Uzebox AVCore "Gamer" Baseboard

Topics regarding the Uzebox hardware/AVCore/BaseBoard (i.e: PCB, resistors, connectors, part list, schematics, hardware issues, etc.) should go here.
havok1919
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Re: Uzebox AVCore "Gamer" Baseboard

Post by havok1919 » Sat Dec 27, 2008 3:47 am

DavidEtherton wrote:Clay, what's the power button actually supposed to do? I could have sworn it actually cycled power on the SparkFun demo that shipped with it (which I've long since flashed over). For that matter, I thought the LED's were under user control as well.

I know it can be read from software (and I emulate it now for maze demo happiness).
The "power" button is just connected to a port IO pin-- PORTD.3 and the LED connects to PORTD.4

Power (and LED) control is thus 'cooperative' with the MCU. On the earlier baseboards I had a circuit that toggled power to the module in hardware, but after some discussion I decided it would be useful to have one "always available" input. (That way if we wanted to have things like "press and hold X seconds to force the bootloader to start" or "press and hold when you apply power to do Y" we'd have it available and without any knowledge of what/if controllers were attached, etc.) The LED was also going to be hard-wired to power, but it was super useful for ("real") hardware timing experiments and as a trigger for external debug hardware (logic analyzer, scope, etc.) and I'm a sucker for little pulsing "powered, but sleeping" type indicators. ;-)

If you want to emulate them-- check the DDRD (Data Direction Register, PORT D) for if they're configured as an input or output (input in the case of PORTD.3, output in the case of PORTD.4). The PORTD output register for bit 3 will be set to '1' for the power switch (to enable the internal pullup resistor). PORTD.4 is a current sink, so the LED will light when the bit is '0' and turn off when the bit it '1'.

The "ESD Attack" hex file drives the LED and reads the power switch for testing. I didn't want to go mucking about in the kernel to get true low-power sleep mode going, so instead when the power switch is toggled I just disable the NTSC encoder clock output to turn off the video. ;-)

(Sorry for the slow reply-- off visiting my folks for Christmas!)

-Clay

DavidEtherton
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Re: Uzebox AVCore "Gamer" Baseboard

Post by DavidEtherton » Fri Jan 09, 2009 12:45 am

My AVCore+Baseboard has been "on" since mid-December when I first got it, mostly because I'm worried that if I keep pulling the power adapter out enough times it's eventually going to break something.

Is this a problem? My PC is usually asleep,, but the AVR ISP mkII is plugged into it and the baseboard.

-Dave

havok1919
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Joined: Thu Aug 28, 2008 9:44 pm
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Re: Uzebox AVCore "Gamer" Baseboard

Post by havok1919 » Fri Jan 09, 2009 12:57 am

DavidEtherton wrote:My AVCore+Baseboard has been "on" since mid-December when I first got it, mostly because I'm worried that if I keep pulling the power adapter out enough times it's eventually going to break something.

Is this a problem? My PC is usually asleep,, but the AVR ISP mkII is plugged into it and the baseboard.
Shouldn't be a problem! The power adapters I shipped can fit pretty tight, so I usually just leave 'em plugged in too. The parts should run continuously for ages without any issues. Once nice thing about (many) MCU's is that they tend to be 'industrial' in nature and as such have larger transistors and protection diodes on the IO pads and they aren't using the latest super-small geometries to fail. The transistor counts are also pretty laughable compared to a RAM or modern CPU, so the MTBF's are really high by comparison usually.

-Clay

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