES1, ADTES0=1, 0, 1).
⑧ A/D conversion of the positive (+) reference voltage of the A/D converter (conversion results 2-
2).
⑨ The ANIx pin is selected as the A/D conversion object through the ADTES register (ADTES2,
ADTES1, ADTES0=0, 0 , 0).
⑩ A/D conversion of the ANIx pin (conversion result 1-3).
⑪ Verify that the Conversion Results 1-1, Conversion Results 1-2, and Conversion Results 1-3 are
the same.
⑫ Confirm that the A/D conversion result of Conversion Result 2-1 is all 0 and the A/D of
Conversion Result 2-2 The result of the conversion is all 1. With these steps, you can select
an analog multiplexer and verify that the wiring is not broken.
Note 1 During the conversion of (1) to (10), if the analog input voltage is variable, other methods must be used to confirm
the analog multiplexer.
2. The conversion result contains errors, so the error must be properly considered when comparing the conversion results.
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