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Hardware
Matt Davison edited this page Mar 3, 2025
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- The included Teensy has a wire that connects pin 32 (a pad on the underside of the board) with pin 2.
- This is done because the second output of the quad i2s peripheral uses pin 32, which isn't on an actual pin.
- Doing this keeps the first quad i2s output line (pin 7) free to use with the Teensy audio board.
- DO not use pin 2 in your code - this should be kept as being set to an input to avoid driving the pin and causing a short circuit.
- The Teensy uses 3.3V digital logic levels whereas the MAX98389 uses 1.8V.
- The i2s signals go through a Texas Instruments TXS0108EPWR chip to convert to/form 1.8V and 3.3V.
- The i2c signals (SDA and SCL) each go through a FET transistor circuit for level shifting as these are open-drain signals.
- The Teensy, which generates the 3.3V supply, is powered over USB.
- The 1.8V supply is generated from the 3.3V supply and therefore also powered by USB.
- The MAX98389 requires two supplies - one for digital logic (1.8V) and one for powering the amplifier output (5-10V). This allows the amp to be configured via i2c without the external power supply.
The transducer has an M4 thread on the underside. The included screw that secures it to the 3D printed base can be removed and the transducer screwed into other hardware.
Adding objects or mountings to the top of the actuator is likely to change the resonant frequency, gain, and quality factor. This will mean that the parameters need retuning. See the MIDI Control wiki page for info on how to do this.