Object Oriented example for the Data Acquisition Board for Pi Pico

RE: Object Oriented example for the Data Acquisition Board for Pi Pico

Jan Cumps — Wed, 20 Dec 2023 11:24:45 GMT

Follow-up: [mention:ff4ffc78cae84182b8cac557a297596f:f7d226abd59f475c9d224a79e3f0ec07]

RE: Object Oriented example for the Data Acquisition Board for Pi Pico

shabaz — Mon, 18 Dec 2023 15:57:11 GMT

Hi Jan,

This is a pretty detailed example of using STL and it's all microcontroller-friendly. This is a superb article that I'm going to make use of, since I mostly stick with the few STL features I'm familiar with (e.g. vector, map, pair) and need to learn more of them. Also some very neat features used in the coding, e.g. enum class, I've not seen before.

Although the code here is useful for those using the ADS111x series of chips, it's a great resource for anyone to simply study the code and apply the techniques elsewhere.

RE: Object Oriented example for the Data Acquisition Board for Pi Pico

ggabe — Mon, 18 Dec 2023 15:34:39 GMT

What do you think of encapsulating the buffer into a new object? Along with the different ways of accessing/representing it.

RE: Object Oriented example for the Data Acquisition Board for Pi Pico

Jan Cumps — Mon, 18 Dec 2023 14:00:59 GMT

for type safe use of the enumerators with the Pico C api, I made these controlled type casters:

    // safe conversions, only available within the class implementation
    inline uint8_t operator()(addr a) const {return (uint8_t)a;}
    inline addr operator()(uint8_t a) const {
        assert(a >= (*this)(addr::A_0) && a < (*this)(addr::A_LAST)); // debug support
        return  (addr)a;
    }
    inline uint8_t operator()(reg r) const {return (uint8_t)r;}
    inline uint8_t operator()(data_rate dr) const {return (uint8_t)dr;}
    inline uint8_t operator()(gain g) const {return (uint8_t)g;}
    inline uint8_t operator()(channel c) const {return (uint8_t)c;}
    inline uint8_t operator()(diff d) const {return (uint8_t)d;}

In code, this removes the explicit typedefs in the implementation. A few examples:

from:

adc_confreg[1] |= ((uint8_t)dr << 5); // set the DR bits

to:

adc_confreg[1] |= ((*this)(dr) << 5); // set the DR bits

from:

i2c_write_blocking(i2c_port, (uint8_t)address, buf, 3, false);

to:

i2c_write_blocking(i2c_port, (*this)(address), buf, 3, false);

It doesn't cost more runtime or code space.

I explicitly declared them private. The developer isn't supposed to convert the strongly typed constants. But it's needed to translate into the lower leve Pico C SDK APIs.