AVR-Chat

Hi all,

I have a project that would need either 6 ADC inputs of 12 bit, or 
use 6 comparitors.

I preferr comparitors for their speed and digital value.

Is there a uC that would offer 6 internal comparitors ?

Dave

--- In AVR-Chat@yahoogroups.com, "Dave Mucha" <dave_mucha@y...> wrote:

> Is there a uC that would offer
> 6 internal comparitors ?

Assuming comparators will do the job, you could take a look at the 
Cypress PSoC. The Cypress Web site is seriously broken right now, 
though, so don't waste too much time. You may have to go straight to 
their Customer Support and ask the question directly.

Graham.

Hi,
Atmel AVR microcontrollers can link the adc mux output
to one of the internal comparator input pins. So by
quickly switching the adc channel you can apply
different signals to the comparator. May be you can
facilitate this feature in your circuit.

Hope this helps

Murat Karadeniz
http://www7.brinkster.com/mukas/


--- Dave Mucha <dave_mucha@yahoo.com> wrote:

> Hi all,
> 
> I have a project that would need either 6 ADC inputs
> of 12 bit, or 
> use 6 comparitors.
> 
> I preferr comparitors for their speed and digital
> value.
> 
> Is there a uC that would offer 6 internal
> comparitors ?
> 
> Dave
>  
> 
> 



		
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I am trying to program a mega8 chip (actually I have tried 3 different
ones) and I keep getting errors entering programing mode.  I am using
the STK500 board and AVR Studio version 4.09.  The chips are the flat
quad package and I think that is where my problem is arising since I
must use program off of the stk500 board (which I have never done
before).  I made a quick pcb
(http://www.dpicts.com/ForumPics/mega8a-2.jpg) to attach to the 6 pin
connector on the stk500 to program the chip.  I am not changing any
jumpers or anything on the stk500 (maybe this is my problem).  I have
made 4 different PCBs thinking that I had a trace wrong or broken, but
all pcbs and all three chips have failed.  Anyone have any suggestions
as to what I might be doing wrong?
Thanks,
Daniel

At 04:23 PM 9/29/2004, Daniel Boyer wrote:

>I am trying to program a mega8 chip (actually I have tried 3 different
>ones) and I keep getting errors entering programing mode.  I am using
>the STK500 board and AVR Studio version 4.09.  The chips are the flat
>quad package and I think that is where my problem is arising since I
>must use program off of the stk500 board (which I have never done
>before).  I made a quick pcb
>(http://www.dpicts.com/ForumPics/mega8a-2.jpg) to attach to the 6 pin
>connector on the stk500 to program the chip.  I am not changing any
>jumpers or anything on the stk500 (maybe this is my problem).  I have
>made 4 different PCBs thinking that I had a trace wrong or broken, but
>all pcbs and all three chips have failed.  Anyone have any suggestions
>as to what I might be doing wrong?

First, check that you're connecting the data to the DI and DO pins, NOT MOSI and MISO.
Second, check the clock rate on the programmer, slow it down a bit. If the part is running on the internal 1MHz osc, the STK500 or AVRISP can outrun it at the faster speeds.

At 04:29 PM 29/09/04 -0500, you wrote:
>
>First, check that you're connecting the data to the DI and DO pins, 
>NOT MOSI and MISO.

??? For the Mega8? :-)) It is still Mosi and Miso.


Regards

John Samperi

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  11 Brokenwood Place Baulkham Hills, NSW 2153 AUSTRALIA
         Tel. (02) 9674-6495       Fax (02) 9674-8745
               Email: samperi@ampertronics.com.au
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* Electronic Design   * Custom Products   * Contract Assembly
******************************************************

At 05:36 PM 9/29/2004, John Samperi wrote:

>At 04:29 PM 29/09/04 -0500, you wrote:
>>
>>First, check that you're connecting the data to the DI and DO pins, 
>>NOT MOSI and MISO.
>
>??? For the Mega8? :-)) It is still Mosi and Miso.

Duh.. :) 8 not 128.. 

Anyway, the rest holds.

How about a pullup on the reset pin? (Does the programmer use an open drain driver on reset?)
I didn't see any other parts on the pcb layout. 

Bruce

Dave VanHorn wrote:

> 
> At 05:36 PM 9/29/2004, John Samperi wrote:
> 
> >At 04:29 PM 29/09/04 -0500, you wrote:
> >>
> >>First, check that you're connecting the data to the DI and DO pins,
> >>NOT MOSI and MISO.
> >
> >??? For the Mega8? :-)) It is still Mosi and Miso.
> 
> Duh.. :) 8 not 128..
> 
> Anyway, the rest holds.

>
>(http://www.dpicts.com/ForumPics/mega8a-2.jpg) to attach to the 6 pin
>connector on the stk500 to program the chip.  I am not changing any
>jumpers or anything on the stk500 (maybe this is my problem).  I have
>made 4 different PCBs thinking that I had a trace wrong or broken, but
>all pcbs and all three chips have failed.  Anyone have any suggestions
>as to what I might be doing wrong?



