Instructions feedback

USB AVR Programmer and SPI interface. Adafruit's USBtinyISP.

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pstemari
 
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Instructions feedback

Post by pstemari »

I just finished this and after some rework I was able to use it successfully on some GoL boards.

IMHO, the bit about the 1.5K output resistors not being needed is stated too laet and too weakly. It's not until you get to the debugging instructions that there's a fairly definitive statement that you should not install these if you're going to use the USBtinyISP as an ISP.

I'd change this:
Now that you have a lot of practice with resistors, you can do the remaining 5 all at once. Place R10 (10K pullup resistor), R3, R4, R5 R6 and R7 (1.5K resistors for the USB connection, LEDs and output buffer)
to say:
Now that you have a lot of practice with resistors, you can do the remaining 5 all at once. Place R10 (10K pullup resistor), R3, R5, and R6 (1.5K resistors for the USB connection and LEDs). Install jumpers for R4 and R7 (output buffer) unless you are going to use this as a dongle for the SpokePOV. If you plan on using this with the SpokePOV, then install 1.5K resistors for R4 and R7.
This bit at the end:
If you're not using the USBtiny to talk to a SpokePOV kit, and if you are using a target that has some load on the SCK and MOSI pins, you may need to replace R4 and R7 with jumpers as the 1.5K resistors will have trouble driving the load!
is too little too late. At this point, the resistors were long ago soldered in. This bit in the help:
Do you need to 'jumper' the output 1.5K resistors? If you are not using the USBtinyISP for SpokePOV communication, this is recommended, especially with target chips that have something connected to the MISO/MOSI/SCK lines. Check the end of the soldering instructions for how to do this
is much more accurate than the instructions.

fulg
 
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Re: Instructions feedback

Post by fulg »

I almost made the same error (installing R4 and R7 instead of jumpers). I only intend to use USBTinyISP as an ISP. Thankfully I didn't know what I was doing (this was my first soldering kit) so I took the time to fully read the instructions before starting... :mrgreen:

One thing that I had trouble with was soldering the 10-pin connector, the 6-pin header, and the 2-pin jumper. What is the correct procedure for soldering those parts? You can't bend the corner pins like you can with the socket and buffer chip, so I made do with what I could. In the end the 10-pin connector and the 2-pin jumper were soldered at a bit of an angle, because I couldn't hold those parts correctly upside down. I got lucky with the 6-pin header, it was soldered flush.

Surely there's an easy method to do this (simulating your third hand...) to get perfect results everytime... The instructions are almost perfect (hand-holding you at every step, which is great when you don't know what you're doing), but at that step I made some mistakes due to inexperience. Up until that point, my build perfectly matched the reference pictures, which was quite satisfying.

Despite those minor errors my board seems to work fine (USBTinyISP driver 1.12 works fine in Win7 32bit, avrdude from WinAVR sees the programmer correctly). I still haven't received my Atmega board so I have nothing to program yet :)

I had to insert a piece of double-sided foam tape under the USB port, otherwise the board would move around when plugging a cable. Also, the LEDs don't poke out of the casing when using the dimensions provided (1/2"), if I could I would install them a bit higher.

Cheers, and thanks for a great kit, it was a great learning experience (now I know I can solder!). It's almost a shame that it's so quick to build, when I was done I wanted to keep going...

Ben.

antoonh
 
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Re: Instructions feedback

Post by antoonh »

same here. except the wording "may be installed" put me on the wrong track. Didn't feel comfortable with putting resistors in, but also not jumpers. Good thread though, seems to make sense to install jumpers...

Antoon

vxbinaca
 
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Re: Instructions feedback

Post by vxbinaca »

So if I want to program a TV-B-Gone using a target board I need to snip those resistors?

adafruit
 
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Re: Instructions feedback

Post by adafruit »


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tjc61
 
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Re: Instructions feedback

Post by tjc61 »

I'm a software guy, new at this hardware stuff. I was looking forward to programming the chip. I soldered in R4 and R7 BEFORE soldering in the 74AHC125 chip. I attempted to get the R7 out by desoldering with that suction gaget. Major fail couldn't heat the solder and then position the thing over the solder before it started to dry. Attempted to heat the solder, while board was attached to third arm and I pulled on that side of the resistor with pliers. Fail, finally got the one end high enough to snip it. Managed to extract the non-snipped side after much heating and pulling. Now the holes have solder in them and use of a wick has reduced it a bit but the holes are still blocked. Is this desolder business only possible in certain circumstances. Is this fixable? Is there a tutorial on how to juggle the "sucker", the target and the soldering iron? Could you alter the instructions, I suggest that before instructing the soldering of R7 that you instruct the reader to solder in 74AHC125 first, as this is clearly the safer step, regardless of whether the chip is bigger or not. Otherwise it was great.

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adafruit_support_bill
 
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Re: Instructions feedback

Post by adafruit_support_bill »

My favorite technique for using the solder sucker on through-hole parts is to position the tool on the back of the board and heat from the front. When the solder melts, trigger the sucker just as you lift the iron. It takes a bit of practice to get the timing right. This technique also works well for cleaning out holes after removing the parts.

It helps to have a good iron. Lower-power (25W or less) irons will take longer to heat a joint & longer to recover after heating a joint. The longer you spend heating the joint, the more risk of damage to the component or the board. And after repeated melt cycles, the solder does get harder to work.

Also, using pliers directly on the component lead acts as a heat-sink and accelerates the solidification of the joint. I usually (gently) pry under the body of the component to lift the lead from the hole.

I'll refer your tutorial suggestions to the team.

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tjc61
 
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Re: Instructions feedback

Post by tjc61 »

Thank you for this, I will try it first thing in the morning! :)

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tjc61
 
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Re: Instructions feedback

Post by tjc61 »

Hi adafruit_support_bill,

Your explanation on the sucker worked great, I had to look twice, clean holes, used the snipped resistor wires for jumpers. After downloading and installing drivers and AVRDude, reboot, green LED was on. Ran cmd and received the expected -1 response. I did get a brief flash from the red LED. Then I had a bit of a frustrating time as I continued to get -1! Checked the cables, as I removed the 10 pin I noticed the 6 pin was reversed! executed avrdude -c usbtiny -p atmega328p and it worked. Attempted to run test_leds.hex, failed. Seems that when I copied it from the browser window into Notepad, it must have included carriage returns or some such thing. I used the DOS editor and saved it to the root of C:. This time it ran. All works, time to try it out! Thanks again.
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command window showing results
command window showing results
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adafruit_support_bill
 
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Re: Instructions feedback

Post by adafruit_support_bill »

Great! Glad it's all working for you now :D

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