Programming the Teensy3.1

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fische007

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So have a Special question in programming a Teensy3.1 via another Teensy3.1

I have a System where 4 Teensy3.1 are working together. Now I want to connect only one Teensy3.1 to my PC und want to program all the Teensy devices via this first device.

The Teensy3.1 decices are connetd through I2C Interface.

When I look at the schematic of the Teensy3.1 ist seems, that program is coming through USB in, going through the K20 MCU and Exits via the I2C Interface (K20 works as a Bridge). This I2C Interface is connected to the Mini54 which than is connected to the program Pins of the K20.

My idea is now to program directly via the I2C and not via USB.

Anybody any idea on this and how to program one Teensy via another??
 
But what is the Situation:

the K20 MCU is programed via the mini54 MCU. This you can see in the schematic Diagramm. The Input to the Mini54 comes via the I2C of the K20 MCU. Therefor I have the theorie, that the K20 MCU is in program mode a Bridge from USB to I2C.

Anybody here who knows how the programing really happens?
 
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Programming is done via the JTAG interface. The I2C is not used, they may be connected, but I've not seen any activity on it.

When trying to debug my Derivative version of the Teensy, I had to probe these lines as well as the other 4 Jtag lines. Only the Jtag line had any activity on it when the Mini54 was put into programming mode.

What I believe the Mini54 does is load a Memory only Bootloader into the K20 to then let it program its Flash in it's entirety. It then goes dorment. It's very unlikely you will be able to use the Teensyloader to load the other Teensy's via the I2C bus, without some modifications to the Bootloader, and that is Closed source.

However, if you can forgo the need to use the Teensyloader and only use it to initially program your own bootloader on each of the other chips, then you can (with a some work) create a I2C bootloader that can flash the remote K20's. Have a look at this http://forum.pjrc.com/threads/24385-Flash-Teensy-3-0-from-sd-card?highlight=Flash thread to give you insight into how to do it. You'll have to adapt the SD part to being I2C.
 
johnnyfp

yes your theory could be true. The idea to install an own bootloader seams very interesting. I'll try it. Thanks a lot for the hint.
 
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