LED Matrix expansion module

Has anyone written code to drive the LEDs on the LED Matrix expansion module?

Comments

  • Livermore, CA (50 miles SE of San Francisco)
  • Here are some demos for the LED Matrix board, written in Spin, BASIC, and C. I think I may have posted earlier versions of them a long time ago, but I can't remember.
  • Thanks!
  • ersmith wrote: »
    Here are some demos for the LED Matrix board, written in Spin, BASIC, and C. I think I may have posted earlier versions of them a long time ago, but I can't remember.
    Sorry for being critical but I see that the C code just calls the Spin object. Are we going to start seeing all low-level driver code written in Spin and called from C? I guess I'd prefer to see the driver code in C with a Spin interface if required.

  • David Betz wrote: »
    ersmith wrote: »
    Here are some demos for the LED Matrix board, written in Spin, BASIC, and C. I think I may have posted earlier versions of them a long time ago, but I can't remember.
    Sorry for being critical but I see that the C code just calls the Spin object. Are we going to start seeing all low-level driver code written in Spin and called from C? I guess I'd prefer to see the driver code in C with a Spin interface if required.

    Sure, driver code can be written in C, or it can be written in Spin. The point is not to write it twice -- I already had some Spin code for the matrix, so I just used it in C rather than having to re-write it. If you really want a C only version you can convert it with spin2cpp :). But you can also do it the other way around, Spin code can call C (at least within the fastspin framework).

    So if you're writing a driver from scratch pick whatever language you prefer or already have code for. Some of the (fastspin) Spin library routines are written in C, and vice-versa.
  • evanhevanh Posts: 8,073
    edited 2019-11-08 - 23:49:16
    A lot of spin2 sources is just pasm2. So not really spin code. Not that I've looked at this example.

    EDIT: Looking at it now ... it's quite handy for learning the interface between C and spin.
    "We suspect that ALMA will allow us to observe this rare form of CO in many other discs.
    By doing that, we can more accurately measure their mass, and determine whether
    scientists have systematically been underestimating how much matter they contain."
  • ersmith wrote: »
    David Betz wrote: »
    ersmith wrote: »
    Here are some demos for the LED Matrix board, written in Spin, BASIC, and C. I think I may have posted earlier versions of them a long time ago, but I can't remember.
    Sorry for being critical but I see that the C code just calls the Spin object. Are we going to start seeing all low-level driver code written in Spin and called from C? I guess I'd prefer to see the driver code in C with a Spin interface if required.

    Sure, driver code can be written in C, or it can be written in Spin. The point is not to write it twice -- I already had some Spin code for the matrix, so I just used it in C rather than having to re-write it. If you really want a C only version you can convert it with spin2cpp :). But you can also do it the other way around, Spin code can call C (at least within the fastspin framework).

    So if you're writing a driver from scratch pick whatever language you prefer or already have code for. Some of the (fastspin) Spin library routines are written in C, and vice-versa.
    Sure, I know I can write in whatever language I want. I guess I'm just hoping that the vast majority of user written drivers won't be only in Spin with a C interface. I think one of the main ways new people learn a new processor is by looking at example code and if most of the example code is in a language they don't understand it may be a barrier. It's not so much that *I* can't read Spin. I can. I just wonder if it's a good idea for potential customers looking through the P2 version of OBEX.

  • Eric: I notice that your C wrapper for your led_matrix_demo uses the Spin object as if it were a C++ class instance. Do you support class definitions in your C compiler?
  • David Betz wrote: »
    Sure, I know I can write in whatever language I want. I guess I'm just hoping that the vast majority of user written drivers won't be only in Spin with a C interface. I think one of the main ways new people learn a new processor is by looking at example code and if most of the example code is in a language they don't understand it may be a barrier. It's not so much that *I* can't read Spin. I can. I just wonder if it's a good idea for potential customers looking through the P2 version of OBEX.

    Ah, I see. That's a good point, availability of good C examples is important, and I agree with you that it would be nice to see some C drivers.

    Unfortunately unless Parallax gets behind something it's hard to see how anything other than Spin will gain traction. At the moment Chip's Spin interpreter is the only "official" development tool announced (although it isn't available yet). I hope Chip will provide some way to call C code from his interpreter, that would make it feasible to write portable drivers in C. Otherwise Spin drivers will be the de facto standard, since they'll be the most portable (we can call Spin from C, but not vice-versa).
  • David Betz wrote: »
    Eric: I notice that your C wrapper for your led_matrix_demo uses the Spin object as if it were a C++ class instance. Do you support class definitions in your C compiler?

    Very limited class declarations, with the functions "inline" in the struct, like:
    #include <stdio.h>
    
    struct point {
        int x, y;
        void offset(int a, int b) {
            x += a; y += b;
        }
        int getx() { return x; }
        int gety() { return y; }
    } p;
    
    int main() {
        p.x = 1;
        p.y = 2;
        p.offset(10, 100);
        printf("p=(%d, %d)\n", p.getx(), p.gety());
    }
    
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