Post by thread:[EE] [AVR] AVR part availabilities and A2D convert

A colleage is considering the AVR for a product line. He's concerned about the availability of the parts firstly. Second issue is the A2D converter built in reference. The spec seems a bit odd. +- 0.1 V from nominal from a 1.1 V reference is around +-10% seems rather strange for that to be called a voltage reference too me. Can anyone shed light onto weather this is indeed how bad the reference is? Is it really that pointless to use the internal reference or not? __________________________________ Do you Yahoo!? Yahoo! Mail - Easier than ever with enhanced search. Learn more. http://info.mail.yahoo.com/mail_250

At 07:10 AM 20/05/2005, you wrote: >He's concerned about the availability of the parts firstly. Which AVR? >Second issue is the A2D converter built in reference. ......... >Is it really that pointless to use the internal reference or not? There seem to be some 'ISSUES' with the built in reference, I haven't had to use the A/D converter for precision measurements yet so can't really comment. But you can always use VCC as Vref (internally switched) of use an external Vref. Regards John Samperi ****************************************************** Ampertronics Pty. Ltd. 11 Brokenwood Place Baulkham Hills, NSW 2153 AUSTRALIA Tel. (02) 9674-6495 Fax (02) 9674-8745 Email: spam_OUTsamperiTakeThisOuTampertronics.com.au Website http://www.ampertronics.com.au * Electronic Design * Custom Products * Contract Assembly ******************************************************

In my opinion PIC is more available than AVR. For example Avnet has no PDIPs available other than the 8515. All American is recommended by an Atmel FAE. Regards, Chetan On 5/19/05, John Samperi <.....samperiKILLspam@spam@ampertronics.com.au> wrote: {Quote hidden}> At 07:10 AM 20/05/2005, you wrote: > >He's concerned about the availability of the parts firstly. > > Which AVR? > > >Second issue is the A2D converter built in reference. > ......... > >Is it really that pointless to use the internal reference or not? > > There seem to be some 'ISSUES' with the built in reference, > I haven't had to use the A/D converter for precision measurements > yet so can't really comment. But you can always use VCC as Vref > (internally switched) of use an external Vref. > > Regards > > John Samperi > > ****************************************************** > Ampertronics Pty. Ltd. > 11 Brokenwood Place Baulkham Hills, NSW 2153 AUSTRALIA > Tel. (02) 9674-6495 Fax (02) 9674-8745 > Email: samperiKILLspamampertronics.com.au > Website http://www.ampertronics.com.au > * Electronic Design * Custom Products * Contract Assembly > ****************************************************** > > > -

At 02:10 PM 20/05/2005, you wrote: >In my opinion PIC is more available than AVR. I guess it depends on where you are AND which part you may want to use and how many you need. I have no problems getting AVR in Australia from several distributors. I have just delivered some equipment that uses an ATMEGA8535 and an ATMEGA8 both in PDIPs. Regards John Samperi ****************************************************** Ampertronics Pty. Ltd. 11 Brokenwood Place Baulkham Hills, NSW 2153 AUSTRALIA Tel. (02) 9674-6495 Fax (02) 9674-8745 Email: .....samperiKILLspam.....ampertronics.com.au Website http://www.ampertronics.com.au * Electronic Design * Custom Products * Contract Assembly ******************************************************

>A colleage is considering the AVR for a product line. > He's concerned about the availability of the parts firstly. Look at http://www.findchips.com . It gives some guide as to what you can expect. Anything can dry up on you suddenly. The volumes and time span of the project influence this of course. {Quote hidden}> Second issue is the A2D converter built in reference. The spec > seems a > bit odd. +- 0.1 V from nominal from a 1.1 V reference is around > +-10% > seems rather strange for that to be called a voltage reference too > me. > Can anyone shed light onto weather this is indeed how bad the > reference > is? Is it really that pointless to use the internal reference or > not? Stability of a band gap reference over all relevant variables is more important than absolute initial accuracy. In many cases a reference can be expected to be more stable than absolutely accurate. This is easily accomodated with digital processing of the result. A key feature of a band gap reference is it's relative temeperature stability (achieved by summing two voltages which counter track with temperature). Odds are that you can calibrate the ADC to far better than 10% with a single reading during setup. I just checked the ATMega48 datasheet. Reference is 1.1V +/- 0.1V and there is no spec on stability. Some testing needed to see what can actually be expected BUT it will be far better than 10%. RM

At 11:10 PM 5/19/2005, Chetan Bhargava wrote: >In my opinion PIC is more available than AVR. For example Avnet has no >PDIPs available other than the 8515. All American is recommended by an >Atmel FAE. The 8515 is obsolete, isn't it? The 8535 or the mega-8 might be a better choice.

----- Original Message ----- From: "Dave VanHorn" <EraseMEdvanhornspam_OUTTakeThisOuTdvanhorn.org> To: "Microcontroller discussion list - Public." <piclistspam_OUTmit.edu>; "Microcontroller discussion list - Public." <@spam@piclistKILLspammit.edu> Sent: Friday, May 20, 2005 3:35 PM Subject: Re: [EE] [AVR] AVR part availabilities and A2D convertor > At 11:10 PM 5/19/2005, Chetan Bhargava wrote: > >In my opinion PIC is more available than AVR. For example Avnet has no > >PDIPs available other than the 8515. All American is recommended by an > >Atmel FAE. > > The 8515 is obsolete, isn't it? The 8535 or the mega-8 might be a > better choice. The AT90S is obsolete, but the newer ATmega8515 isn't. As per a previous topic, All American would probably expect a large quantaty order. There are other disti's around who will have them in stock, depends on where you are in the world, google is your friends :) (A)vailable (V)ery (R)arely A little joke posted around the time when Atmel had some much larger lead times than they have these days. Bryan -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.322 / Virus Database: 266.11.12 - Release Date: 17/05/2005