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Wearwulf

Schematics

The experimental version of the Wearwulf's schematic (»file:wearwulf-schematic-20040303.pdf) is now available.

This schematic has not been checked in detail, and should be used for information purposes only. Component values are subject to rationalisation, and change.

»file:wearwulf-schematic-20040303.pdf
Note: Subject to change.

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Why is HLTOL generated inside the CoolRunner?

When the power to the display is removed HLTOL must be brought low to prevent the display being damaged. (HLTOL determines whether the display should be mirrored - dependent upon your optics.)

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Why do you create a 1.8V reference voltage when you already have a 1.8V supply?

The 1.8V reference voltage is generated from the 2.0V supply, which can be switched off. This means that the refence voltage is switched off with that supply, preventing damage to the display.

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What happens when the batteries are removed?

The Mega-8L microcontroller will detect the drop in voltage, and inform the Wearwulf to go into low power mode. The capacitances at the power supplies' outputs may be sufficient to prevent data loss while the batteries are replaced, provided the low power mode can be entered quickly enough. (The value of capacitor will probably need changing.)

This version of Wearwulf is experimental - a different mechanism may be required.

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Have you forgotten anything?

Yes, I'm sure I have :-) I thought it best to get this provisional version out there, and get on with laying out the PCB. The design will need refining anyway, and I need to make sure that the central premise works first.

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