A class to access MCU registers

Back from holidays, back to other hobbies.

One thing that I hate when programming on MCUs is that you almost always access register directly through macros, masks and bit shifting operations; so, inspired by this talk on Youtube I decided to write my own code to access registers.

The result is a couple of templates that makes it possible to access registers in a clean way.

First is the Bitfield class: it allows to access some specific bits on a memory address; you can combine many Bitfields with an union. For example:

union SR1 {
        Bitfield<uint16_t, 0, 1> sb;
        Bitfield<uint16_t, 1, 1> addr;
        Bitfield<uint16_t, 2, 1> btf;
        Bitfield<uint16_t, 3, 1> add10;
        Bitfield<uint16_t, 4, 1> stopf;
        Bitfield<uint16_t, 6, 1> rxne;
        Bitfield<uint16_t, 7, 1> txne;
        Bitfield<uint16_t, 8, 1> berr;
        Bitfield<uint16_t, 9, 1> arlo;
        Bitfield<uint16_t, 10, 1> af;
        Bitfield<uint16_t, 11, 1> ovr;
        Bitfield<uint16_t, 12, 1> pec_err;
        Bitfield<uint16_t, 14, 1> timeout;
        Bitfield<uint16_t, 15, 1> smb_alert;
 SR1* const sr1;

With the BitfieldArray class you can access the bits of a register in an array-like manner:

using ODR=BitfieldArray<uint16_t, 0, 1, 1>;
ODR* const odr;
odr.set(3, 1);

This not only looks nice, but it also avoids possible errors in accessing a register bits. And it supports exceptions 😀

The code is on github.

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