Teensy 2.0 alternatives, ATmega32U4

User avatar
solarnz

07 Jan 2014, 10:34

Are you planning on using a board per hand, or one board for both?

If you're planning on using two boards, the Pro Micro should be enough.

I would not recommend the Nano, as it does not use an AtMega32u4 chipset. The Pro Micro does, which means that software that is designed to run on the Teensy 2.0 board can run on it. You will have to look up the Arduino Leonardo / Micro / Pro Micro pin out to map the pin names between what the teensy uses and the Arduino uses, but that is it.

The Pro Micro does indeed not have a reset button, however this is not required.
1) With the default bootloader, it will stay in programming mode for 10 seconds (I think) when it is plugged in before booting the firmware that has been loaded.
2) You can wire your own switch on to it, all you have to do is connect the RESET pin to ground.

An added benefit of the Teensy and it's HalfKay bootloader is that it doesn't spend 10 seconds once it is plugged in to allow for programming. You have to explicitly either press the reset button, or short the reset pin to ground to allow you to program it. This could potentially save you a lot of frustration when trying to use your keyboard in your bios - Imagine being unable to hit the setup key due to your keyboard still booting!

User avatar
Soarer

25 Jan 2014, 15:55

Pro Micro pinout with non-Arduino-weeny names...
pro_micro_pinout.png
pro_micro_pinout.png (343.29 KiB) Viewed 5493 times

False_Dmitry_II

11 Mar 2014, 18:46

So just how important is the extra ram of the teensy++ 2.0 when considering changeable function layers?

Because I just spent technically more on the teensy++ 2.0 itself than the M0116 it's going to be driving, and I want two separate press, not hold, button layer changes. One for F-keys, and the other for inverse-T arrows on numpad and other such keys there. I haven't found anything talking about what, specifically, the ram cost is - just someone's post when his wasn't working because he went over available ram.

These mostly seem to have the same specs/chip as the regular teensy 2, even the ones which have as many pins as the teensy++ 2.0, which includes the same ram.

User avatar
clickclack123

12 Mar 2014, 05:50

False_Dmitry_II wrote:So just how important is the extra ram of the teensy++ 2.0 when considering changeable function layers?

Because I just spent technically more on the teensy++ 2.0 itself than the M0116 it's going to be driving, and I want two separate press, not hold, button layer changes. One for F-keys, and the other for inverse-T arrows on numpad and other such keys there. I haven't found anything talking about what, specifically, the ram cost is - just someone's post when his wasn't working because he went over available ram.

These mostly seem to have the same specs/chip as the regular teensy 2, even the ones which have as many pins as the teensy++ 2.0, which includes the same ram.
Using TMK firmware for my ergodox, I've used layouts with 12 layers without any problems and have about 8k left over. A teensy++ has 4x the ram of the teensy in an ergodox. How many layers do you want to use?!!

The extra ram is not important IMO as the teensy has enough ram for any reasonable number of layers.

False_Dmitry_II

12 Mar 2014, 19:20

clickclack123 wrote:
False_Dmitry_II wrote:So just how important is the extra ram of the teensy++ 2.0 when considering changeable function layers?

Because I just spent technically more on the teensy++ 2.0 itself than the M0116 it's going to be driving, and I want two separate press, not hold, button layer changes. One for F-keys, and the other for inverse-T arrows on numpad and other such keys there. I haven't found anything talking about what, specifically, the ram cost is - just someone's post when his wasn't working because he went over available ram.

These mostly seem to have the same specs/chip as the regular teensy 2, even the ones which have as many pins as the teensy++ 2.0, which includes the same ram.
Using TMK firmware for my ergodox, I've used layouts with 12 layers without any problems and have about 8k left over. A teensy++ has 4x the ram of the teensy in an ergodox. How many layers do you want to use?!!

The extra ram is not important IMO as the teensy has enough ram for any reasonable number of layers.
Certainly not that much. Probably not even as much as you've done. I think what I'll do then is set it up in some way that it is removable, and buy something else to run it if I do another project that needs more pins or whatnot.

User avatar
lowpoly

13 Mar 2014, 14:23

clickclack123 wrote:Using TMK firmware for my ergodox, I've used layouts with 12 layers without any problems
What do you do with 12 layers? Can you actually memorize that and not forget it?

As for Teensy alternatives:

Image

http://www.hobbytronics.co.uk/atmega32u ... o-breakout

Comes with Arduino bootloader pre-installed.

User avatar
matt3o
-[°_°]-

13 Mar 2014, 14:41

lowpoly wrote: As for Teensy alternatives:

Image

http://www.hobbytronics.co.uk/atmega32u ... o-breakout

Comes with Arduino bootloader pre-installed.
this is interesting. how do you connect to the USB? I see a D+/- is that it?

User avatar
lowpoly

13 Mar 2014, 14:53

Where do you see that? Should be pins 3 + 4.

User avatar
matt3o
-[°_°]-

13 Mar 2014, 15:03

Image

User avatar
lowpoly

13 Mar 2014, 15:12

Lol, I was looking really hard at the other pic, and the pcb ... :oops:

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matt3o
-[°_°]-

13 Mar 2014, 15:32

I think I'll take a bunch of these

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Muirium
µ

13 Mar 2014, 15:37

I thought you were thinking smaller…

http://www.pjrc.com/store/ic_atmega32u4_tqfp.html

User avatar
matt3o
-[°_°]-

13 Mar 2014, 16:08

The Breakout Board above is flat enough without USB port or other components. I believe you can put it between the PCB and the plate just under the spacebar. No need of SMD madness.

