Teensy 4.0, accesing 24 to 33 pines

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We have got two units of Teensy 4.0.
In our project we need to use most of pines so we need to access to pines 24 to 33. Software is easy but, do you know if there are a socket to get contact to this pines? or we have to solder small cables to them?

Thanks in advanced,
I believe you are talking about the relative easier to access pins 24-33.

When I wish to use these, I might use an SMT connector.

You can get specific ones for these that are 2x5. But often times I simply get a kit like the ones sparkfun sells for T3.2: https://www.sparkfun.com/products/13925
And take the 2x7 and remove 2 sets of 2... But again you can find specific ones for this at places like Mouser or digikey.
Something like: https://www.digikey.com/product-detail/en/molex/0015916102/WM3699CT-ND/2421921
Might work
There are several different projects to provide access to the underneath solder pads.

For pads 24-33, the 2x5 SMD headers can be used like MJS513 says.

FRDM4236/Trainer4edu has two different PCB designs that can order from OSH park that brings out the pins in a form factor similar to the Teensy 3.6, including attaching pads 34-39 to a micro SD card reader. One pad brings out the USB host pins, and the other pad only brings out pads 24-39:

In the FRDM board, you will need to order a few surface mount components (capacitors, resistors, micro SD card reader). The board uses castellated cut-outs for the pins, so you need to make sure the PCB fab does the cut out correctly. As the FRDM site mentions, he had some problems with the thinner PBCs getting everything to match up.

Blackketter has a board that brings out the pins in a smaller fashion than the FRDM board, adding a row of 14 pins on each side of the Teensy. Blackketter also has side car PCBs to allow easier addition of the micro SD card reader, USB host, and integration with a ESP32 wifi/bluetooth board.

In soldering the 1mm pads for pads 34-39, IMHO, the FRDM board is slightly easier to solder than the blackketter board.

Talldog (on tindie) and loglow (here) has a board he has been designing that he was planning to sell on his tindie site.

Many of us wish that Paul could get the appropriate parts to announce and sell a Teensy 4.x variant (4.1?) that will have more pins and be in the Teensy 3.6 form factor. But until that happens, you have the various DIY approaches.

The original breakout board was used during the Teensy 4.0 beta test period. It uses pogo pins to access some of the pads in the 24-33 range (but not all pads were brought out), and it uses a FFC cable to bring out the SD pads. One of the main features is providing for a separate pad to allow using a revision A/B/C audio shield with the Teensy 4.0. With the revision D shield now shipping, we don't really need that section of the board.
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One thing - be careful when soldering the smd header. Unlike the the 3.x devices, there are a number of smd devices near the pads and it's easy to hit them even with a very fine tip iron. I managed to hit one of the 402s with the heat and it was gone before I realized it.
I would dearly like to use these additional pins but, the big problem, as I see it, is properly aligning the surface mount pin header so that pins accurately lie on the same 2.54 mm grid as the Teensy. Are there tips for getting good alignment?
I would dearly like to use these additional pins but, the big problem, as I see it, is properly aligning the surface mount pin header so that pins accurately lie on the same 2.54 mm grid as the Teensy. Are there tips for getting good alignment?

Well I imagine that pins 24-33 are aligned to a 0.1" boundary that it would be a matter of soldering in the pins on the external rows. and then use a prototype board to hold the outer pins, and the inner 2x5 pins. Put the prototype board (or maybe a small breadboard) up high enough that you can get the soldering iron to the pads. Put a small amount of solder either on the SMT headers or on the pads, and then use a soldering iron or a small heat source to melt the solder so it flows.

I haven't actually done it with this method. My first attempt was just soldering wires to the pads, and I had the issue that some of the wires came off. In trying to redo the soldering, I managed to lift the copper off of two of the pads.

If you have doubts about your soldering skills, there is a new tindie entry that will sell an Arduino Due compatible shield for the Teensy 4.0, complete with a wifi breakout. One of the options is to have the shop soldering the Teensy 4.0 onto the board. Price is about $70 US including shipping.

On another thread, loglow (talldog on tindie) has said his board is about 30 days away from selling his board. For his 3.2/3.5/3.6 boards, he has had an option for him to solder the Teensy to the board:
What I will often do, is to do what Michael mentions.

In particular I place the external pins into a breadboard and then put the teensy on and solder those pins in.

I then take the Teensy out of the breadboard and turn over and place the smt pins as close to where they should be. I then use some female header that are at least 7 pins wide and I press them over the 5 pins plus the two corresponding pins on the external rows. I do this for both rows of the SMT. This usually holds it pretty much in the right place. And I solder them in.
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