Would it be possible to define an array of DigitalOut pins?

Topic last updated 11 Jun 2012, by user Daniel Dai. 5 replies tag array, Digital I/O
user Daniel Dai
11 Jun 2012

Hi, All,

I am wrting a programe to control a group of stepper motors and each motor requires 4 wires (CLK, ENaBle, DIRection, FULlstep).

Now I havev to define the DigitalOut pins as follows:

DigitalOut clk1(p21);
DigitalOut enb1(p23);
DigitalOut dir1(p25); / / 0 clockwise, 1 anti-clockwise
DigitalOut ful1(p27);

DigitalOut clk2(p22);
DigitalOut enb2(p24);
DigitalOut dir2(p26); / / 0 clockwise, 1 anti-clockwise
DigitalOut ful3(p28);

In the program, I have to repeat the samilar codes several times.

I wonder if it is allowed to define an array of DigitalOut, something like

DigitalOut clk[2](p21,p22);
DigitalOut enb[2](p23, p24);

Thus I can reuse the codes by access the I/O pins by index, rather by the name. e.g. clk[0] will be p21, clk[1] will be p22.

However, compiling the codes above reports errors:

'A value of type "PinName" cannot be used to initilize an entity of type mbed::DigitalOut[2]'

Is there any construction function of DigitalOut to get this job done? Any comments are apprecaited indeed.

Dan

Replies

user Daniel Dai
11 Jun 2012

Find a way walk around. Using an array of pointer.

// variable definition
DigitalOut clk1[p21];
DigitalOut clk2[p22];
DigitalOut *p[2];

In the programme,

main()
{ ...
// initialized the pointers
p[0]=&clk1;
p[1]=&clk2;
....
// access to clk1, 2 .... n, and reverse it
for (i=0;i<n;i++)
    *p[i]=!(*p[i]);
...

}

I see it is a bit odd, but it works. Please let me know if you have any better and clear solution.

user Wim van der Vegt
11 Jun 2012

Hi,

In my code i'm using a simple static array like (no pointers required):

    DigitalOut Do[6] = {
        DigitalOut(p11),    //DO1   - Lower Cylinder
        DigitalOut(p12),    //DO2   - Upper Cylinder
        DigitalOut(p13),    //DO3   - Slack
        DigitalOut(p14),    //DO4   - Lower Clamp
        DigitalOut(p15),    //DO5   - Upper Clamp
        DigitalOut(p16)     //DO6   - Seal Pressure
    };
    int Dos = (sizeof(Do) / sizeof(Do[0])) - 1;

    for (int i=0; i<Dos; i++) {
        Do[i]=1;
    }

wvd_vegt

user Daniel Dai
11 Jun 2012

user Wim van der Vegt wrote:

Hi,

In my code i'm using a simple static array like (no pointers required):

    DigitalOut Do[6] = {
        DigitalOut(p11),    //DO1   - Lower Cylinder
        DigitalOut(p12),    //DO2   - Upper Cylinder
        DigitalOut(p13),    //DO3   - Slack
        DigitalOut(p14),    //DO4   - Lower Clamp
        DigitalOut(p15),    //DO5   - Upper Clamp
        DigitalOut(p16)     //DO6   - Seal Pressure
    };
...

wvd_vegt

Appreciated. That's much better and clever.

user Igor Skochinsky
11 Jun 2012

You don't even have to call the constructors explicitly. The following should work as well:

DigitalOut Do[6] = {
        p11,    //DO1   - Lower Cylinder
        p12,    //DO2   - Upper Cylinder
        p13,    //DO3   - Slack
        p14,    //DO4   - Lower Clamp
        p15,    //DO5   - Upper Clamp
        p16     //DO6   - Seal Pressure
    };
user Daniel Dai
11 Jun 2012

user Igor Skochinsky wrote:

You don't even have to call the constructors explicitly. 

DigitalOut Do[6] = {
        p11,    //DO1   - Lower Cylinder
     ...
        p16     //DO6   - Seal Pressure
    };

What is the difference between using

DigitalOut p11;

and

DigitalOut(p11);

and

DigitalOut varName(p11);

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