H8SXSLASH1663R datasheet(1124/1504 Pages) RENESAS

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Section 22 A/D Converter

Rev. 2.00 Sep. 24, 2008 Page 1092 of 1468

REJ09B0412-0200

22.7

Usage Notes

22.7.1

Module Stop Function Setting

Operation of the A/D converter can be disabled or enabled using the module stop control register.

The initial setting is for operation of the A/D converter to be halted. Register access is enabled by

clearing the module stop state. Set the CKS1 and CKS2 bits to 1 and clear the ADST, TRGS1,

TRGS0, and EXTRGS bits all to 0 to disable A/D conversion when entering module stop state

after operation of the A/D converter. After that, set the module stop control register after executing

a dummy read by one word. For details, see section 28, Power-Down Modes.

22.7.2

A/D Input Hold Function in Software Standby Mode

When this LSI enters software standby mode with A/D conversion enabled, the analog inputs are

retained, and the analog power supply current is equal to as during A/D conversion. If the analog

power supply current needs to be reduced in software standby mode, set the CKS1 and CKS2 bits

to 1 and clear the ADST, TRGS1, TRGS0, and EXTRGS bits all to 0 to disable A/D conversion.

After that, enter software standby mode after executing a dummy read by one word.

22.7.3

Notes on A/D Activation by an External Trigger

If any of actions (1 to 3 below) is performed while activation by an external trigger* is in use,

stopping A/D conversion may be impossible.

Note: * External trigger refers to input on the ADTRG pin or the conversion trigger from a

peripheral module (TMR or TPU).

1. When the setting for activation by an external trigger is in use, writing to change the value of

the ADST bit in ADCSR from 0 to 1.

2. Changing the setting from activation by an external trigger to prohibition of external triggers.

3. Changing the scan mode (SCANE and ADSTLCR bits; from continuous scan mode to single

mode or single-cycle scan mode) while the setting is for activation by an external trigger.

If any of the above points apply, make the corresponding settings listed below.

If point 1 is applicable

Do not perform writing to change the value of the ADST bit in ADCSR from 0 to 1 when the

setting for activation by an external trigger is in use.

If points 2 or 3 is applicable

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