R5F72115D160FPV datasheet(813/1228 Pages) RENESAS

813 / 1228 page

Section 17 A/D Converter (ADC)

Rev. 2.00 May. 08, 2008 Page 789 of 1200

REJ09B0344-0200

When the ACE bit is 0 (initial value) and the A/D conversion result (H'0222) is not written to

ADDR for some reason, the old data (H'0111) becomes the ADDR value. In addition, when the

ADDR value is read into a general register using an A/D conversion end interrupt, the old data

(H'0111) is stored in the general register. To detect a renewal failure, every time the old data needs

to be stored in the RAM, a general register, etc.

When the ACE bit is 1, reading ADDR

= H'0111 by the CPU or DMAC automatically clears

ADDR to H'0000. After this, if the A/D conversion result (H'0222) cannot be transferred to

ADDR for some reason, the cleared data (H'0000) remains as the ADDR value. When this ADDR

value is read into a general register, H'0000 is stored in the general register. Just by checking

whether the read data value is H'0000 or not allows the detection of non-updated ADDR states.

A/D conversion result

• ACE bit = 0 (Normal condition: Auto-clear function is disabled.)

• ACE bit = 1 (Auto-clear function is enabled.)

A/D data register (ADDR)

A/D conversion end interrupt

RAM, general register etc.

H'0111

H'0222

H'0333

H'0444

ADDR renewal failure

Read

Because ADDR is not renewed, old data is used.

However, it is impossible to know that the data is old or not.

Automatic clearing

after read

When H'0000 is read, a failure is detected by software.

H'0111

H'0000

H'0333

H'0111

H'0000

H'0333

H'0000

A/D data register (ADDR)

A/D conversion end interrupt

RAM, general register etc.

H'0111

H'0222

H'0333

H'0444

ADDR renewal failure

Read

H'0111

H'0333

H'0111

H'0333

Automatic clearing

after read

Automatic clearing

after read

Figure 17.6 Example of When ADDR Auto-clear Function is

Disabled (Normal Condition)/Enabled

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