• ATSAML21 DAC BAD DESIGN

    Carlos Reverbel • 02/02/2018 at 20:19 • 0 comments

    Just found-out about a really bad design of the SAML21 micro. In order to use it's DAC as an internal reference for the internal OpAmps I must output the DAC to it's IO pin (pin 3, in the case of DAC0). The problem is that pin 3 is shared with OpAmp0 negative input. It is then impossible to use the DAC0 AND the negative input of OpAmp0 at the same time...

    So I won't be able to implement the following current source circuit with this micro.

    For version 2 I will probably change the microcontroller...

  • Blank PCBs arrived from OSH Park

    Carlos Reverbel • 01/15/2018 at 17:20 • 0 comments

    - Boards just arrived from OSH Park. Still waiting the components to arrive...

  • First test on the microcontroller

    Carlos Reverbel • 01/05/2018 at 16:03 • 0 comments

    Proof of concept...

    • Fortunately I had a 64-TQFP breakout board for testing the microcontroller and developing the software while the main board is in production.
    • I was forced to use the 64-pin version of this micro (ATSAML21J) because I was planning to use all the 3 internal OpAmps of this chip (which are all accessible only on the 64-pin version).
      • For the final version I plan to find a way to use the 32-pin version to save cost and space.

  • PCB Design - REV 1

    Carlos Reverbel • 01/05/2018 at 15:47 • 0 comments

    Proof of concept - Hardware

    • Designed a 4 layer PCB prototype and sent to OSH Park for fabrication.
      • For a 2 layer PCB I must change the coin cell holder.