Wednesday, April 18, 2012

Bah,exams again.

I have my final exams for this semester coming up soon,so the next post will probably be in mid-may.

I have quite a few exciting projects to put up,including my work with the Cypress CYRF6936 based AWP24S modules from artaflex,and trying to port Contiki onto PSoC5 using these..Also I'm gonna write about bit-banging UDP using just pure hardware peripherals on the PSoC.Ah,lots to write about.

Back to test prep.

Sunday, April 8, 2012


I've finally made the switch from dumping my zipped up source files into a 4shared account,to hosting them up on Github.

I've already pushed my QuickPSoC3 files up there,and will be migrating all my other code and design files there soon.

Check out the QuickPSoC3 repo here.

Friday, April 6, 2012

Desoldering SMD Parts - No Fancy Tools

So this post is in,well yeah,de-soldering SMD parts without using any special tools or chemicals(ChipQuik looks like TV magic!)
I had a non-working Cypress PSoC3 First Touch Kit (btw,dont ever buy one.I'll do a review sometime soon where I'll tell you why) from which I wanted to remove the 12pin 2mm pitch(when did 2.54 become an unlucky number?) SMD header intended for their CyFi wireless modules made by Artaflex.

The SMD header in question.
 So yeah,Since the kit was badly damaged(too fragile,they are.) I thought it fit to take off this weird header,and use it for my PSoC3 Wireless development board(future project).

As far as soldering equipment goes,I own a cheap 25W iron,and some flux cored solder wire of local make,I think 1mm or so in diameter.Yeah,that's it.

So here is a cool trick that worked.I don't know if its already out there,but I'm documenting it here anyway.

1.Flood the pins with solder,on both sides
solder flooded pins
2.Add enough solder so that each pin is part of this huge glob,on either side.In this case,I removed those anchors(on either edge of the part) using a bit of stiff wire to pry them up while keeping their solder molten with my iron.Then heres the part that needs to be done with some deftness.
keep running your iron's tip along the sides of the part,keeping both solder globs molten long enough to allow you to take off the part with tweezers (if you have them),or you could hold the board at some steep angle,so that the molten solder on both sides cant hold the part against gravity,and it slides off.Thats what I did here.

Off with you head(er)!

In this case I had planted the board onto a breadboard,so I could hold my work easily,and then held that almost vertical,so that the SMD header came off easy when the globs were molten.

A good part about this method is that you leave most of that excess solder on the board,not the part.So thats less of cleaning the part's pins.Thats a big concern if its some close pitch TQFP or something.

3.After a bit of cleaning with some IPA from a friend(Thanks!),heres what the end result is

Easy :-)

Thursday, April 5, 2012


My recent project,the EzPSoC3 caught the attention of the great folks over at DangerousPrototypes,who very generously offered to fabricate my PCB design.Really appreciate it,Ian!
Without further delay,here are a few pictures of the shiny red PCBs!

I have populated this board,but it doesn't look too good with all the flux residue.I'll get some solvent,clean it up and post a few pics soon.

Thanks for supporting this first real open-source project of mine,and I'm really happy it worked out so well.First PCB,First Power-on,and it worked!

Wednesday, April 4, 2012

MicroSD Card Module from EmbeddedMarket - Review

I recently acquired a MicroSD card module from,and heres a product review:
Image credit to

1.Product Page & Ordering:
As of the time of writing this post,the price listed on the website is INR 225,which is on the quite okay for a module like this,and its totally worth it,considering the quality and other details I'll elucidate here.

2.Packaging and Delivery:
The purchase was smooth,and I faced no hitches during payment or such.Within a few hours of placing my order,the product was shipped,and theres also a 'Real Time Order Ticker' that displays the status of various orders.It was shipped via DTDC India,and a tracking code was promptly provided.Shipping from Pune to Goa took a mere 2 days,and I recd. the product in a hard brown cardboard box.Safely within scrap paper, the module was in a small hard plastic box,in sealed antistatic.Really good stuff,I must say.The plastic box is a good touch.They score high on packaging and delivery.

3.The module:
Coming to the actual hardware,the PCB etc was quite good in terms of quality,silkscreen legibility etc.My module did have a solder short between C2 and R7,but it passed the QC because that short was parallel to a track on the board connecting those two.Anyway,an error like that was a little displeasing to see.
I opened a support case with them,and quickly clarified this matter.Only problem is that you receive no email notifications about a reply from their support staff.You need to manually go check.Anyway,Their support is quite prompt,and quite satisfactory,and I was pleasantly surprised about the same.

The module itself has a couple of good points,over any socket-on-pcb type crappy modules.
-It has support for 5V as well as 3.3V interfacing,which in my opinion is a resounding +1 for them.

-A very important power LED is also there on edge,right near the SD card slot.A power LED is always a must in my opinion,however small the module or board is.The placement too is well thought out,since it being on the edge and near the SD card slot, can be made visible through any enclosure etc.

-The 4 important SPI lines are placed consecutively.I mention this specially because on an ENC28J60 Ethernet module I bought from them an year ago,the pins aren't.But here that's not the case,and one may use a 4pin female to female cable to connect the module to the relevant control circuits.

-The silkscreen text is good and helpful too,indicating polarity etc where required.

-2 diagonally opposite PTH type mounting holes,which are not physically connected to any net on the board,or each other.Mounting holes,a +1.

-The board takes 5V DC input from 2 pins near the corner of the board.Heres one thing I'd like to point out..Infact this is the only minus point here according to me.The 2 pins for 5V power,and the remaining 8 pins do not maintain breadboard pitch between them.What I mean is,the distance between the 2 headers should be some multiple of 0.1",so that the entire edge can be inserted into a mini breadboard's edge,or a socket for the same on a PCB you make can be designed easily,but its not.So you have no option but to use wires to interface.Bah.A definite minus point.

-The silkscreen says DI and DO for the SPI datalines,so do note that this DI/DO  convention requires that DO(MOSI) on the master be connected to DI on the slave, and vice-versa.This is mentioned clearly in the module's manual(PDF) too.

-Oh and the module includes the 4 jumpers required for 5V interfacing selection.
-Also I feel they should keep the headers un-soldered,but supplied so that one may solder other wires/female headers if they want,or use the male ones supplied by default.

End Verdict: I have successfully used this without any hitches with a PSoC3 board of mine(post on that soon!),and I am happy(except for that pitch issue.) with this product,and would definitely recommend it.

They keep a useful range of modules,and its worth a browse.Check them out here.

The MicroSD Module Page is linked again,here.

QuickPSoC3 - V2

So,I'm back,after a long pause,mainly due to my HDD crash and tests,exams and such.
Anyway,This post is about an improved QuickPSoC3 layout,
Heres a brief list of the changes:
-Longer pads(almost 3x) so it makes soldering the SSOP part easier for beginners.
-Widened power tracks to 70mils
-Arranged pins(see top-right) such that the miniprog3 can be directly plugged in,making programming easier
-The miniusb connector now is the variant without the plastic pegs beneath.
-Added one user programmable LED(in 1206) and push button switch.
-I'm not using the sparkfun library anymore,since many users complained their pads are too small to solder stuff comfortably.
Another point is that the SMD passives can be easily replaced by their through hole variants,and can be made 100% through hole,excluding of course the chip itself.

Adding a USB bootloader to this design simply involves taking the stock boot-loader in PSoC Creator 2.0(now with Component Pack 2!) and switching the device to the relevant one used.

The files are made in Eagle 6.1 Lite Edition,and can be found linked from my 4shared account here.
Linked over from the thread at PSoCDeveloper forums,here.

EDIT : An updated version is also hosted on my github repo here.