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Muirium
µ

13 Mar 2014, 16:10

Ah, well, if it fits there!

How large would the space bar have to be? I have ambitions for my 4.0 unit ones from Round 5. Of course, there is always the underside of the PCB to resort to. (At the back of a stepped case!)

User avatar
lowpoly

13 Mar 2014, 16:15

Size is 56.6x20.9x2.7mm.

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matt3o
-[°_°]-

13 Mar 2014, 16:18

wow, 56mm is way too much.

I'll try with a teensy3 then.

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Muirium
µ

13 Mar 2014, 16:19

Indeed. That's too wide to fit between the switch and stabs of a 6.25u space bar, even. A Teensy 2 is about 30 mm on the long axis.

Oh, and I have a Teensy 3.1 now, so good to hear it!

User avatar
matt3o
-[°_°]-

13 Mar 2014, 16:23

the advantage of teensy 3 is that it's also shorter on the Y axis. I have 5mm between the PCB and the plate, the teensy 3 seems like 4/4.5mm. It should fit.

edit: doublechecked. It turned out that I have 5 - 1.5mm. So the teensy3 wouldn't fit anyway unless I cut a hole in the plate. Anyway the teensy 3 is flat enough

JBert

13 Mar 2014, 16:59

matt3o wrote:The Breakout Board above is flat enough without USB port or other components. I believe you can put it between the PCB and the plate just under the spacebar. No need of SMD madness.
But what about those empty component holes on the breakout board? Those look through-hole solder points for a clock crystal and some extra capacitors related to it. Won't that be thicker than SMD components?

EDIT: Ok, refused already by its excessive width.

User avatar
lowpoly

13 Mar 2014, 17:20

JBert wrote:But what about those empty component holes on the breakout board? Those look through-hole solder points for a clock crystal and some extra capacitors related to it.
You can also connect these parts to the side pins (should be 16/17).

User avatar
lowpoly

14 Mar 2014, 16:00


User avatar
philpirj

28 May 2014, 01:57

$12.75
Pololu A-Star 32U4 Micro
Image

http://www.pololu.com/product/3101

All 15 (pins) can be used as digital I/O and 8 can be used as analog inputs. An extra 3 digital I/O lines are accessible through the ISP header.
Less pins than Teensy 2.0, 18 vs 25.

However 18 pins should be sufficient for 6*12 = 72 keys, or 8 * 10 = 80 keys, making this one a good candidate for diy 60% keyboards.

User avatar
matt3o
-[°_°]-

28 May 2014, 09:48

this is very lovely indeed. you need some creative matrix design, but still feasible.

as always... where the hell do I get them in EU?

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scottc

28 May 2014, 10:49

"comes preloaded with an Arduino-compatible bootloader"

Hopefully we can replace it!

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matt3o
-[°_°]-

28 May 2014, 11:04

also wondering why nobody gives direct access to the USB pins...

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Muirium
µ

28 May 2014, 12:49

Putting USB's 4 pins right on the edge, along with the rest, would be a huge improvement for these guys. And the reset pin! So we can access everything while mounted on a PCB or just hand wired.

User avatar
alinh

16 Jul 2014, 12:25

I can confirm that Pro Micro works great with Soarer and tmk.

I bought this guy :

Leonardo Pro Micro ATmega32U4 Arduino IDE 1.0.3 Bootloader replace Pro Mini

with free shipping; It arrived in 7 days .

Took a while to figure out how to upload stuff (RST + GND twice puts it in boot mode for 8 seconds).

I used avrdude on linux :

Code: Select all

avrdude -p m32u4 -P /dev/ttyACM0 -c avr109 -U flash:w:firmware/Soarer_at2usb_v1.12_atmega32u4.hex
Soarer's pin mapping is a big help :ugeek:

I'm a noob at this so no idea what pins should be avoided (if any), but for a Soarer converter or (in my case) a numpad it's great.. Did I mention it's 8.68e ?

Matt3o's guide on building the firmware was a big help also :geek:

User avatar
Muirium
µ

16 Jul 2014, 12:39

What's the startup time like in ordinary use? I've heard these use a bootloader which waits to check if you're grounding RST for some seconds on every USB start. Annoying for keyboard wake from sleepers like me!

User avatar
alinh

16 Jul 2014, 12:41

Muirium wrote: What's the startup time like in ordinary use? I've heard these use a bootloader which waits to check if you're grounding RST for some seconds on every USB start. Annoying for keyboard wake from sleepers like me!
Didn't time it, but feels about the same as teensy... Will check tonight when I get home.

arbitrarycombination

16 Jul 2014, 15:05

I’ve been using the SparkFun Pro Micro for a while, and I’m satisfied with it. Biggest plus to me is the Micro-USB connector, since I refuse to buy any more Mini-USB stuff (this is one of my pet peeves). It doesn’t have space for ISP pin headers though. More annoyingly, it does not have any mounting holes :(

The Arduino Pro Micro is nice as well. Has Micro-USB and ISP pin headers, but comes with the pin rows pre-soldered (at least mine did), so it’s hard to stuff in a keyboard case.

For anyone concerned with bootloader times: if you tinker with AVR processors regularly, I recommend getting an AVR Dragon for about 50€. This allows you to flash anything to a wide range of AVR processors via ISP or JTAG, without worrying about bootloader stuff. Highly recommended if you can justify the expense :)

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