Library documentation (particularly for Teensy 4.0)

MichaelMeissner

Senior Member+
As I answer questions about the library, I notice some of the library pages have not been updated for Teensy 4.0. A meta question is whether it is time to make a separate Teensy 1.0/2.0/2.0++ library page to cut down on the clutter for the majority of current Teensy users.

Main library page. It could use a Teensy 4.0 column. Whether Teensy 3.2, 3.5, and 3.6 need to be split into separate columns, I dunno. And of course the meta issue about Teensy 2.x only libraries and the 2.x column:

Serial UART page. In addition to adding a Teeny 4.0 column (and possibly removing Teensy 1.0/2.0/2.0++), I think there should be a row added for each UART that mentions if there is hardware FIFO support, and if there is support, what size FIFO is used. Another question is whether the Teensy 4.0 supports hardware flow control at all.

SPI page. This page mentions SPI4teensy, which added Teensy 3.5/3.6 support 2 years ago, but the Github page has not been modified in 2 years. The page uses SS, but the pinout sheet uses CS. Obviously the page should mention the other SPI buses on the Teensy 3.5, 3.6, and 4.0, and for the 3.5/3.6 alternate pins. It may be useful to document the 'fast' CS pins in each of the Teensys and possibly what DMA characteristics are available. It probably would be a good idea to link to the better SPI design page in this document. I think it would be useful to maintain a list of the display devices here that have Teensy acceleration:

I2C page. This page would be simplified by splitting off the Teensy 1.0/2.0/2.0+ 5v stuff from the 3.x/4.0 3.3v stuff. This page should probably mention using 2.2K pull-up resistors for the 3.3v systems instead of 4.7K. And this page should mention all of the I2C buses support on a given platform. It probably should list that the improved I2C library does not yet have Teensy 4.0 support:

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It would also be useful until all of the T3 libraries have been ported, to have a list of which libraries do not yet work for T4 but the library has not been ported yet (but is planned), or whether the library can't be ported to T4.

Also the question has come up on what to do about seemingly dead libraries that were imported from elsewhere, but the maintainer has moved on (or died) and is no longer updating the library.
 
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I tend to agree that situation becomes very confusing.
My suggestion for a clean way forward is that Teensyduino ONLY provides the core functionality and PJRC maintains only a list of links to libraries that Paul and/or a small number of forum members have verified to work with T2,3,4. If SW is not maintained or found not supported anymore by actual TD version, it should be removed from list. If there is a second zip file with all libraries Paul maintains would help but should not be part of TD.
 
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