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RL78/D1A User's Manual: Hardware - Renesas

RL78/D1A User's Manual: Hardware - Renesas

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Under development<br />

Preliminary document<br />

Specifications in this document are tentative and subject to change.<br />

<strong>RL78</strong>/<strong>D1A</strong> CHAPTER 25 SAFETY FUNCTIONS<br />

25.3.8 A/D test function<br />

The IEC60730 standard mandates testing the A/D converter. The A/D test function is used to check whether the A/D<br />

converter is operating normally by executing A/D conversions of the AVREF voltage.<br />

The analog multiplexer can be checked using the following procedure.<br />

(1) Perform A/D conversion for the ANIx pin (conversion result 1).<br />

(2) Select AVREFM using the ADTES register, perform A/D conversion, and then set the voltage potential difference<br />

between the terminals of the sampling capacitor of the A/D converter to 0 V.<br />

(3) Perform A/D conversion for the ANIx pin (conversion result 2).<br />

(4) Select AVREFP using the ADTES register, perform A/D conversion, and then set the voltage potential difference<br />

between the terminals of the sampling capacitor of the A/D converter to AVREF.<br />

(5) Perform A/D conversion for the ANIx pin (conversion result 3).<br />

(6) Make sure that conversion results 1, 2, and 3 are equal.<br />

Using the procedure above can confirm that the analog multiplexer is selected and all wiring is connected.<br />

Remarks 1. If the analog input voltage is variable during A/D conversion in steps to above, use<br />

another method to check the analog multiplexer.<br />

2. The conversion results might contain an error. Consider an appropriate level of error when<br />

comparing the conversion results.<br />

ANI0/AVREFP<br />

ANI1/AVREFM<br />

ANIx<br />

ANIx<br />

Figure 25-15. Configuration of A/D Test Function<br />

VDD<br />

VSS<br />

A/D convertor<br />

+ side reference<br />

voltage source<br />

(AVREF+)<br />

- side reference<br />

voltage source<br />

(AVREF-)<br />

R01UH0317EJ0004 Rev. 0.04 1149<br />

Feb. 22, 2013

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