AVR-Chat

Many thanks Cobb, My project is more along the the line of signals so
a large number of i/o and adc ports isn't on the top of my list. It is
too bad that Atmel didn't open more of the ports up for the robotics
engineer. The butterfly would indeed be a great platform to start from
if the ports weren't so tied up. But none the less $20 can't be beat.

Thanks again!


--- In AVR-Chat@yahoogroups.com, "Cobb, Quentin" <quentin_cobb@t...>
wrote:
> This an email that Craig Limber sent to our robotics list,
commenting on the
> suitability of the Butterfly as a robot controller:
> 
> Hi there;
> 
> I've been doing some analysis of the AVR Butterfly to see what
> usefulness it might be as a robotics controller and thought I would
> share the results with everyone.  Everything I found I got from the
> schematics in the butterfy's userguide I downloaded from Atmel.
> 
> The big thing I was looking for was useful I/O pins, especially
> I/O pins with analog to digital converters or pulse width modulation
> channels.   
> 
> Two 8-bit ports (with associated I/O pins) have connectors that we
> can get at: port B and port D.  Unfortunately, those ports are
> shared with lots of other stuff.
> 
> All four PWM channels are either shared with the navigation switch or
> the piezo speaker.  We are stuck with the speaker unless we disconnect
> it.  If we want to use the remaining PWM channels we just have to make
> sure that no stupid humans fiddles with the button at the same time.
> 
> The rest of port B is shared with the ISP port (which isn't a big
> deal as long as we use those pins for input only), the navigation
> switch or the dataflash.
>  
> Port D also has a connecter but those pins are shared with the LCD.
> According to the schematic they are connected but I am not sure
> if the LCD actually uses them.  I will probably hook soemthing up
> to see if signals are being sent when the LCD gets used.  If they
> are used by the LCD then that entire port will be unuseable unless
> the LCD is turned off.
> 
> However, all is not lost.  There are 4 pins on the JTAG port that
> are useful (PF4-7).  They are also ADC channels.  That's cool.
>  
> The USI interface is also open for us (pe4-6).  The other ports
> such as the USART have some circuitry in between making it less
> likely we can use them for anything else.  
>  
> So, basically, we aren't left with many ports for other stuff.  
> However, it's still a bargain for the cost and what you get.
> 
> I have a little table that shows the pin pin mappings.  
> 
> http://members.shaw.ca/climber/avrbutterfly
> 
> climber
> 
> -----Original Message-----
> From: chrltn101 [mailto:chrltn101@y...] 
> Sent: March 9, 2004 1:18 PM
> To: AVR-Chat@yahoogroups.com
> Subject: [AVR-Chat] Butterfly
> 
> 
> Hi all,
> 
> I was thinking about buying a butterfly, but before doing so I wanted to
> ask around and see what kind of reputation the board has (ie. does it
> actually do what the data sheets say it supposed to do, what kind of
> hinderances you ran into)
> 
> All comments/recommendations greatly appreciated,
> 
> -John
> 
> 
> 
>  
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