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Thread: prototyping/software develpment on 3.6, running on a LC of 3.2

  1. #1

    prototyping/software develpment on 3.6, running on a LC of 3.2

    Hi

    Are there specific pitfalls with development on a teensy 3.6, while the target is a LC or 3.2?

    Off course the extra speed and extra features from the 3.6 are not usable.

    Alain

  2. #2
    Senior Member+ MichaelMeissner's Avatar
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    Cool

    I would suggest prototyping with the actual board you are going to use, rather that doing it in the big system, and trying to shoe horn things into the smaller system later. That way you discover things like running out of memory or depending on the speed of hardware floating point rather than much slower software emulation immediately, rather than after the fact. Typically this might mean having a LC, 3.2, 3.5, and 3.6 prototype boards, each with pin headers soldered in, and you replace the board in the breadboard with the board you are trying out.

    In addition to memory and speed, while Paul has striven to make the main pins on the Teenys be compatible with each other, it is not completely compatible. For example, which pins are touch pins, which pin has the DAC assigned to it, and which pins are PWM pins. I came up with this spreed sheet to remind myself of the differences between the different boards when doing pin layout:



    One thing to think about, is you probably want to limit EEPROM usage on the LC, as it doesn't have regular EEPROM (I believe it uses part of the flash memory for programs). If you use EEPOM in the middle of the loop to store information, the chip will wear out much faster. Using EEPROM to remember defaults when the system is booting is fine, just not writing to it very frequently. Also, the LC doesn't ahve a real time clock that can keep time across boots via a coin cell battery.

  3. #3
    Quote Originally Posted by MichaelMeissner View Post
    I would suggest prototyping with the actual board you are going to use, rather that doing it in the big system, and trying to shoe horn things into the smaller system later. That way you discover things like running out of memory or depending on the speed of hardware floating point rather than much slower software emulation immediately, rather than after the fact. Typically this might mean having a LC, 3.2, 3.5, and 3.6 prototype boards, each with pin headers soldered in, and you replace the board in the breadboard with the board you are trying out.

    In addition to memory and speed, while Paul has striven to make the main pins on the Teenys be compatible with each other, it is not completely compatible. For example, which pins are touch pins, which pin has the DAC assigned to it, and which pins are PWM pins. I came up with this spreed sheet to remind myself of the differences between the different boards when doing pin layout:



    One thing to think about, is you probably want to limit EEPROM usage on the LC, as it doesn't have regular EEPROM (I believe it uses part of the flash memory for programs). If you use EEPOM in the middle of the loop to store information, the chip will wear out much faster. Using EEPROM to remember defaults when the system is booting is fine, just not writing to it very frequently. Also, the LC doesn't ahve a real time clock that can keep time across boots via a coin cell battery.
    Thanks for the answer and the spread sheet.

  4. #4
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    Really basic check, make sure your code actually compiles if you change the board type to LC, and when it does note down the memory used numbers as you add more bits. Some of the extra features in the 3.6 mean it can do things in fewer commands, so be careful assuming code that ocupies X flash and Y RAM compiled for a 3.6 will do the same on an LC.

    And yes the EEPROM is emulated so needs to be handled with care, and your actual design needs to allow for the fact that the LC is less current capacity for any hardware being driven from the 3.3V pin.

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