Constantin
Well-known member
Ladies and Gentlemen,
I continue to be stuck in the Midwest thanks to airline mishaps and took the time to expand the Eagle libraries for the bootloader chips that PJRC is offering and / or will be offering in the future. Specifically, I added the 5x5mm QFN-33 package for the Minitan54, as well as attempted to figure out what Mr. Stoffregen did to bless the LC with a even smaller bootloader chip than the Minitan54 that is meant for the Teensy 3.0 as well as the Teensy 3.1.
However, seeing that there is no schematic yet (as of this writing) describing the connections between the bootloader and the MKL26Z MCU that makes up the LC, all I could do was study the posted images very carefully and try to deduce the connections. As best as I can tell, the fine folk at PJRC are programming the bootloader MCU at PJRC (great idea!) once the LC board has been assembled. Only then, can the bootloader commandeer and help program the LC MCU using the SWD protocol. (At least this is what I think happens. Caveat emptor, I am a Mechie.)
So the above image shows what I think the connections are on the Teensy LC bootloader chip. Before I post libraries, I would like Mr. Stoffregen to weigh in on whether the connections look correct (once a schematic is posted, I'm happy to do that also). Please note that PJRC does not plan to ship the bootloader chips for the Teensy LC series for a while yet (several months). I simply had some time and thought it would be a fun puzzle.
I also worked on creating a QFN-33 package for the Minitan54. I picked a QFN-33 package from the ON Semiconductor library and made the connections per the data on the MiniTan54 sales page. I wonder if someone could double-check my work re: the port assignments for the Minitan54 and the connections to the MK20DX MCU that powers the Teensy 3.x series. The official pin assignments can be found here.
If the pin assignments and designations seem to make sense, please let me know. I'll post the updated bootloader libraries at that point. Since the 4x4mm QFN package is very similar to the 5x5mm package (save for the exterior dimensions), adding that should be pretty simple once the pin assignments have been confirmed.
EDIT: Past drawings / symbols above for the LC bootloader reflect an error in Pauls originally-posted schematic for the LC that have since been corrected. Pin 10 is attached to the tactile PGM switch, not pin 11, as originally shown.
I continue to be stuck in the Midwest thanks to airline mishaps and took the time to expand the Eagle libraries for the bootloader chips that PJRC is offering and / or will be offering in the future. Specifically, I added the 5x5mm QFN-33 package for the Minitan54, as well as attempted to figure out what Mr. Stoffregen did to bless the LC with a even smaller bootloader chip than the Minitan54 that is meant for the Teensy 3.0 as well as the Teensy 3.1.
However, seeing that there is no schematic yet (as of this writing) describing the connections between the bootloader and the MKL26Z MCU that makes up the LC, all I could do was study the posted images very carefully and try to deduce the connections. As best as I can tell, the fine folk at PJRC are programming the bootloader MCU at PJRC (great idea!) once the LC board has been assembled. Only then, can the bootloader commandeer and help program the LC MCU using the SWD protocol. (At least this is what I think happens. Caveat emptor, I am a Mechie.)
So the above image shows what I think the connections are on the Teensy LC bootloader chip. Before I post libraries, I would like Mr. Stoffregen to weigh in on whether the connections look correct (once a schematic is posted, I'm happy to do that also). Please note that PJRC does not plan to ship the bootloader chips for the Teensy LC series for a while yet (several months). I simply had some time and thought it would be a fun puzzle.
I also worked on creating a QFN-33 package for the Minitan54. I picked a QFN-33 package from the ON Semiconductor library and made the connections per the data on the MiniTan54 sales page. I wonder if someone could double-check my work re: the port assignments for the Minitan54 and the connections to the MK20DX MCU that powers the Teensy 3.x series. The official pin assignments can be found here.
If the pin assignments and designations seem to make sense, please let me know. I'll post the updated bootloader libraries at that point. Since the 4x4mm QFN package is very similar to the 5x5mm package (save for the exterior dimensions), adding that should be pretty simple once the pin assignments have been confirmed.
EDIT: Past drawings / symbols above for the LC bootloader reflect an error in Pauls originally-posted schematic for the LC that have since been corrected. Pin 10 is attached to the tactile PGM switch, not pin 11, as originally shown.
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