Another Teensy 4.0 Breakout Board

[blackketter]

I've just got back a Teensy 4.0 breakout board that I ordered from OSHPark and thought I'd post about it.

This board solders directly to the back of the Teensy 4.0 and uses some castellated (i.e. cut) holes to connect to the pads on the bottom. It brings these out to two additional columns of 0.1" header on the outside of the board.

This includes:

• SD
• USB Host
• Pads 24-30 on the bottom
• Five pins along the end: On/Off, Program, GND, 3.3V & VBatt

Looks like this:



Front and back of the board:


Top and bottom with breakout board attached:


Close up of pads soldered to castellated pads:


Bonus using right-angle headers:


I've tested continuity on all the pins and it seems to work without shorts. Soldering the castellated connections was a lot easier than I expected.

I haven't soldered the headers on yet because I'm waiting on an order from digikey with some headers with longer pins on the "top" to make sure I can make solid connections through both boards. (Next time I'll order 0.8mm thick boards and shouldn't need special headers.)

I've posted the KiCad project here if anybody wants to take a look. It uses the SMD footprint from here.

If you are interested, you can order yourself up some from OSHPark here. $6.30 for a set of 3 delivered in the US.

A variation of this could include an SD card slot and/or USB host connector. I built it as a proof of concept for a larger board with a bunch more peripherals, I'll detail that in another post later...

Let me know what you think!

[firehopper]

its interesting.

[defragster]

Very cool looking! Wasn't sure the SDIO spacing would work that well

OSH doesn't show pin map but github.com/blackketter/teensy4_header_breakout does.

Looking at :

Right Side Pinout:
VUSB
USB Host D-
USB Host D+
NC
NC

If the two NC's were GND - it would fit this connector for USB Host given the other pins in place.
pjrc.com/store/cable_usb_host_t36.html

[blackketter]

Very cool looking! Wasn't sure the SDIO spacing would work that well

OSH doesn't show pin map but github.com/blackketter/teensy4_header_breakout does.

Looking at :


If the two NC's were GND - it would fit this connector for USB Host given the other pins in place.
pjrc.com/store/cable_usb_host_t36.html

Thanks!

And that's a brilliant observation on the header connector. I'll make the change to the design now.

[Theremingenieur]

Just ordered. Added 2 purple Teensy4.0 and got free shipping to France

Planning to solder the default T4 pins from the bottom side to keep it breadboard compatible, and the outer pin rows from the top to ease DuPont wire connections.

[defragster]

@blackketter - hope getting GND over works out - looking forward to order.

Just ordered. Added 2 purple Teensy4.0 and got free shipping to France

Planning to solder the default T4 pins from the bottom side to keep it breadboard compatible, and the outer pin rows from the top to ease DuPont wire connections.

... perhaps ordered too quickly - new and improved version pending I was going to do that ordering as well - but not to France.


QUESTION:
On these sandwiched boards what soldering order/process works to assure the pins (with header strip in the way) gets soldered properly to both boards?

[Theremingenieur]

I don’t plan to use the USB host for the moment, thus a non-issue for me...

[MichaelMeissner]

Thanks!

And that's a brilliant observation on the header connector. I'll make the change to the design now.

Yes, I was about to put in an order for a Teensy 4 + boards (I've sort of wrecked some of the pads underneath one Teensy). Let us know when it is uploaded (or, I can just manually connect the pins to ground).

[blackketter]

@blackketter - hope getting GND over works out - looking forward to order.



... perhaps ordered too quickly - new and improved version pending I was going to do that ordering as well - but not to France.


QUESTION:
On these sandwiched boards what soldering order/process works to assure the pins (with header strip in the way) gets soldered properly to both boards?

The idea is that you solder from the top of the sandwiched boards. The inner pins are soldered directly to the Teensy, the outer row is soldered directly to the breakout board. which connects to the soldered pads on the bottom.

There are two exceptions:

- The VUSB pin needs to be soldered on both sides with a bit of wire in the middle.
- Your suggestion about the ground pins means that soldering from the top will depend on capillary action to move the solder to the bottom board.

Similarly, if you want to solder from the bottom, then you'll need to make sure that you give it plenty of solder, heat and time to make it to the other side. And make sure you test the connection.

[defragster]

I don’t plan to use the USB host for the moment, thus a non-issue for me...

Also that direct connect method will be missing some electronic support for proper function - a buffer cap and a power surge protector chip? So for proper safe function would require some added parts somewhere. At least the needed pins will be present in order.

@blackketter - reading the github is says "Don't forget to cut the VIN to VUSB trace before attaching board." - that would assume external power expected - or a jumper on top to get the VUSB back to VIN?

[KurtE]

As mentioned looks interesting. A few days ago I started playing with some ideas for a castellated setup. At the time I was think two different ones. One for front and one for rear.
But did not get around to finishing it.

I was afraid of the SDCard pins area. At the time I was playing with the idea of maybe trying do have two cutouts, one at each end and alternate the logical pin connections, for each end, wondering if that might reduce the chance of solder bridges. But it started to feel like it was more trouble than it was worth.

But may have to try one of yours and see how it feels. Is there any indication of which pins if any of the exterior Teensy IO pins connect up to your board?

