Teensy 3.2 USB Microcontroller Development Board

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1

Hi,

I was reading through the datasheet and specs for the Teensy 3.2 USB Microcontroller Development Board, and had a couple quick questions.

  1. What is the maximum sampling rate if using 4 analog input channels?
  2. What is the maximum sampling rate if using 6 analog input channels?
  3. What bit resolution can be expected for each of the above cases?

Thank you.

2

Hi,

Here are answers to your questions:

The best way to answer this questions is to first establish the maximum sampling rate of the ADC interface itself. Then, sampling multiple channels will simply be a division of that sampling rate.
See this answer from the creator of Teensy concerning the maximum sampling rate. In another, more recent post, he mentions “It can actually run at 400 kHz or higher”. With proper hardware setup (taking care of stray capacitance and other electrical issues of your analog signal to the ADC pin), you may achieve even higher rates.

According to the datasheet, typical settling time is 15 µs (30 µs worst case), which gives us sampling rates of ~66.67 kHz (~33.33 kHz) if you want to wait for all 12 bits of the ADC to settles properly. If you do not mind having a bit less accuracy (lets say ~10 bits), you can sample a bit faster.

So, for a quick calculation assuming you need full 12-bit accuracy from the ADC and you are running non-stop sampling against 6 channels, your theoretical sampling rates will be:
Total sampling rate: ~33.33 kHz (worst case)
Sampling rate per channel: ~5.55 kHz.

Since this would create a lot of interrupts if handled by the CPU directly, we strongly recommend you use DMA to handle the ADC samples.

We hope this helps.

Sincerely,

P.-S.: For more details about various aspects of the Teensy boards and its programming, we recommend you check this super useful post!