As much as I like this approach especially for prototyping custom teensy projects which needs more pins: Do the changes since the initial idea in the first post, i.e. getting rid of the expensive extra hardware, not lead to a more or less direct Teensy 3.6 competitor?
There is a PJRC published reference board on OSH Park with BOM - linked from PJRC.com - it relies on the PJRC MKL02 bootloader. Buying that from PJRC is some compensation for using the design.
With that Bootloader MCU from PJRC as part of the design of this unit it does the same.
Putting Teensy in (or near?) the name is likely a trademark issue.
I've not seen any post, on or paperwork that may come with, the MKL02 bootloader that may or may not allow product attribution of the inclusion of the 'PJRC bootloader' in some fashion?
** not a lawyer - just an avid follower of the work PJRC presents.
Brian: Is there SD or Flash space on the bottom side at this point? And are those USB Host parts/pads on the PCB?
Yeah, I'll need to come up with a better name to avoid confusion.
There is nothing on the bottom at this point. Interesting idea to add SD. Flash would be nice, but it's expensive!
The USB host pads are not on board; however, the pins are available on the header - USB1 +/- and VBUS.
Flash: Only the pads like the audioshield.
SD: I hope without levelshifters? (you announced them for an other board).
Yeah, I'll need to come up with a better name to avoid confusion.
There is nothing on the bottom at this point. Interesting idea to add SD. Flash would be nice, but it's expensive!
The USB host pads are not on board; however, the pins are available on the header - USB1 +/- and VBUS.
Thanks, wasn't sure of the bottom features - even open pads like the Audio board for a common flash - of course minimal layer PCB makes it tough to find a signal safe free space. Oh and you should add a LiPo JST connector and a charger circuit { onehorse did one on his ladybug }
As far as host USB - wasn't sure what the open large pads were - looking again that would be by what must be the LDO and not the USB part PJRC has on the T_3.6?
The board is getting interesting Brian. There is only one thing that I see that may be a challenge. No mounting holes? Don't think there is enough edge room to slide it into a case or anything as a work around.
I'm working on debugging this hardware design. Two boards have been manufactured with the same symptoms:
1. The bootloader shows up correctly when plugged into USB
2. The teensy loader loads the program and reboots, like normal
3. The teensy then does not show up as a Serial device
4. Digital I/O (i.e. blink) doesn't work
5. The reset_b pin pulses continuously
6. I measured 3.2V at the output of the diode leading to VBat, so I think VBat is getting power and this also probably means that the MK66FX1M0 internal regulator is working (this board does not use an external regulator, rather relies on the MK66FX1M0 internal regulator to drop the 5V USB to 3.3V).
That's it for now. More debugging later.
Did your get the hardware debugged? I have done a similar design a bit more focused on an specific application but have not reduced to hardware yet. Though I'd take advantage of your excellent work! Thanks!
Not yet. I've had limited time to debug it and my current scope is pretty terrible. I may manufacture one soon with a slightly different crystal, see if that fixes the issues.