[Gghc-discuss] More stuff on hardware design

[Erich Heine]

Hi all,

So this is awesome! Lots of great input from Jonathan here. It suddenly
feels like we have something do-able rather than just an idea... IME a major
step in engineering a project.

At this point tho, I am a bit confused, so I decided to turn on the wiki for
our redmin instance, and have tried to start mapping this project out there.
I have started to try and suss out a parts list and some high level stuff
from these last few emails.

I'd suggest we work from there, rather than email around, as that will help
keep the confusion to a minimum (no tracking are we still doing $X or did it
get cancelled by email $Y?). The wiki can be considered the most current
actual plan.

Lets keep the rockstar stuff going, and we can end up with an amazing
project!

Regards,
Erich

PS it is past my bedtime, so any misspellings, grammatical faux pas and
email induced rudenesses are strictly a result of diminished wordsmithing
capabilities, and are not intended to be taken as my actual opinion or
stance.

On Sun, Apr 17, 2011 at 9:02 PM, Jonathan Manton <jmanton at illinois.edu>wrote:

> It turns out we can't use I2C from the user's arduino to our electronics.
>  The I2C libraries take two of the analog I/O pins (I2C is implemented in
> hardware).  So if we use I2C, we lose 2 analog peripherals (probably the
> joystick).
>
> Instead, I suggest we use the NewSoftSerial arduino library to connect the
> two arduinos (the user's one and the one we use to control the board).  The
> problem with this is we still have to talk to the LED controller somehow.
>  My suggested solution is that we lose two of the buttons up by the LCD.
>  Then the pin allocation on the target arduino will be (out of 32 I/O pins
> available):
>
> 2 for serial connection to talk to user arduino
> 2 for I2C to talk to LED controllers
> 13 to talk to graphics LCD
> 3 to talk to buttons next to graphics LCD
> 6 to control analog switch
> 12 to "switch" digital I/Os (6 LEDs, 4 buttons, joystick button, missile
> switch)
>
> Uh oh, that's 38 I/Os.  Hm.  We would only have 30.
>
>
> So, new plan, which actually simplifies things anyway.
>
> We use a regular stock arduino for the control of the board.  It has 20
> I/Os available.
>
> 2 for serial connection to talk to user arduino
> 2 for I2C to talk to LED controllers and I/O expander (see below)
> 13 to talk to graphics LCD
>
> Then we use an I2C I/O port expander to control the 6 analog switch ports
> and to "switch" the digital I/Os.  We can use the 3 remaining pins to either
> control the buttons next to the graphics LCD (if we want 3), or use extra
> ports on the I/O expanders to control those buttons.
>
> There are like tons of I2C I/O expanders.  But there is a tutorial on how
> to use the PCA9535 (or PCA9555) with an arduino (at
> http://www.neufeld.newton.ks.us/electronics/?p=241).  Those are 16-bit
> expanders.  So 2 of them will do.
>
> So on the I/O expanders will be:
> 6 for analog switch
> 12 for switching user peripherals (6 LEDs, 4 buttons, joystick button,
> missile switch)
> _______________________________________________
> Gghc-discuss mailing list
> Gghc-discuss at lists.chambana.net
> http://lists.chambana.net/mailman/listinfo/gghc-discuss
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.chambana.net/pipermail/gghc-discuss/attachments/20110418/ee9c9210/attachment-0001.html>