Porting a project from 3.6 to 4.1: what should I look out for?

[Nantonos]

I'm about to resurrect a project I started on 3 or 4 years ago and abandoned (health issues, other priorities) a couple of years ago. Meanwhile, supply-chain issues mean that the original target, Teensy 3.6, seems unavailable so I am changing to 4.1 (no ethernet needed).

I'm aware of some pin assignment differences, which seem easy to accommodate. The power draw from Teensy 4.1 worries me a bit, though I hope to drop the clock down to mitigate that. The memory layout seems a bit more complicated but also seems to be mainly handled automatically by the compiler. I see that the onboard ADC has a lower ENOB but I think that 10 bit will be fine in this application. Anything else I should be aware of?

In case it helps, the project will include:

1. Two SPI 18-bit DACs (AD5781ARUZ) and a Vref (MAX6226_50)
2. Two 14-bit octal SPI DACS (DAC8168C, with 74AHCT125 for level shifting)
3. FreqMeasure and FreqCount (different pins, now)
4. A few RGB LEDs
5. A small screen plus encoder and some buttons. I2C, because it is mainly for setup and calibration
6. Four pots connected to onboard ADC
7. USB Host

[PaulStoffregen]

Welcome back Nantonos! Good to see you again.

If you're using the ordinary SPI library and analogRead(), odds are pretty good it will "just work".

You could set Tools > CPU Speed for 396 or 150 MHz to get lower power.

[Nantonos]

Hi Paul! Yes, I planned to use the ordinary SPI library, with transactions.