SMD 8m2 Programming

Just venturing into SMD thanks to the excellent milled PCB's available on ebay, great service.

Have the SMD versions of Picaxe got the same downloading technique/capacity as the DIL versions?

Previously I've removed the Picaxe for programming but now I get the "cannot find the device" message after the initial SMD programming?

The serial out pin has an LED attached which flashes when I try and program, presume I need to islolate with jumpers as suggested, just wondering what other folks do to get round it?

An SMD PICAXE should be no different to a DIL version when it comes to download interfacing and programming. A LED+R on the download serial out (C.0) should not normally affect the download process and would not normally need to be isolated with a link jumper.

Having a LED+R in place can be useful to tell if the PICAXE is transmitting; that it flashes during download suggests it is responding to the download.

Isolating C.0 when programming is mostly needed to stop high-speed high and low signals getting to servos, motor and relay drivers or things which might not like those. LED+R's and piezo discs would normally be okay if left in place.

Thanks for the informative reply. Looks like I've got something else adrift.

Tried 2 with same results. Unless of course I've cooked both 8m2 whilst soldering it in with a hot air gun. Any limitations/reccomendations on temp and time?

Is the AXE027 protected against wrong/shorted connections, ie to 0v when programming?

Thanks

I have soldered SMD 08M2 chips with a conventional iron and fine tip without problems.
Usually tin the PCB pads and the IC pins, hold in place while soldering a pin or two.
Then check alignment before soldering the rest.

Many recently were used on some minuscule PCBs (for installation in extremely small spaces with SMD voltage Reg and couple of half H-bridge chips) Intended for native PICs but I have used a PICAXE with my own code.
Been programming in a separate SMD socket before soldering into place. I am doing a mod to the minuscule PCB to bring out the Serial In and use a different pin for one function.

Does your program have a tight loop which might prevent easy reprogramming.
Have you tried a hard reset procedure when trying to download a new program.

JPB33 said:

Is the AXE027 protected against wrong/shorted connections, ie to 0v when programming?

Click to expand...

There are current limiting resistors on the signal lines but the degree of protection would probably depend on what they were exposed to.

A cable test should reveal whether the cable is working or not.

There are 3 broad tests you should do when you can't program a new chip.

1. Test the cable (as mentioned by hippy, above).
2. If successful, when the programming cable is connected to the chip, is the Serial In pin held low and go high when you click the "download" button?
3. If successful, do you see pulsing on the Serial Out pin when you click the "download" button?

Thanks everyone for the advice, points noted. I previously tried the tests as per the manual for the programming cable which it passed. Next step at proving the rest of the gear was a bit backwards as I discovered some dead 8m2 I had in stock which confused things.

The good news is that the hard reset did the trick so I'm dead chuffed about that and pleased I asked!

The only SMD sockets I can see are for larger square ic's, are they available for the 8 or 20m2 as in #4 or am I reading it wrong?

Getting it working has been great but its highlighted another problem which I've updated the original post with.

JPB33 said:

Getting it working has been great but its highlighted another problem which I've updated the original post with.

Click to expand...

It's not clear which 'original post' you are referring to.

Try searching for SOIC8 test socket.

They work by pressing the IC into the socket then press again to release.
Tend to be expensive so only use for the separate programming prior to permanent install.

Here is a breadboard-able example:
http://core-electronics.com.au/smt-test-socket-soic-8-narrow-breakout.html?utm_source=google_shopping&gclid=CN36zfP32s0CFUhwvAodqlwL7g
http://www.elnec.com/products/programming-adapters/DIL8W_SOIC8_ZIF_200mil/

Thanks for the info, it always helps when you know what your looking for! I've got one on order

For those on a tight budget check Ebay. They're available from China at a small fraction of the cost. I can't vouch for the quality though.

Chris

JPB33 said:

Thanks for the informative reply. Looks like I've got something else adrift.

Tried 2 with same results. Unless of course I've cooked both 8m2 whilst soldering it in with a hot air gun. Any limitations/reccomendations on temp and time?

Is the AXE027 protected against wrong/shorted connections, ie to 0v when programming?

Thanks

Click to expand...

are you using the lower temp solder?
http://www.ebay.com.au/itm/SMDLTLFP-LOW-TEMP-SOLDER-PASTE-by-CHIP-QUIK-SHIPS-FROM-THE-USA-/162112466777?hash=item25bea7ef59:g:lIEAAOSwKfVXI7iz

I used to use a hot air gun but these days I use a cheap toaster/griller oven. Better distribution of heat and no air blast to move parts off centre. I just watch until surface tension on the melted solder pulls everything in to line and take them out.

The sockets arrived but I've got the wide version--my mistake but the e bay quality looks good so ordered a narrow one. I cannot at present find a 20 pin version of the socket--are they made or am I just not looking in the right place?

marzan said:

are you using the lower temp solder?
http://www.ebay.com.au/itm/SMDLTLFP-LOW-TEMP-SOLDER-PASTE-by-CHIP-QUIK-SHIPS-FROM-THE-USA-/162112466777?hash=item25bea7ef59:g:lIEAAOSwKfVXI7iz

I used to use a hot air gun but these days I use a cheap toaster/griller oven. Better distribution of heat and no air blast to move parts off centre. I just watch until surface tension on the melted solder pulls everything in to line and take them out.

