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1  Forum 2005-2010 (read only) / Troubleshooting / Re: Loading bootloader on ATMega2560 on: July 10, 2010, 10:31:35 pm
The genuine  AVRISP mkII programmer fixed the problem and the prototype works fine now.
2  Forum 2005-2010 (read only) / Troubleshooting / Loading bootloader on ATMega2560 on: July 05, 2010, 09:41:03 pm
I'm working on a prototype of a board using a ATMEGA2580 and
trying to use these instructions and code to load the bootloader:

I use the Arduino "Burn Bootloader" and after a couple of minutes I
get the error that others have reported using USBTinyISP on the
Arduino Mega:

avrdude: verification error, first mismatch at byte 0x3e000
                               0x0d != 0xff
avrdude: verification error; content mismatch

I assume the the bootloader is getting loaded, but when I plug into
the onboard USB I do not get a port setup in Windows. I'm guessing
the problem is in the RT232RL circuits. I used the same layout for
a previous prototype with an ATMega1280 and it worked fine.

The PB7 (D13) led is flashing about every 5 seconds so the
CPU seems to be alive. Can anyone confirm that if only
the bootloader is loaded that the D13 LED flashes?

I'm using a USBTinyISP clone but I've ordered a genuine AVR
programmer to try and I'm going to review the USB circuits and check
for shorts, etc. If all that fails I may pull the 2560 and replace it
with a 1280.
3  Forum 2005-2010 (read only) / Interfacing / Re: Level shift 0v-1v signal to attachInterrupt on: March 05, 2010, 02:31:30 pm
Thank for all the input guys. I tested it last night and it worked great
both with R2 and using the internal pull up.

4  Forum 2005-2010 (read only) / Interfacing / Re: Level shift 0v-1v signal to attachInterrupt on: March 04, 2010, 05:01:12 pm
Great. I'll give those a test and see how it works. Thanks much!

Seems like the inversion won't be an issue as all I care about is
reading a change from high to low (or vice-versa) using
attachInterrupt or am I not understanding something?
5  Forum 2005-2010 (read only) / Interfacing / Re: Level shift 0v-1v signal to attachInterrupt on: March 04, 2010, 02:16:31 pm
How wrong can a guess be?

Totally? Thanks for helping a total newbie.  smiley

There are no markings at all on the hall effect sensor.

I did some research and found what you described is as a
Common Emitter Amplifier circuit. I'm having trouble understanding
the math to size the resistors R1 and R2. Am I on the right
track with the circuit below? Can anyone help with the math or
sizing the resistors?

Here is a link to the page describing the Common Emitter Amplifier circuit.

And this one:

And one more:
6  Forum 2005-2010 (read only) / Interfacing / Re: Level shift 0v-1v signal to attachInterrupt on: March 02, 2010, 04:31:38 pm
Thanks for the replies!

No it's true digital output from a hall effect sensor, either 0 or 1v. On
the scope it looks like a square wave. Not terribly fast but I need
digital accuracy.

The BC238 looks good but there is not a sample circuit in the datasheet.

I'm guessing the collector would be my 1v signal, base to ground
and the emitter would be my 5v out? Would I need any caps to filter
he output or anything else special in the way of a circuit?

7  Forum 2005-2010 (read only) / Interfacing / Level shift 0v-1v signal to attachInterrupt on: March 02, 2010, 01:05:34 pm
I'm looking for a transistor or IC that will shift a voltage range of 0 to 1 volts to 0 to 5 volts for use on a digital interrupt pin using attachInterrupt.

Anyone done this before?

8  Forum 2005-2010 (read only) / Development / Re: Anyone done any small scale production runs? on: December 12, 2010, 05:07:37 pm
Do you intend to sell them? (I assume you do)

How much spare time do you have?

Could you earn more money by doing something else?

Yes, I do plan to sell them and your point about time is well taken. I
think the biggest reason other than cost that i'd like to do these
myself is the control over the product and the fact that i can change
the design every 10 boards and don't have to worry about the 90
sitting on the shelf if I had someone else assemble a batch.

jabber: i also have hands that get painful after a while and these are
all SMC 0604 and even some 0402 components. I guess i should
have mentioned that as well, the smaller sizes do slow you down a bit.

9  Forum 2005-2010 (read only) / Development / Anyone done any small scale production runs? on: December 12, 2010, 04:06:43 pm
I'm trying to decide if it would be worth it to farm out the assembly of
small production runs of 20 or so boards (150 components) or build
them myself. This will never be a 1000 unit or even a 100 unit deal.
At most I think 10 units per month is what I will be assembling.

