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

Topic last updated 11 Jun 2012, by Daniel Dai. 5 replies
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

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.

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

Daniel Dai
11 Jun 2012

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.

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
    };
Daniel Dai
11 Jun 2012

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);