Test clips for 32-TQFP package? - Page 1
Forum section: electronics / projects

author: zapta
author_rank: Super Contributor
timestamp: January 20, 2014, 09:45:13 am
content: Are there in circuit test clips for 32-TQFP packages? For example something like this onehttp://www.warwickts.com/5733--pomona-32pin-plcc-test-clip-p545I am designing a PCB for with a atmega328P avr and would like to avoid the ICSP header area.

author: jeremy
author_rank: Super Contributor
timestamp: January 20, 2014, 10:32:24 am
content: Plenty:http://www.aliexpress.com/wholesale?SearchText=qfp+32+socket&opensearch=true

author: rolycat
author_rank: Super Contributor
timestamp: January 20, 2014, 10:53:37 am
content: Quote from: jeremy on January 20, 2014, 10:32:24 amThose are sockets designed for loose chips, not in-circuit testing.I think zapta is looking for something likethis.CLIP-032-QF59-4 is a snip at $719.48. Not in stock at the moment, though.

author: Rerouter
author_rank: Super Contributor
timestamp: January 20, 2014, 11:07:16 am
content: why not just leave pads and pogo pin to program? just as i cannot see that being any harder than wiring up a qfp32 test jig

author: Dago
author_rank: Frequent Contributor
timestamp: January 20, 2014, 11:13:40 am
content: Quote from: Rerouter on January 20, 2014, 11:07:16 amOr use some smaller connector for programming (like 1.27mm pitch pinheader for example) and use a custom programming cable if space is an issue (I kinda doubt it since you're using a TQFP packaged MCU).

author: jeremy
author_rank: Super Contributor
timestamp: January 20, 2014, 11:55:27 am
content: Quote from: rolycat on January 20, 2014, 10:53:37 amAh my mistake, sorry. Did not read closely enough.Alternative: have you thought of using bootloaders instead? You can boot off SPI, I2C, UART, SD card, whatever you like! Assuming you already have some IO, it means you don't need to add anything to the PCB. You can also put headers on a side-board which can easily be cut off from the main board.

author: Circuitous
author_rank: Unknown
timestamp: January 20, 2014, 01:26:23 pm
content: I too could use similar clips for a couple of packages, but haven't found quite the right sizes.Quote from: jeremy on January 20, 2014, 11:55:27 amI'm curious, how are bootloaders relevant in any way to the OP question?

author: hlavac
author_rank: Frequent Contributor
timestamp: January 20, 2014, 05:46:22 pm
content: Quote from: Circuitous on January 20, 2014, 01:26:23 pmQuite. Microcontroller manufacturers provide preprogrammed chips service.If you have some sort of external I/O you could use it with a bootloader to program the firmware in system by having the bootloader preprogrammed.Some chips with USB hardware (ATmega32U4 for example) come with USB bootloader by default!

author: Circuitous
author_rank: Unknown
timestamp: January 20, 2014, 05:55:45 pm
content: Quote from: hlavac on January 20, 2014, 05:46:22 pmI know what a bootloader is, how it works, and why I might use it for a project.But, once again, how is even the concept of a bootloader relevant to the search for TQFP clips?Many, if not most embedded applications, don't use bootloaders (Arduino weenies excluded). Even if a bootloader is used, that doesn't change the need to probe the chip.Back to the OP question, any sources or recommendations for TQFP clips?

author: hlavac
author_rank: Frequent Contributor
timestamp: January 20, 2014, 06:10:36 pm
content: OP wants to use the clip to program the microcontroller connecting the ISP lines to it thru the socket instead of the dedicated ISP connector footprint he wants to avoid.Just suggesting cheaper ways to do it

author: FrankBuss
author_rank: Unknown
timestamp: January 20, 2014, 06:22:05 pm
content: If you don't need it to optimize for fast production, you could use some of these SMD grabbers:http://www.digikey.com/product-detail/en/72902-0/501-1172-ND/1196307Works down to a pitch of 0.5 mm. Another idea is to use pogo pins and a programming jig:http://www.adafruit.com/blog/2010/06/10/how-to-make-a-pogo-pin-testing-jig/Instead of holes, you could place the ISP connection on the bottom side of the PCB, under the chip, as SMD pads. There are all kind of different pogo pins for this kind applications.

