Run mruby / c on PSoC 5

In this article, I will show you the procedure to run the α version of mruby / c with PSoC5 Prototyping Kit (CY8CKIT-059).

PSoC4 Prototyping Kit (CY8CKIT-049) can be used in the same procedure.

mruby / c is an implementation of mruby that requires less resources at runtime. It is assumed to operate at 64KB or less. Currently, the α version is being distributed.

For information on obtaining the mruby / c α version, see Mruby / c Initiatives of Shimane Software Development Center (ITOC). -Please see itoc.jp/news/10).

Things necessary

• CY8CKIT-059
• PSoC Creator --mruby / c α version --mruby OSS version (downloadable from mruby forum)

Overall flow

1. Create a simple C program project
2. Add mruby / c to 1 project
3. Compile the mruby program and embed it in 2.

Project creation

Create an empty project.

If "CY8CKIT-059" does not appear in "Target hardware", select "CY8C5888LTI-LP097" in "Target device".

In the case of PSoC4, it will be "CY8CKIT-049" or "CY8C4247AZI-M485".

On the next screen, select "Empty Schematic". Next, enter the project name and so on. Here, the project name is "mrubyc_sample".

Blink LED

Add Digital Output Pin to the schematic.

Double-click this Pin to set it.

--Set "Name" to "LED" --Uncheck "HW connection"

Set the pin

Open the .cydwr file and set the LED port to "P2 [1]".

In the case of PSoC4, the LED port is "P1 [6]".

Build

Build the project here.

By building, the code related to the LED output set earlier will be automatically generated.

Creating a C program

Create the main function of main.c as follows.

main function

int main()
{
    CyGlobalIntEnable; /* Enable global interrupts. */

    /* Place your initialization/startup code here (e.g. MyInst_Start()) */

    for(;;)
    {
        /* Place your application code here. */
        LED_Write(1);
        CyDelay(200);
        LED_Write(0);
        CyDelay(200);
    }
}

Run

Build and write to the board by selecting [Debug]-[Program]. It is OK if the LED on the board blinks.

Copy the mruby / c files

All the following files (xxx.c and xxx.h) in the src folder obtained by unzipping the mruby / c α version are copied to the PSoC Creator project folder (the folder containing main.c).

Add files to your project

Select [Project]-[Existing Item ...] to add the mruby / c α version file (xxx.c). You can select multiple files and add them at once.

Add method

Make the LED_Write function and CyDelay function used in the C program available from mruby. Add each method to the Object class.

Open the class.c file and add or modify the following.

Header file to add

#include "LED.h"
#include "CyLib.h"

Function to add

mrb_value c_led(struct VM *vm, mrb_value v)
{
  LED_Write( v.value.i );
  return v;
}

mrb_value c_delay(struct VM *vm, mrb_value v)
{
  CyDelay(v.value.i);
  return v;
}

mrb_init_class_Rewrite object function

static void mrb_init_class_object(void)
{
  // Class
  static_class_object = mrb_class_alloc("Object", -1);
  // Methods
  mrb_define_method(static_class_object, "led", c_led);
  mrb_define_method(static_class_object, "delay", c_delay);
}

The mrb_define_method function in the mrb_init_class_object function associates the C function with the mruby method.

Creating a mruby program

Create the following mruby program as sample.rb. The LED blinks at a different timing than the program created in C.

sample.rb

led 1
delay 100
led 0
delay 900

Compile with mrbc

Compile sample.rb with mruby (OSS version) to create sample.c. Copy sample.c to the same folder as main.c in the PSoC project.

  mrbc -E -Bary sample.rb 

Rewrite main.c and call the mruby program from C

Add the following to main.c.

Add header file

#include "vm.h" 
#include "load.h" 
#include "errorcode.h" 
#include "static.h" 
#include "sample.c"

Add the mrubyc function.

mrubyc function

int mrubyc(void)
{
  struct VM *vm;

  init_static();

  vm = vm_open();
  if( vm == 0 ){
    printf("VM open Error\n");
    return -1;
  }

  int ret = loca_mrb_array(vm, ary);
  if( ret != NO_ERROR ){
    printf("MRB Load Error (%04x_%04x)\n", ret>>16, ret&0xffff);
    return -1;
  }

  vm_boot( vm );

  int keep_execute = 1;
  while( keep_execute ){
    if( vm_run_step(vm) < 0 ){
      keep_execute = 0;
    }
  }

  vm_close( vm );

  return 0;
}

main function

int main()
{
    CyGlobalIntEnable; /* Enable global interrupts. */

    /* Place your initialization/startup code here (e.g. MyInst_Start()) */

    for(;;)
    {
        /* Place your application code here. */
        mrubyc();
    }
}

Build and run

Build and write to the board by selecting [Debug]-[Program]. It is OK if the LED on the board blinks.

It's been a little long explanation, but now you can run the mruby / c α version on PSoC5.