2.17 Power Management

2.17.1 Sleep

By specification, Nintendo 3DS systems require more stringent power-saving measures than past portable devices. Consequently, Nintendo recommends transitioning all processing to sleep when the system is closed unless there are specific reasons not to. If processing cannot be transitioned immediately to sleep mode, applications can return REPLY_LATER as the response to a sleep request when the system is closed, and transition to sleep mode once processing has completed. If there is some game specification-related reason that prevents transitioning to sleep mode right as the system is being closed, deny the sleep request.

Be aware that there are restrictions for transitioning to Sleep Mode. These are described in section 3.4.2 Sleep Requests While Writing Data.

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2.17.2 Active Backlight

The Nintendo 3DS System Settings include an option to enable an active backlight. This feature reduces battery consumption by adjusting the strength of the backlight to match the overall screen brightness. Users can enable or disable the active backlight from the brightness control screen on the HOME Menu. The active backlight is disabled by default, but Nintendo expects that a lot of users will play with the active backlight enabled, depending on how the Nintendo 3DS system is used.

Depending on what the application is displaying, there may be times when contrast declines and text becomes hard to read if the active backlight is enabled, even though the same content displays correctly when the active backlight is disabled.

Moreover, when the active backlight is enabled, it will sometimes adjust the backlight strength up and down in response to changes in image brightness that are too small for the human eye to discern. As a result, if you have two images that look the same at first glance but have slightly different levels of brightness, and you want to display them alternately and have it look like a still image, this sometimes produces a flickering effect if the active backlight is enabled. When the Nintendo 3DS active backlight is enabled, this flickering is most prominent when the screen brightness is set to 1.


Given these considerations, we recommend that you play through all modes of the application from beginning to end to verify performance when the active backlight is enabled and screen brightness set to 1.

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