[driver] Adding AS5047 driver and example

[hshose]

• driver
• example
• tested on hardware

[salkinium]

Nice, just some nitpicks.

[salkinium]

This is the modm namespace which is quite generic. Would be good to move to struct as5047 or put into the relevant :math module.

[hshose]

I'm not sure, how to move it into the struct?

If I declare `setMsbToEvenParity` as `static constexpr` in the `as5047` struct, I get an error saying `error: 'static constexpr uint16_t modm::as5047::setMsbToEvenParity(uint16_t)' used before its definition`

struct as5047
{
	enum class Errorfl : uint16_t
	{
		Parerr = Bit2,
		Invcomm = Bit1,
		Frerr = Bit0,
	};
	MODM_FLAGS16(Errorfl)

	enum class Prog : uint16_t
	{
		Progver = Bit6,
		Progotp = Bit3,
		Otpref = Bit2,
		Progen = Bit0,
	};
	MODM_FLAGS16(Prog)

	enum class Diaagc : uint16_t
	{
		Magl = Bit11,
		Magh = Bit10,
		Cof = Bit9,
		Lf = Bit8,
	};
	MODM_FLAGS16(Diaagc)

	static constexpr uint16_t
	setMsbToEvenParity(const uint16_t num)
	{
		uint16_t par = 0x7fff & num;
		par ^= par >> 8;
		par ^= par >> 4;
		par ^= par >> 2;
		par ^= par >> 1;
		return ((par & 1) << 15) | (0x7fff & num);
	}

	enum class Register : uint16_t
	{
		ReadNop = setMsbToEvenParity(((1 << 14) | 0x0000)),
		ReadErrfl = setMsbToEvenParity(((1 << 14) | 0x0001)),
		ReadProg = setMsbToEvenParity(((1 << 14) | 0x0003)),
		ReadDiaagc = setMsbToEvenParity(((1 << 14) | 0x3FFC)),
		ReadMag = setMsbToEvenParity(((1 << 14) | 0x3FFD)),
		ReadAngleunc = setMsbToEvenParity(((1 << 14) | 0x3FFE)),
		ReadAnglecom = setMsbToEvenParity(((1 << 14) | 0x3FFF)),

	};

	struct modm_packed Data
	{
		/// @return
		constexpr float
		getAngleRad() const
		{
			const uint16_t angle = data & 0x3fff;
			return static_cast<float>(angle) / 16383.f * 2.f * std::numbers::pi_v<float>;
		}

		/// @return
		constexpr float
		getAngleDeg() const
		{
			const uint16_t angle = data & 0x3fff;
			return static_cast<float>(angle) / 16383.f * 360.f;
		}

		/// @return
		constexpr uint16_t
		getAngleRaw() const
		{
			const uint16_t angle = data & 0x3fff;
			return angle;
		}

		uint16_t data;
	};
};  // struct as5047

I think this might be related to this:

The Standard should make clear that a constexpr member function cannot be used in a constant expression until its class is complete.

Do you have any suggestions?
Should I put everything into an as5047 namespace?

I don't think moving the function as is to the math: is appropriate, since the function specifically calculates and sets bit 15 of a uint16_t, if moved to math:, a more generic version might be more appropriate. Also, other modm modules like etlcpp have their own functions to calculate parity bits...

[salkinium]

Ugh, C++ amiright!1!!

You can put it into a modm::details namespace then and use /// @cond and /// @endcond to block doxypress from indexing it (Examples). Prolly prefix the function with as5047_ to avoid collisions if you wanna be super careful.

[hshose]

Ugh, C++ amiright!1!!

🐈 No we are super careful 🐱

[salkinium]

Thanks!