AVR-Chat

Yes, you can do it in the Tiny11.

	Mark Jordan

On 18 Nov 2004 at 15:53, Tony Vandiver wrote:

> 
> Can you use Reset for GPIO?  Possible in the ATTiny15, don't know about the
> 11.
> 
> ----- Original Message -----
> From: "Jose Fuentes" <josecarlosfuentes@yahoo.com.ar>
> To: <AVR-Chat@yahoogroups.com>
> Sent: Thursday, November 18, 2004 2:56 PM
> Subject: Re: [AVR-Chat] SERIAL PORT IN ATTINY
> 
> 
> >
> > Thanks to everybody for the help!  I didn't realize
> > that using a XTAL I have only one pin left.  Not sure
> > but maybe would be better to use I2C to communicate
> > because it doesn't require a XTAL.
> >
> > Regards,
> > Jose
> >
> >
> > > 8 pin chip, VCC, Gnd, X1, X2, TXD, RXD, Reset..  One
> > > pin left.
> >
> >
> >
> >  --- Dave VanHorn <dvanhorn@dvanhorn.org> escribió:
> > >
> > > At 08:49 AM 11/18/2004, Jose Fuentes wrote:
> > >
> > >
> > > >I want to use a Attiny11 (price under 0.54) and
> > > >implement a serial port.  Since it doesn't have a
> > > >USART I have to write the software to allow the
> > > >microcontroller to send and receive data.  If
> > > somebody
> > > >has done something like this in assembly or C
> > > please
> > > >let me know.  Attiny11 only has 1KB FLASH and 32
> > > >general purpose registers.
> > > >Thanks.
> > >
> > > You may be a bit hosed here.
> > > The T11's RC osc isn't calibrated, so you'd have to
> > > use a resonator or xtal
> > > at the cost of two pins.   If that works for you,
> > > then set up an int at the
> > > baud rate.
> > >
> > > Receive:
> > > Put RXD on the hardware int pin (PB1)
> > > When you see the start bit, set the timer to int you
> > > in half a bit time.
> > > When that int fires, sample the data. If still low,
> > > you have a valid start
> > > bit, and the next 8 timer ints simply sample and
> > > shift.
> > > If you want, you can pay attention to the stop bit,
> > > one more int, should be
> > > "idle".
> > >
> > > Transmit:
> > > TXD on any pin.
> > > Set the int to fire at the baud rate.
> > > Send a start bit, 8 data, and one stop..
> > >
> > >
> > > It's not that awful, but that means you have only
> > > two more pins available
> > > on the chip, and one of them is reset..
> > >
> > > 8 pin chip, VCC, Gnd, X1, X2, TXD, RXD, Reset..  One
> > > pin left.
> > >
> > > Don't spend it all in one place!
> > >
> > >
> > >
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