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Author Topic: ZIF board for uploading sketches (ArduinoISP)  (Read 2674 times)
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Rather than be constantly taking chips in and out of my Uno, I'd like to build myself up a board with a ZIF socket on it just for programming ATMega328 chips.  I've come up with a quick schematic and have a few questions.

From looking at the standalone breadboard arduino page on here, and checking pinouts for ISP and FTDI connections, this is what I've come up with for the Schematic.


Note : C3 should actually be 0.1uF - I knew I'd make a mistake, heh

Does this look right to you guys?  Or have I screwed something up?  Should I add a reset button?

Presumably if I wanted to use my Uno as an ISP to bootload chips, going by the info here, I'd just hook pins from the ISP header to the Arduino as follows...

1 - Pin 12
2 - 5v
3 - Pin 13
4 - Pin 11
5 - Pin 10
6 - Gnd

It would take all the power it needed from the Uno, I wouldn't require another power source, and it will automatically reset itself (with the 10uF cap to stop the Uno's reset), and job done?

For the FTDI, with having pin 6 hooked up to the reset pin, can I just hook the SparkFun FTDI breakout to that header, and it'll auto-reset on upload using the Arduino software?  Or do I need to add a reset button there and hold it down manually while sending up the sketch? (any way around this if so?)  I'm assuming, again, that it will take all the power it needs via USB and won't require another power source?

In the Arduino software, as I plan on using the Optiboot bootloader, would I just tell it that I'm uploading the Sketch to an Uno?

Also, how would I go about hooking up Tx/Rx LEDs to this so I can see when uploading a sketch via the FTDI is complete?
« Last Edit: June 19, 2011, 09:24:15 pm by Kaouthia » Logged

John

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Does this look right to you guys?  Or have I screwed something up?

One error I noticed is that the signal reset for pin 5 of the ISCP connector is going to the wrong side of the cap, it should wire to reset pin of the processor. The cap is to couple the FTDI DTR reset pulse to the processor, it's not the reset signal. Also not sure you need that C4 10mfd cap on reset, it might screw up the auto-reset timing. There is a new beta Uno bootloader hex file avalible that solves the needing to defeat auto-reset on a Uno being used as a ISP programmer, so the cap or low ohm resistor 'fix' is not required nor desirable, see:

http://arduino.cc/forum/index.php/topic,64105.msg468857.html#msg468857

I built something like that for use with my USBtiny programmer:


By leftyretro at 2011-05-24

Lefty

« Last Edit: June 19, 2011, 10:09:37 pm by retrolefty » Logged

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Ahh ok, so like this then?



Any more obvious screw-ups? smiley
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It's a bit dangerous tying AREF directly to +5V and what is the purpose of R2?
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Did you know about http://evilmadscience.com/productsmenu/tinykitlist/253 ?
If not, it might save you some trouble.  If you're set on making your own, you might find their published schematics/etc useful anyway...
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Where are the bypass capacitors?

Don
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It's a bit dangerous tying AREF directly to +5V
Ok, could you please explain how?  This shows AREF and VCC clearly both going to 5v.

and what is the purpose of R2?
You tell me, it's on here, and a couple of other examples I found.

Did you know about http://evilmadscience.com/productsmenu/tinykitlist/253 ?
If not, it might save you some trouble.  If you're set on making your own, you might find their published schematics/etc useful anyway...
I did not, thank you for that.  Will have a good look over that one. smiley

Where are the bypass capacitors?
So I still need a cap between 5v & Gnd, even though it's being powered by the Arduino?
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So I still need a cap between 5v & Gnd, even though it's being powered by the Arduino?
In general for reliable operation of any digital IC you need a bypass or decoupling capacitor as close to its power pin as possible.  If the IC has more than one power pin then you need more than one capacitor.  Atmel recommends one for the AVcc pin as well.

Don

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It's a bit dangerous tying AREF directly to +5V ...
Why?

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... and what is the purpose of R2?
I think it may help isolate things if you want to use the I/O pin for some other purpose (after downloading your code) while still leaving the USB cable connected for power.  It won't hurt anything, my Bare Bones Board has one.

Don
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So I still need a cap between 5v & Gnd, even though it's being powered by the Arduino?
In general for reliable operation of any digital IC you need a bypass or decoupling capacitor as close to its power pin as possible.  If the IC has more than one power pin then you need more than one capacitor.  Atmel recommends one for the AVcc pin as well.
Ok, thank you.  I did a bit more reading up on them after your last post, so I think I get it now. smiley

Should I be using bypass caps then with 74HC164 shift registers driving HD44780 LCDs too?
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Ok, could you please explain how?  This shows AREF and VCC clearly both going to 5v.

That is not a safe thing to do, regardless of them showing it. The default reference voltage for the arduino A/D converter is already set to be +5vdc via selecting whatever voltage is wired to the Avcc pin. The danger is if a sketch program attempts to select the internal band-gap reference while there is a voltage on the Aref pin there will be current flow through the Aref pin and damage. Just leave the Aref pin disconnected, or wire a .1ufd bypass cap from that pin to ground for a slight noise reduction improvement for AnalogReads.

Read the section labeled Warning in the this page:

http://arduino.cc/en/Reference/AnalogReference

Lefty


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Thanks Lefty, looks like there's a fair bit of conflicting info in the articles contained on this site.  Can be tough for us new guys to sift through and figure out what's "right" (or just recommended - and why) sometimes. smiley
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Thanks Lefty, looks like there's a fair bit of conflicting info in the articles contained on this site.  Can be tough for us new guys to sift through and figure out what's "right" (or just recommended - and why) sometimes. smiley

you're not wrong there!

btw where did you get that ZIF socket
they seem to be exchangeable for 1 arm + 1 leg !
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btw where did you get that ZIF socket
they seem to be exchangeable for 1 arm + 1 leg !
Oh yes Mike, I spent a good while looking around and saw many for £7-8 or so (+shipping).

Then I found 'em on Proto-Pic.  I didn't need the ZIF sockets at the time, but figured I would eventually, so as I was ordering a bunch of other stuff from there anyway, I added a couple to the order, only £2.18 each (inc VAT!).

http://proto-pic.co.uk/products/ZIF-Socket-28%252dPin-0.3%22.html
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btw where did you get that ZIF socket
they seem to be exchangeable for 1 arm + 1 leg !
Oh yes Mike, I spent a good while looking around and saw many for £7-8 or so (+shipping).

Then I found 'em on Proto-Pic.  I didn't need the ZIF sockets at the time, but figured I would eventually, so as I was ordering a bunch of other stuff from there anyway, I added a couple to the order, only £2.18 each (inc VAT!).

http://proto-pic.co.uk/products/ZIF-Socket-28%252dPin-0.3%22.html

rock on that's terrific
award yourself a virtual beer! (or subsitute your beverage of choice)
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