The target is powered from somewhere, right?

What do you get when you try to read the signature?

Pin-18 (AVCC) is floating; it needs to be connected to the supply. And at least one .1 mfd 
cap between the supply and ground for bypass.

Bruce

Dave VanHorn wrote:

> 
> >
> >(http://www.dpicts.com/ForumPics/mega8a-2.jpg) to attach to the 6 pin
> >connector on the stk500 to program the chip.  I am not changing any
> >jumpers or anything on the stk500 (maybe this is my problem).  I have
> >made 4 different PCBs thinking that I had a trace wrong or broken, but
> >all pcbs and all three chips have failed.  Anyone have any suggestions
> >as to what I might be doing wrong?
> 
> The target is powered from somewhere, right?
> 
> What do you get when you try to read the signature?

> 
> The target is powered from somewhere, right?
> 
> What do you get when you try to read the signature?
> 

I thought that they STK500 provided power (as long as the Vtarget Jumper
was on, which it is) via the Vtg pin and Gnd pin of the six pin
header... If this is not correct then this is probably my problem.  If I
try to read the signature I get an error (Entering programing mode:
error).  I have turned the clock speed of the STK500 to every different
option with no luck...   Also about the pull up on reset, I thought that
the STK500 did all of that via the rst pin on the 6 pin connector, was I
wrong?  I did build a PCB that is basicly identical to this one only it
is for a tiny15 in 8pin soic package; I managed to program two tiny15's
successfully, so that's why I made the above assumptions (I can upload
that pcb image if that matters).

Thanks,
Daniel

> Pin-18 (AVCC) is floating; it needs to be connected to the 
> supply. And at least one .1 mfd 
> cap between the supply and ground for bypass.

Didn't reallized that AVCC had to be connected if I wasn't using the
Analog circuty...maybe this is my problem...Thats a quick and easy fix
that I'll try right now.

Daniel

Ok, I broke down and checked the STK500 schematic. The six pin ISP header, J906, is
connected as follows:

	1 - MISOT  (O.C. output with 1K pullup)
	2 - VTG    (hardwired, no jumper)
	3 - SCKT   (O.C. output with 1K pullup)
	4 - MOSIT  (emitter of common-base Q901B with 47K pullup)
	5 - /PROGRST
	6 - GND

So power is no problem, it's whatever you have the board set to.

Then I tracked down what was driving /PROGRST. It has the collector of Q203B pulling it down
along with a 22K resistor R208 to GND. The only pullup is Q201A and it's is only active when
doing high voltage parallel programming; it pulls the line up to +12v. So it looks like a 4.7K
or so pullup is needed on the reset line.

Bruce


Daniel Boyer wrote:

> 
> 
> > Pin-18 (AVCC) is floating; it needs to be connected to the
> > supply. And at least one .1 mfd
> > cap between the supply and ground for bypass.
> 
> Didn't reallized that AVCC had to be connected if I wasn't using the
> Analog circuty...maybe this is my problem...Thats a quick and easy fix
> that I'll try right now.
> 
> Daniel

>Is necessary to make one connection between the PC2 to BSEL2 (only for
ATmega8) in the STK500 board.
>
>Edson

I thought that was only for high voltage programing, not ISP?

Daniel

Okay, I have tried all the suggestions and even made a SMT to DIP
converter so that I could plug the chip into the STK500 socket and
nothing is working... I don't know what could be going wrong... I really
need to get this cicuit finish (and everything is finished except for
programing the chip) so I guess I am just going to go back to DIP Chips
and call it a loss on the smd guys (just hated to have a board with all
smd componets and then a big through hole dip chip siting in the middle
of it all taking up so much space).
Thanks for all your help,
Daniel

At 10:22 AM 9/30/2004, Daniel Boyer wrote:



>Okay, I have tried all the suggestions and even made a SMT to DIP
>converter so that I could plug the chip into the STK500 socket and
>nothing is working... 

Is it possible that this chip was programmed with some hosed fuse settings?
I've also had trouble, back on the 8515, when my code initted the SPI port very quickly after reset, this interfered with the programming.

Well, I have now tried everything... Including trying to use parallel
high voltage programing, all to no avail... When I use the high voltage
mode, I can at least enter programing mode, but I can't program (and
reading the signature results in 0xff 0xff 0xff 0xff  which is of course
wrong).  I was starting to think that my STK500 might have gone bad, so
I stuck a mega8 dip packaged chip in and it programed perfectly.  I even
pulled my last new (untouch from digikey) smd packaged mega8 out today
and tried it on a new smd to dip adaptor board (that I made last night
that maps ALL pins) and it gives the same results.  At this point I am
just going to have to call the 5 smd mega8 chips a loss for now and
redesign my pcb for the dip package (and order more mega8's as all my
dip packaged ones are ATMEGA8-16PC and my smds were ATMEGA8L-8AC so that
I could use them with a single lithium cell).  Thanks for everyone's
help,
Daniel