H2 image

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H2 - Operation
With its default software, the H2 can function as an ebook or as a slideshow viewer. The mode is selected from a boot up title screen, which the user can return to from inside either mode. Both modes show the same image set from the MMC card; with only the way image transitions are initiated differing between modes. The image set can be changed by removing the MMC card and altering its contents, or by transferring content to and from the card using one of the communications interfaces. The operation of the book can be changed by editing the shell scripts which control its behaviour, or by writing and installing entirely different software.

Power Up
With the alkaline model, the battery tube cap is screwed in until the Tx LED visible through the back or side of the case begins to flash. With the Li model, the battery cutout switch is slid to the on position.

Boot up takes about 10 seconds at this point, which can hopefully be improved later.

After power up, the display should flash and the menu screen should appear. Select either slide show or ebook mode using the up/down main buttons. The same image set is used for both modes, but the transition between images will differ depending on the mode.

Title Screen

Ebook Mode
Push the down button to move forward and the up button to move back. If you are at the beginning of the image set and you press the back button, the same image will appear. If you are at the end of the image set and press the forward button, the same image will appear. Otherwise, pressing one of these buttons will show either the previous or next image in the set, according to the button. Press the small button with the light gray center to return to the menu screen. Button input is ignored until the image update is complete, which takes 1-2 seconds.

There is also a delay between button depression and when the display starts to change when moving forward and back in the image set. This is due to the time it takes the computer to copy the image from the MMC card to RAM and decompress it, and can vary from essentially zero to a few seconds, depending on the complexity of the image (and thus its compressed size).

The file ebook.sh on the MMC card is used by the processor to control operation in ebook mode. This file can be edited or replaced to change behavior in ebook mode.

Slideshow Mode
In slideshow mode, all the images in the set are shown sequentially in an infinite loop. The delay between images is about 10 seconds by default.

Holding down the small button with the light gray center through an image update will return you to the main menu screen.

The file slides.sh on the MMC card is used by the processor to control operation in slideshow mode. This file can be edited or replaced to change behavior in slideshow mode, for example to change the delay between image updates.

Installing new batteries (alkaline model):
Use 3 AAA batteries. Always make sure to insert all three batteries into the tube with the positive bump going in first. Batteries should last around 3 hours in slideshow mode with 10 seconds between image changes. Smaller delays between images, in either mode, will reduce battery life. Longer delays will increase battery life. Use very high quality alkaline batteries, for example Panasonic Industrial batteries (Digikey part number P146-ND).

Charging batteries (Li-model):
Plug the 12V power adapter into the H2 (and into a wall socket). Batteries should charge in about 3 hours.

Battery life is currently shorter than it should be because good power management software has not been written. Kernel and bootloader modifications are required for putting the Xscale into ultra low power mode between updates. These projects have not been a top priority to date. So when the book is just sitting there, the screen is not using any power at all, but the Xscale is chewing up 100-200 mA.

Adding new images to the image set
The system uses the images stored on the mmc card in the directory called images_bz. The images are PPM raw 8 bit grayscale, 800x600 (landscape), compressed using the bzip2 algorithm. The order the images are shown is determined by their order in a listing of the images_bz directory, so for instance a.ppm.bz2 would be shown before b.ppm.bz2. Images can be removed from the set by deleting them from this directory, or moving them to another directory. Images can be added to the set by copying them into this directory.

Design partially original and partially ripped off from other websites
by Holly Gates