1
Show Posts
This section allows you to view all Show Posts made by this member. Note that you can only see Show Posts made in areas you currently have access to.
Messages - somun
2
General discussion / Re: Groundloop blowups
In my case, I had connected the ground for the switching motor driver circuit to the ground of the microcontoller board without much thinking given they were both earth referenced grounds. However the motor driver's power connections were coming from quite thin and long cables (this is not a high current application) so by connecting the two grounds together I had given the motor drive circuit a much lower impedance alternative and all the switching noise ended up messing with the digital side. I removed the ground connection and things got normal.
3
Project development, ideas, and suggestions / Re: Cheapest USB microcontroller arduino-able alternative?
http://ww1.microchip.com/downloads/en/M ... _Final.pdf
For the lowest cost, PIC16F1459 might be the best fit. It is less than $2 and available in DIP, SOIC, SSOP and QFN.
4
Project logs / Re: Cheap DIY Usb Blaster compatible programmer
Did you make it using toner transfer or photo resist? How small traces can you go? :P Seems to me those are 8 mil traces.
I like the surface mount headers, and the way some of the resistors are placed at what appears to be 45 degree angles! Did you make this board using eagle or Altium?[/quote]
Thanks! It's toner transfer. After I got rid of the clothing iron and modified a cheap laminator for the transfer process I can say it's a whole new experience :) Those traces above were 10-12 mils actually but 8 mils is no problem either. Attached is a snapshot of a board with 8 mil traces - that's a nasty EQFP-64 package there (the issue on the top-right was a careless mistake in etching).
[attachment=0]
Surface mount headers are DIY. I simply took some right angle headers, rotated the longer side pins, cut the pins to size and ta-da :)
I am using Eagle for all my boards. You can place components in any arbitrary angle actually. Simply type in the angle while moving the component (or use the rotate tool ;p).
[attachment=1]
I intend to share some more stuff regarding DIY PCBs, hopefully soon.
5
Project logs / Re: Cheap DIY Usb Blaster compatible programmer
This is sort of an older version. The new one is using a cheaper 18F14K50 (but I did not have that). It is only 3.3V compatible but that can be easily handled by adding some level shifters. It's a simple design with just the micro and some passives but I can share my Eagle files if anyone is interested.
[/quote]
Pretty sure that you can easily do a 5V 14k50 version or even a 5V/3V switchable version. The advantage of the 14K50 is that it can run at 12MIPS @ 3V, the 2550 cannot.[/quote]
Good point. If I were to build another one I would definitely take care of the voltage translation part. The jtag header carries the IO voltage of the device to be programmed so a transceiver powered from that would work with all voltage levels.
[quote author="kiranjose"]I have a PIC18F14K50 dev board. I downloaded the hex file into it and connected the USB. QuartusII detects it as USB blaster. Wow!![/quote]
Yep, I was amazed, too.
[quote author="kmmankad"]waiting eagerly for a scoop on your Max V CPLD board :)[/quote]
That one coming up soon :)
[quote author="ginpb"]Awesome, can i have the eagle files.
Do you tried the Openocd firmware present on the original website?[/quote]
I did not see or try the Openocd firmware there.
I attached the Eagle files.
6
Project logs / Re: PSoC3 Custom Board
7
Project logs / Cheap DIY Usb Blaster compatible programmer
I've been trying to get my hands dirty with programmable logic for a while now and naturally at some point I faced with the reality that I needed a programmer. For some semi-random reasons I am inclined towards Altera devices rather than the more popular Xilinx . My choices were; Buy an Altera USB Blaster ($300 !), buy a Terasic USB Blaster clone ($50 + shipping from Asia), get some Chinese clone on ebay ($10 - $30). Actually $10 also includes shipping and looks like a great deal. However I did not want to wait for 2 weeks for shipping.
Anyway while searching online for DIY options, I came across this page which shows a very simple looking one with a PIC18 on it. It is in Japanese but, google translate was my friend :) I was not sure if it would work but I had a 18F2550 laying around (plus I had built a Pickit 2 clone a short while ago) and decided to give it a shot. To my surprise it actually worked.
[attachment=0]
This is sort of an older version. The new one is using a cheaper 18F14K50 (but I did not have that). It is only 3.3V compatible but that can be easily handled by adding some level shifters. It's a simple design with just the micro and some passives but I can share my Eagle files if anyone is interested.
Here's the link to the original page (I am using Chrome so it automatically prompts for translation to English):
http://http://www.sa89a.net/mp.cgi/ele/ub.htm
p.s. The board on the right is my Max V CPLD board which I plan to post about soon (it is a two sided board with non-solder via's, more on that later ;p).
8
CPLD programmable logic / Re: Coolrunner beginner,programming???
9