Click to expand...

Thanks for the tip on he lower temp solder paste. The use use of a grill/oven sounds horrendous to me! But dont dispute it works fine. Marzan, if you read this post can you elaborate a bit more on your techinique please?

20 pin and Larger pin count test sockets are available. Not all come with pre fitted headers to allow immediate use in a breadboard.
https://www.adafruit.com/product/1282
http://www.waveshare.com/ots-2428-1.27-04.htm

As well as SOICxx test socket try programmer adapter.
Xx is no pins of interest.

I can see quite a few including on eBay.

JPB33 said:

Thanks for the tip on he lower temp solder paste. The use use of a grill/oven sounds horrendous to me! But dont dispute it works fine. Marzan, if you read this post can you elaborate a bit more on your techinique please?

Click to expand...

When I worked elsewhere, I used to have to solder some very small SMD inductors that had no legs, just what looked like sliver paint on each of the four corners, on the underside of the ferrite. They were an absolute pain to get soldered as if you managed to catch one corner with solder it tended to slightly lift other corners slightly away from the solder pad meaning that solder would appear to flow onto the joint but was in reality only touching the pad on the inductor. Worse was that they often appeared to work in testing, but would later fail when moved.

I developed a technique where I placed an aluminium slab of about 3cm depth on an old hotplate and used this to heat the PCBs to a heat where you couldn't bear to pick them up by hand. I then would flux the pads, put the inductors in place and allow them to warm up before soldering them. Doing that improved our success rate from 20% to over 70%. Simple things for simple me...

CDRIVE said:

For those on a tight budget check Ebay. They're available from China at a small fraction of the cost. I can't vouch for the quality though.

Chris

Click to expand...

When I posted this I didn't even know that SOIC8 test sockets existed but surmised that they did. The sticker shock price of what was posted prompted me to search Ebay for "SOIC8 test socket". That brought up this page with all these Aligator + Ribbon cable + socket versions.
http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR0.TRC0.H0.XSOIC8+test+socket.TRS0&_nkw=SOIC8+test+socket&_sacat=0
I didn't see the push (load chip) Push (unload chip) with 8 pin DIP interface in those listings. However, there was a "Sponsored Link" at the bottom of the page that brought me to..
http://www.banggood.com/SOIC8-SOP8-To-DIP8-EZ-Socket-Converter-Module-Programmer-Adapter-p-937407.html?currency=USD&createTmp=1&utm_source=ebay&utm_medium=cpc&utm_content=saul&utm_campaign=SKU145216-US&ebay

I couldn't resist the price so I ordered it. It arrived yesterday and I'm happy to say that it looks & works exactly like the images on that page. It's definitely worth every dime!

Chris

Thanks for the info. Iv'e bought this for the 20m2, fits a dil socket a treat and arrived overnight.

http://www.ebay.co.uk/itm/121133541880?_trksid=p2060353.m2749.l2649&ssPageName=STRK:MEBIDX:IT

Also didnt realise the 300mil of the 20m2 refered to 0.3" just presumed it was metric so bit more learned!

Peter

Mils is a term/unit of American origins. Believe that 300mil is 300 thou (= 300 / 1000 inches = 0.3").
Likewise for cross sectional area of cables there are circular mils whereas other region use mm2.

For IC in the DIP pin format, up to 28 pin they Are available typically in the 0.3" spacing between the rows of pins.
With some overlap, from around 24 pins upwards they are available in the 0.6" spacing between the rows of pins.
All DIP packages are typically on 0.1" pin spacing (or multiples of this where there are absent pins such as some relays).

When it comes to SMD Devices there are far more variants.
In SOIC and similar packages (SOT-xx, SC70-xx etc) you can find 1.0 mm, 0.95 mm, 0.65 mm and 0.50 mm pin centerline spacings.
I have hand soldered SOIC devices up to ~32 pins at 1.00/0.95 mm centres. Shortly (when they arrive) about to see if I can hand solder Pins at 0.65 mm centres (with my not so good close range eye sight aided with a magnifier visor).

I cut a solder paste stencil,but most board makers give you the option of making one with your pcb order. You can make a jig with some old pcb strips and some double sided tape to paste multiple boards.then place all the smd components on the board. You dont have to get them perfect as surface tension pulls most of them straight. I set the grill oven to approx 20 degrees over the low temp solder melting point, or max temp for normal solder paste. You get the best results if you use both the top and bottom elements. I watch the boards and as soon as I can see all the solder has melted I turn the oven off and open the door. Let them cool for about a minute and you can start soldering the other components onto the boards. Cooking times are normally in the 4-6 minutes in the toaster oven I use. Dont use it to cook anything ever again after doing pcbs!!