Several have asked the question if a Teensy 3.5 will work with our BITeensio board for this application.? The answer is NO because, as far as we have been able to determine, USB "Host" mode only works on the Teensy 3.6.?
When they had the Teensy 3.5 manufactured, PJRC seems to have left some components off it so USB host mode couldn't be implemented though the traces appear to be on the board.? I don't know if those components could be added (you'd have to be pretty good with a very fine soldering iron and know what the components were) or if that would even make it work.? There might be some internal programming for the ARM processor as well that would have to be updated and I can't answer those questions.
When we designed the BITeensio to replace the Raduino and our own RadI2Cino cards we settled on the Teensy 3.6 as it was a good bit superior in speed and capability to the Teensy 3.5.? The only minor disadvantage is the 3.6 is NOT 5 volt compliant on any of its I/O like some of the I/O pins on the Teensy 3.5.? We didn't see this as a disadvantage though as most of the later crop of useful items run on 3.3V anyway and our color displays require 3.3V only.? This, plus the smaller footprint of the Teensy series made the Teensy 3.6? a much better choice as the BITeensio's MPU.?
The Teensy 3.6's on board 3.3V regulator has sufficient current handling capability to run the smaller 2.8" Color screen/back light, the 3.3V I2C bus, the Si5351a and the TSX0102 level shifter for the BITeensio's 5V I2C bus and still have some reserve.? Also, the Teensy 3.5 was not enough cheaper than the 3.6 to warrant using it so again, the answer is NO, the Teensy 3.5 will not work with the BITeensio card in any of our applications.
Jim Sheldon, W0EB
TSW Project Coordinator
Jim Sheldon