I’ve touted the Arduino Nano Every and the Arduino Nano 33 IoT as the two best buys in the Arduino lineup, and that they should be preferred when appropriate to the application. But why are these such good deals?
First, they are both in the “Nano” form factor. This smaller board is less expensive to produce. Also look at the back of the boards (the original Nano, actually an inexpensive clone here, is at the top):
There are only parts on one side of the Nano 33 IoT and Nano Every boards. This saves quite a bit of money on the manufacturing cost.
However there is another money saving feature. These boards use the clock oscillator within the microcontroller rather than using an external ceramic or crystal oscillator. This is probably the second most expensive component on the board, after the microcontroller itself.
But what do we lose by using the built-in oscillator? Frequency accuracy and stability! But how much accuracy do we need. It’s important if we have to create accurate timing (as in a UART for the serial port) or perform accurate measurements related to time. The oscillators have a maximum error of 4% which is “good enough” for most applications, but could cause errors if the UART is used to communicate between boards and one is off by +4% while the other is off by -4%
Note that communication via I2C or SPI won’t have any issues and that the accuracy of the ADC and DAC (including PWM analog output) are not affected by clock speed. While some care may be needed in applications involving critical timing, most applications, especially those of hobbyists to whom these boards are directed, should work just fine with these reduced cost boards. And don’t forget the added advantages of more memory and features than the Nano board they can replace.