As for USB host, I am assuming that you have no place on your board to put the USB Power chip and Caps, So even if you added the GND like connections to match up to an USB Host connector, you might want/need to run them to different board to handle this... Although you can probably get away with having the USB device plugged in when the Teensy boots...

But again will be fun to see how well they work.

[blackketter]

Also that direct connect method will be missing some electronic support for proper function - a buffer cap and a power surge protector chip? So for proper safe function would require some added parts somewhere. At least the needed pins will be present in order.

That's right. I'm adding a note to this effect on the Github page.

@blackketter - reading the github is says "Don't forget to cut the VIN to VUSB trace before attaching board." - that would assume external power expected - or a jumper on top to get the VUSB back to VIN?

Right. Only cut it if you need it cut. And do it before you solder the thing together and can't anymore. Like I did.

[blackketter]

Is there any indication of which pins if any of the exterior Teensy IO pins connect up to your board?

Just the GND pin with the change suggested by @defragster.

As for USB host, I am assuming that you have no place on your board to put the USB Power chip and Caps, So even if you added the GND like connections to match up to an USB Host connector, you might want/need to run them to different board to handle this... Although you can probably get away with having the USB device plugged in when the Teensy boots...

That's right. There's no ESD or power protection there. @loglow's board would be better in this situation.

But again will be fun to see how well they work.

Great, please post your experience if you end up giving it a try.

[blackketter]

Let us know when it is uploaded (or, I can just manually connect the pins to ground).

I'm not sure when I'll be uploading another order, but you can grab the latest version here and upload it to OSHPark to order it directly.

Otherwise, hooking up the ground pins should be pretty straightforward.

[defragster]

I'm not sure when I'll be uploading another order, but you can grab the latest version here and upload it to OSHPark to order it directly.

Otherwise, hooking up the ground pins should be pretty straightforward.

OSH took 'teensy4_header_breakout.kicad_pcb' from github and it looks right. Looking at the 0.8mm board with 2oz copper - you noted thinner board 'next time' …

[blackketter]

OSH took 'teensy4_header_breakout.kicad_pcb' from github and it looks right. Looking at the 0.8mm board with 2oz copper - you noted thinner board 'next time' …

That's what I'd do. Should be easier to solder and standard pin headers should protrude though the Teensy holes a bit more.

[defragster]

That's what I'd do. Should be easier to solder and standard pin headers should protrude though the Teensy holes a bit more.

Done! 3 boards at $6.30 per batch of three 2 oz copper, 0.8mm thickness

[MichaelMeissner]

Done, 2 Teensy 4.0s, plus the 3x breakout pcb's. I wonder how many of today's layout are of this board (and adding on Teensy 4.0's).

[WMXZ]

that is what I was looking for.
A longer version with the uSD Card would be great.

[defragster]

that is what I was looking for.
A longer version with the uSD Card would be great.

I was wondering about another level daughter card. It would be 9 pins wide to pickup both edge signals with open 0.7" inside to place SD socket and USB connect cable pins or female USB, and the needed caps and USB power/esd. It could fit top or bottom and need to be 8 pins long to get the SDIO pins, USB only uses 4 or 5 on the other side. Could mount above or below depending on layout.

Left Side Pinout:
34/SD DAT1
35/SD DAT0
GND
36/SD CLK
3.3V
37/SD CMD
38/SD DAT3
39/SD DAT2

[WMXZ]

I was wondering about another level daughter card. It would be 9 pins wide to pickup both edge signals with open 0.7" inside to place SD socket and USB connect cable pins or female USB, and the needed caps and USB power/esd. It could fit top or bottom and need to be 8 pins long to get the SDIO pins, USB only uses 4 or 5 on the other side. Could mount above or below depending on layout.

another valid option.

[blackketter]

Wow, great minds think alike! I started working on just this kind of thing and then read your message, @defragster!



The idea is that it would stack on the existing board with a header connecting. You could even use longer pins and flip it or rotate it to be over or under the Teensy.

[defragster]

Wow, great minds think alike! I started working on just this kind of thing and then read your message, @defragster!

...
The idea is that it would stack on the existing board with a header connecting. You could even use longer pins and flip it or rotate it to be over or under the Teensy.

Indeed just like that - Nice image, is an onboard cap called for? Now I see how that detect switch works.

My non-image was 3 wider to the second side adding cap/chip pads for USB and 5 holes for that connector - or standard female USB off the end. Ideally WiFi dongle support will work out so that is an option.

[blackketter]

My non-image was 3 wider to the second side adding cap/chip pads for USB and 5 holes for that connector - or standard female USB off the end. Ideally WiFi dongle support will work out so that is an option.

I was thinking about doing another similar board for the other side with a USB A host connector and TPD3S014 current limit switch.

BTW: I've ordered the SD breakout and posted it here.

[defragster]

I was thinking about doing another similar board for the other side with a USB A host connector and TPD3S014 current limit switch.

BTW: I've ordered the SD breakout and posted it here.

Good work - fast. So a CAP isn't called for to support the SD power needs? Loglow breakout has 3 caps - one for USB - I assumed one was for SD.