author: attie
author_rank: Contributor
timestamp: January 20, 2014, 07:02:37 pm
content: I think this is what you're after?http://www.hobbyking.com/hobbyking/store/__27195__atmel_atmega_socket_firmware_flashing_tool.html

author: hlavac
author_rank: Frequent Contributor
timestamp: January 20, 2014, 07:26:20 pm
content: Wow, great find attie$19.99

author: attie
author_rank: Contributor
timestamp: January 20, 2014, 08:20:35 pm
content: If you're designing the board, rather than performing a bit of reverse engineering, then there also these guys:http://www.tag-connect.com/Awesome concept, and I've had good results (generally try to use the 'with legs' variants for reliability of connection - otherwise you have to hold the pogo pins down).

author: zapta
author_rank: Super Contributor
timestamp: January 21, 2014, 06:21:58 am
content: Great information. Thanks everybody. I will start with the Hobby Kind adapter (just placed an order), will hook it to my AVRISP MKII (may need to adapt the wiring). The Pomona micro grabber is also very interesting, I think I will get one for testing purposes and see how well it will work. The tag connect is a good option for a small footprint adapter, e.g. to connect to a boot loader. The legless version takes little space and seems to be better centered than common pogo arrangements (e.g.https://www.sparkfun.com/products/11591) and are available for sale at Microchip, will keep it bookmarked.

author: codeboy2k
author_rank: Super Contributor
timestamp: January 21, 2014, 08:12:16 am
content: If I'm space tight, I've also done fingers at the edge of a board and used pogo pins or a clip-on clamp for programming.I almost never want to put a 0.1" header on anything these days unless the board is extra roomy like a big sedanBut almost always there is no good reason to waste real-estate on a programming header anymore.

author: zapta
author_rank: Super Contributor
timestamp: January 21, 2014, 08:22:28 am
content: Quote from: codeboy2k on January 21, 2014, 08:12:16 amWhat kind of clip-on clamp?

author: codeboy2k
author_rank: Super Contributor
timestamp: January 21, 2014, 01:10:05 pm
content: Quote from: zapta on January 21, 2014, 08:22:28 amA big plastic clothes pinseriously. Nothing professionally available, so I made it up. Make the target PCB with fingers near one edge, spaced 0.1" apart, then make a clothespin with a 0.1" header in its jaws , using the the bottom side (small pins) to clamp onto the PCB and "bite" into the fingers, and the longer side of the header for soldering wire to. It's really quick to clamp onto a board for a quick ICSP download when producing a dozen or so boards.I did it at a company lab I was at before so I don't have this here, but it was similar to this one:

author: dannyf
author_rank: Super Contributor
timestamp: January 21, 2014, 03:59:37 pm
content: QuoteHow about discrete, individually placed pins on the pcb? How about another atmega with programming algorithm + the hex file? Piggy-back it onto the target - the pins are perfectly aligned - and power it up. The atmega on top will then program the target underneath it.Or a bootloader for a total software solution.

author: free_electron
author_rank: Super Contributor
timestamp: January 21, 2014, 04:09:43 pm
content: Tagconnect. Put on the backside of the board.

author: zapta
author_rank: Super Contributor
timestamp: January 22, 2014, 04:30:00 pm
content: Quote from: free_electron on January 21, 2014, 04:09:43 pmIt's very nice, especially the no-leg version, but expensive, $47 shipped. I am designing open hardware and trying to minimize the cost of the requirements.

author: alank2
author_rank: Super Contributor
timestamp: March 20, 2015, 01:23:14 am
content: I know this is an old thread, but I made up an inline isp 50 mil connector for small pcb's. I can often fit this under an ic like an attiny1634 for example. No need for pogo or springs, just make small through holes and put the pins in and hold at a slight angle to make contact. I think I ordered like 9 of these pcb's from oshpark for 74 cents delivered. You'll probably have to buy some single row 50mil header to break apart too.

author: zapta
author_rank: Super Contributor
timestamp: March 20, 2015, 02:11:10 am
content: I ordered recently pogo pins from eBay and they are inexpensive and work well, a few bucks for a bag of 50. If you want the to fit in standard header holes, pick the ones with 1.02mm at the soldering end.You are right, OSHPARK is a steal for small boards.

author: alank2
author_rank: Super Contributor
timestamp: March 20, 2015, 02:13:49 pm
content: If anyone wants to use what I am calling mini isp (50mil inline isp), here are the gerbers and info:cost to implement on a pcb ($0)40 mil pad diameter24 mil hole drill50 mil spacingExample of putting this isp header on the other side of a tiny1634:some 50mil header (you can make 8 2x3 100mil to 1x6 adapters with this):S9014E-50-ND $3.60 @ digikey60 cents for 3 pcb's at oshpark (including shipping!)gerbers:http://home.earthlink.net/~alank2/mini_isp.zipGood luck,Alan