Feather teensy 3.x adapter - Do I lose ports 24-33?

[AgTerra2020]

When using the Feather adapter for the Teensy 3.2, will I lose access to / use of ports 24-33? I'm looking a the adapter and I don't see any support for those pins on the back of the Teensy board.

[michaelmeissner]

It depends on how you wire up the feather adapter to the Teensy. If you solder the Teensy directly on top of the feather adapter, then yes you would lose access to the pads.

You could solder jumper wires to connect the pads before connecting the Teensy to the feather adapter, and bring those wires out.

You could also wire the Teensy under the feather board using either stacking headers on the Teensy or female headers mounted underneath the feather with male pins on the Teensy.

In fact, I'm currently deciding how to wire up my Teensy, Prop Shield, and Feather adapter (and whether I want to solder them together or use stacking headers). Over at the PJRC forum (Teensy home forum), a user FrankB has made a little PCB that is soldered under the Teensy, and it has cutouts that you apply solder to connect the bottom pads, and it brings out the bottom pads as a 2x7 row that juts out behind the Teensy. I've played around with it, and you can put this board under the Teensy and solder it directly to the feather adapter. You could use the short female headers (https://www.adafruit.com/products/3008) to allow you to plug wires in, or you could solder wires directly to the extender.

In terms of the combo, the prop shield does not have holes for the inner pins (Vusb, Aref, A10, A11), so I would mount the prop shield on the bottom, the FrankB PCB and Teensy in the middle, and the feather adapter on top. At the moment, I'm thinking of using the extra long male pins (https://www.adafruit.com/products/400) for the Prop shield + Teensy, and mounting the feather adapter with female headers underneath, so it can be removable. But, I'll probably change my mind 10 times before actually doing the soldering.

Remember to heed the comments in the feather adapter, and not connect the Vbattery pin on the back.

[michaelmeissner]

I forgot to mention where you can order the PCB from: https://pcbs.io/user/FrankB.

It was something like 3-4 weeks from order to delivery, and you get 4 boards for $2.80 (this is delivery to the USA).

[michaelmeissner]

I finally wired up my prop shield, feather adapter, FrankB adapter to get at the bottom pins, and Teensy 3.2. I soldered everything together directly. However the bottom pins are a little short to fit in a standard stacking header, and my soldering job could be better.

Any way, step 1 was to solder the long pins to the Teensy, which on the 14 pin rows, I had just enough of the pin sticking through the Teensy to solder on the top (you need to solder it on the top so that the FrankB shield will fit underneath directly. I had the feather and prop shields in place, to make sure I was soldering the pins to the right length.

Step 2 was to solder long pins for the back, taking out the pin for Vbattery. Note, the pins are moved up so when you attach the prop shield they just protrude under the prop shield, and using diagonal cutters to trim the pins down.

Step 3 was to solder normal male headers to the 4 inside pins, using a 5 pin header, and taking out one pin, since Vusb is 0.2" from Aref, A10, and A11.

Step 4 was to solder a wire to the reset pad under the Teensy, so that I can reset it without having to go into programming mode.

Step 5 was to solder the FrankB adapter underneath the Teensy. I should have made sure that all of the pins were connected before going to the next stages, but I didn't, and one of the pins does not seem to be connected.

Step 6 is to solder small female headers into the 2x7 pins brought out by the FrankB adapter. I had to go over these headers with a rotary tool to make sure all of the edges were sanded down, so the stacking headers on the feather adapter could be mounted.

Step 7 is to solder a small protoboard on the left side, that I will eventually use to bring out Vbattery, A10, A11, reset, program, etc. into a area with female or male headers.

Here are two pictures after step 7:



Step 8 is to solder the Feather adapter underneath the Teensy, FrankB shield, and protoboard.

Step 9 is to solder the stacking headers to the feather adapter so that feather wings can be added. Before soldering, I put the headers into the feather board, and used a sharpie to indicate where to cut the pins, and I cut the pins with diagonal cutters, so the stacking header pins did not protrude too much under the feather adapter. I put in an already soldered feather wing into the stacking header, so that the headers were positioned correctly.


Step 10 is to solder the 4 pin right angle headers to the prop shield to bring out the speaker pins on one side, and the LED pins on the other.

Step 11 is to solder the prop shield underneath the Feather board.

Step 12 is to make sure everything works. I used the OLED feather wing. As was discussed in viewtopic.php?f=57&t=100042, the OLED adapter has some problems with Teensys. At times, I would lower the Teensy's speed to 48Mhz instead of 96Mhz w/overclock, so that the OLED would work (usually after I got it running at 48Mhz, I could raise the speed back to 96Mhz).