I've assembled a lot of prototypes and I'm decently quick but have
never just done a grind of 10 boards, I assume it's much less enjoyable.

If you've done this, would you do it again?

What types of problems did you run into?

Did you find it less expensive in the long run just to pay an outside company to do the assembly?
10  Forum 2005-2010 (read only) / Development / Re: Mega2560 bootloader source on: July 10, 2010, 10:35:37 pm
Thanks for posting this!

I can verify it works with a prototype board with a 2560. smiley
11  Forum 2005-2010 (read only) / Development / Merging multiple gerbers for multi-panel project on: July 07, 2010, 12:59:25 pm
I'm about to order multiple designs in one batch and I needed to
merge the gerbers into one single gerber. I did some searching
and found that others have used a free program called GerbMerge:

I saw a lot of posts that said it was hard to use and several people
had given up. Once I had GerbMerge installed I had my merged
Gerbers ready to go in about 15 minutes. I thought I'd document the
steps to help anyone that needs to use it. I'm using it on linux (FC10) but
I assume windows would be similar.

-- Install GerbMerge and it's prerequisites.
-- Copy your gerbers to a folder, I named them pcb1 and pcb2.
-- Setup a config file, I used panel.cfg, I'll copy it in below.
-- run GerbView: gerbview panel.cfg

The sample config file has a lot of comments that describe each
option. I removed them to make it easier to read. I'm using GP
and their panel size is 14.5 x 10. Be sure to edit this in the config
file and also the number of boards you want. You also need a
board outline layer .bor that I have not supplied separately in the
past, it's been on the top silk later.

I used the automatic placement option in GerbView and it seemed to
be as good as I could have done manually.

Here is the panel.cfg file:


projdir = .

MergeOut = merge1


#ExcellonDecimals = 4
CutLineLayers = *topsilkscreen,*bottomsilkscreen
CropMarkLayers = *topsilkscreen,*bottomsilkscreen
FabricationDrawingFile = %(mergeout)s.fab
#FabricationDrawingText = %(projdir)s/fabdwg.txt
ExcellonLeadingZeros = 0
OutlineLayerFile = %(mergeout)s.oln
ScoringFile = %(mergeout)s.sco

# panel size here:

PanelWidth = 14.5
PanelHeight = 10

LeftMargin   = 0.1
RightMargin  = 0.1
TopMargin    = 0.1
BottomMargin = 0.1

XSpacing = 0.125
YSpacing = 0.125

CutLineWidth = 0.01

CropMarkWidth = 0.01

AllowMissingLayers = 0

DrillClusterTolerance = 0.002

MinimumFeatureSize = *topsilkscreen,0.008,*bottomsilkscreen,0.008

Prefix = %(mergeout)s

ToolList = toollist.%(prefix)s.drl
Placement = placement.%(prefix)s.txt

# options below here are for each PCB in your design

# this is for PCB 1




Repeat = 3

# this is for PCB 2




Repeat = 3

12  Forum 2005-2010 (read only) / Development / Hotair re-work station, what temps, any tips? on: June 07, 2010, 05:15:41 pm
I bought a new re-flow station off ebay last week and jumped in and
started trying it out. I just realize the temp LED is marked in Celsius
not Fahrenheit. smiley-sad  smiley-sad (Yea... I know big mistake). I was thinking
it was 375F and I've had some problems with chips that I think
are heat related.

At 375C it works quickly, less than 30 seconds to re-flow.

What kind of air temps does everyone use?
How about nozzle size and airflow?
How long should it takes to re-flow?

Any tips so I don't fry anything else? smiley
13  Forum 2005-2010 (read only) / Development / Re: Looking for Eagle file for mega pinout on: March 24, 2010, 06:03:25 pm
I've got one too.

Not sure where it came from but PM if you still need it.
14  Forum 2005-2010 (read only) / Development / Re: New design: MegaSquare using ATMEGA2560 on: March 24, 2010, 06:06:33 pm
I have the core files working for the 2560 for version 018 of the Arduino IDE. There is still some more work to be done and the pin definition tables will have to be created for your particular pin out. I will be glad to help you with this when you are ready.


Thanks Mark, that would be great. I've been really busy and this is
on the back burner for a few days.

Udo, thanks for the link, looks like good info.
15  Forum 2005-2010 (read only) / Development / Re: New design: MegaSquare using ATMEGA2560 on: March 17, 2010, 11:41:22 am
If you are trying for 2 layers, you will probably have to keep one side mostly horizontal and the other side mostly vertical to have enough lanes left to route the signal traces.
Yes, learning Eagle and learning how to layout a PCB and yes it
is 2 layer. Thanks for the tips, I'll see what signals I can get routed
as is and then move things around as needed.

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