User Manual

Pretty-Printing out registers

There's

a lot

of registers on the SAMD21, and you often are going through ASF or another framework to get to them.

So having a way to see exactly what's going on is handy. This library from drewfish will help a ton!

https://github.com/drewfish/arduino-ZeroRegs (https://adafru.it/Bet)

M4 Performance Options

As of version 1.4.0 of the

Adafruit SAMD Boards

package in the Arduino Boards Manager, some options are available

to wring extra performance out of M4-based devices. These are in the

Tools

menu.

All of these performance tweaks involve a degree of uncertainty. There’s

no guarantee

of improved performance in

any given project, and

some may even be detrimental,

failing to work in part or in whole. If you encounter trouble,

select the default performance settings and re-upload.

Here’s what you get and some issues you might encounter…

CPU Speed (overclocking)

This option lets you adjust the microcontroller core clock…the speed at which it processes instructions…beyond the

official datasheet specifications.

Manufacturers often rate speeds conservatively because such devices are marketed for harsh industrial

environments…if a system crashes, someone could lose a limb or worse. But most creative tasks are less critical and

operate in more comfortable settings, and we can push things a bit if we want more speed.

There is a small but nonzero chance of code locking up or failing to run entirely. If this happens, try dialing back the

speed by one notch and re-upload, see if it’s more stable.

Much more likely, some code or libraries may not play well with the nonstandard CPU speed. For example, currently

the NeoPixel library assumes a 120 MHz CPU speed and won’t issue the correct data at other settings (this will be

worked on). Other libraries may exhibit similar problems, usually anything that strictly depends on CPU timing…you

might encounter problems with audio- or servo-related code depending how it’s written. If you encounter such code

or libraries, set the CPU speed to the default 120 MHz and re-upload.

Optimize