How do you generate a 40kHZ sine wave using teensy 4.1 that outputs to an analog pin? What is the max amplitude the sin wave could possibly produce? What are the options for this? Is there any example code?
Let's first make sure you are not confusing analogRead-pins and/or PWM-pins with what you seem to want to do. (Digital-To-Analog conversion)
- On the Teensy 4.1 the pins named A0.. A17 are analogRead-pins. (they use either one of the chips Analog-to-Digital-Convertors (ADC) )
- The pins labeled with PWM are able to simulate an analog voltage by rapidly switching the pin's fixed output voltage (3.3V) on and off.
You will need to use a low-pass filter to get a reasonably smooth analog output voltage.
The chips used in the Teensy 3.1 and 3.2 have a 12 bit hardware DAC (Digital-to-Analog-Convertor) which is available on pin A14.
The hardware DAC makes it MUCH easier to create relatively high frequency sinewaves.
The hardware DAC is NOT available on the Teensy 4.0 and 4.1.
There is always the option to use external DAC's. Both parallel DAC's and SPI DAC's are available. It also depends on how many samples per full wave you want (temporal resolution of your sinewave)
Finally, the max amplitude of the sinewave directly from the Teensy is always going to be the V-out of the pins, 3.3V
If that is not enough you may want to use an external opamp.
Some of the external DAC's can produce an output that is directly linked to the supply voltage you connect them to.
(That is, they have internal amplifiers ... The DAC receives digital setpoint from the Teensy at 3.3V levels, but creates an output voltage that depends on the V-supply to the DAC chip)
Sorry if it does not fully answer your question.