Pi3

[SiobhanRamsey]

Will this run on Pi3?

[dmontenegro]

@SiobhanRamsey I'm trying to make it work in my Pi3 also but I don't know what I have to do extra to listen it in the radio. Its show in ps aux to be running but It doesnt work. Did you figure it out ?

[in-sympathy]

Cheers, guys, any progress on this one? Badly want to run it on my Pi3 :)
Merry Christmas btw :)

[d4m4s74]

This project is basically abandoned, no updates for 3 years.

[in-sympathy]

Too bad 😟

[DavidWhaleMEF]

The problem is that the C program directly accesses the GPIO memory, and on the Raspberry Pi 2 and Pi 3 they used a different broadcom processor which results in all the memory mapped addresses for the hardware peripherals changing. The method the code uses to access GPIO for example is deprecated (it reads at a specific base address in real memory, which is only valid on the original BCM2835 chip in the Raspberry Pi 1). The Pi 2 uses a BCM2836 and the Pi3 uses yet another different CPU chip.

The recommended way to get the base address of the GPIO peripheral is to read the various magic numbers coded inside the BCM chip firmware, which is mapped into the virtual file /proc/device-tree/soc/ranges

So, the code in this file....

https://github.com/Make-Magazine/PirateRadio/blob/master/pifm.c#L99

Should be modified to read the various magic numbers from the soc file and use those instead.

Here is an example C file where I do this in one of my drivers...

https://github.com/whaleygeek/pyenergenie/blob/master/src/energenie/drv/gpio_rpi.c#L54

void gpio_init()
{
   uint32_t peri_base = BCM2708_PERI_BASE; /* default if device tree not found */
   uint32_t gpio_base;
   FILE* fp;

   /* for RPi2, get peri-base from device tree */
   if ((fp = fopen("/proc/device-tree/soc/ranges", "rb")) != NULL)
   {
      unsigned char buf[4];

      fseek(fp, 4, SEEK_SET);
      if (fread(buf, 1, sizeof(buf), fp) == sizeof(buf))
      {
         peri_base = buf[0]<<24 | buf[1]<<16 | buf[2]<<8 | buf[3];
      }
      fclose(fp);
   }

   gpio_base = peri_base + GPIO_BASE_OFFSET;


   /* open /dev/mem */
   if ((mem_fd = open("/dev/mem", O_RDWR|O_SYNC) ) < 0) 
   {
      printf("can't open /dev/mem \n");
      exit(-1); //TODO return a result code
   }

   /* mmap GPIO */
   gpio_map = mmap(
      NULL,             //Any adddress in our space will do
      BLOCK_SIZE,       //Map length
      PROT_READ|PROT_WRITE,// Enable reading & writting to mapped memory
      MAP_SHARED,       //Shared with other processes
      mem_fd,           //File to map
      gpio_base         //Offset to GPIO peripheral
   );

   close(mem_fd); //No need to keep mem_fd open after mmap

   if (gpio_map == MAP_FAILED) 
   {
      printf("mmap error %d\n", (int)gpio_map);//errno also set!
      exit(-1); //TODO return a result code
   }

   // Always use volatile pointer!
   gpio = (volatile unsigned *)gpio_map;
}

[microbit-rosslowe]

@DavidWhaleMEF I don't really have a great understanding of this code, but something like this?

master...04rlowe:patch-1

[in-sympathy]

So does anybody have a working version of this pifm file either source or compiled one for RasPi 3? 😇