A/D Converter Operation Modes; Interrupts; Typical Use - Renesas H8 Series Hardware Manual

8-bit single-chip microcomputer

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A/D Converter Operation Modes

A/D converter operation modes are shown in table 12.3.

Table 12.3 A/D Converter Operation Modes

Retained * Functions Functions Retained Retained Retained Retained Retained

Retained * Functions Functions Retained Retained Retained Retained Retained

Note: * Undefined in a power-on reset.

When A/D conversion ends (ADSF changes from 1 to 0), bit IRRAD in interrupt request register 2

(IRR2) is set to 1.

A/D conversion end interrupts can be enabled or disabled by means of bit IENAD in interrupt

enable register 2 (IENR2).

For further details see section 3.3, Interrupts.

An example of how the A/D converter can be used is given below, using channel 1 (pin AN1) as

the analog input channel. Figure 12.3 shows the operation timing.

1. Bits CH3 to CH0 of the A/D mode register (AMR) are set to 0101, making pin AN

input channel. A/D interrupts are enabled by setting bit IENAD to 1, and A/D conversion is

started by setting bit ADSF to 1.

2. When A/D conversion is complete, bit IRRAD is set to 1, and the A/D conversion result is

stored in ADRRH and ADRRL. At the same time ADSF is cleared to 0, and the A/D converter

goes to the idle state.

3. Bit IENAD = 1, so an A/D conversion end interrupt is requested.

4. The A/D interrupt handling routine starts.

5. The A/D conversion result is read and processed.

6. The A/D interrupt handling routine ends.

Functions Functions Retained Retained Retained Retained Retained

Rev. 7.00 Mar 10, 2005 page 407 of 652

Section 12 A/D Converter

REJ09B0042-0700