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void pwmSetRange (unsigned int range)

{

  if ((wiringPiMode == WPI_MODE_PINS) || (wiringPiMode == WPI_MODE_PHYS) || (wiringPiMode == WPI_MODE_GPIO))

  {

    *(pwm + PWM0_RANGE) = range ; delayMicroseconds (10) ;

    *(pwm + PWM1_RANGE) = range ; delayMicroseconds (10) ;

  }

}

void pwmSetClock (int divisor)

{

  uint32_t pwm_control ;

  divisor &= 4095 ;

  if ((wiringPiMode == WPI_MODE_PINS) || (wiringPiMode == WPI_MODE_PHYS) || (wiringPiMode == WPI_MODE_GPIO))

  {

    if (wiringPiDebug)

      printf ("Setting to: %d. Current: 0x%08X\n", divisor, *(clk + PWMCLK_DIV)) ;

    pwm_control = *(pwm + PWM_CONTROL) ;                // preserve PWM_CONTROL

// We need to stop PWM prior to stopping PWM clock in MS mode otherwise BUSY

// stays high.

    *(pwm + PWM_CONTROL) = 0 ;                          // Stop PWM

// Stop PWM clock before changing divisor. The delay after this does need to

// this big (95uS occasionally fails, 100uS OK), it's almost as though the BUSY

// flag is not working properly in balanced mode. Without the delay when DIV is

// adjusted the clock sometimes switches to very slow, once slow further DIV

// adjustments do nothing and it's difficult to get out of this mode.

    *(clk + PWMCLK_CNTL) = BCM_PASSWORD | 0x01 ;        // Stop PWM Clock

      delayMicroseconds (110) ;                 // prevents clock going sloooow

    while ((*(clk + PWMCLK_CNTL) & 0x80) != 0)  // Wait for clock to be !BUSY

      delayMicroseconds (1) ;

    *(clk + PWMCLK_DIV)  = BCM_PASSWORD | (divisor << 12) ;

    *(clk + PWMCLK_CNTL) = BCM_PASSWORD | 0x11 ;        // Start PWM clock

    *(pwm + PWM_CONTROL) = pwm_control ;                // restore PWM_CONTROL

    if (wiringPiDebug)

      printf ("Set     to: %d. Now    : 0x%08X\n", divisor, *(clk + PWMCLK_DIV)) ;

  }

} 

$ gpio mode 1 pwm

$ gpio pwm-ms

$ gpio pwm 1 7

$ gpio pwm-bal 

$ gpio pwm 1 7

┌────────────────────┤ Raspberry Pi Software Configuration Tool (raspi-config) ├──────────────────────┐

│                                                                                                     │

│1 Expand Filesystem            Ensures that all of the SD card storage is available to the OS        │

│2 Change User Password         Change password for the default user (pi)                             │

│3 Boot Options                 Choose whether to boot into a desktop environment or the command line │

│4 Wait for Network at Boot     Choose whether to wait for network connection during boot             │

│5 Internationalisation Options Set up language and regional settings to match your location          │

│6 Enable Camera                Enable this Pi to work with the Raspberry Pi Camera                   │

│7 Add to Rastrack              Add this Pi to the online Raspberry Pi Map (Rastrack)                 │

│8 Overclock                    Configure overclocking for your Pi                                    │

│9 Advanced Options             Configure advanced settings                                           │

│0 About raspi-config           Information about this configuration tool                             │

│                                                                                                     │

│                                                                                                     │

│                        <Select>                                   <Finish>                          │

│                                                                                                     │

└─────────────────────────────────────────────────────────────────────────────────────────────────────┘

┌────────────────────┤ Raspberry Pi Software Configuration Tool (raspi-config) ├──────────────────────┐

│                                                                                                     │

│  A1 Overscan     You may need to configure overscan if black bars are present on display         ↑  │

│  A2 Hostname     Set the visible name for this Pi on a network                                   ▮  │

│  A3 Memory Split Change the amount of memory made available to the GPU                           ▒  │

│  A4 SSH          Enable/Disable remote command line access to your Pi using SSH                  ▒  │

│  A5 Device Tree  Enable/Disable the use of Device Tree                                           ▒  │

│  A6 SPI          Enable/Disable automatic loading of SPI kernel module (needed for e.g. PiFace)  ▒  │

│  A7 I2C          Enable/Disable automatic loading of I2C kernel module                           ▒  │

│  A8 Serial       Enable/Disable shell and kernel messages on the serial connection               ▒  │

│  A9 Audio        Force audio out through HDMI or 3.5mm jack                                      ▒  │

│  AA GL Driver    Enable/Disable experimental desktop GL driver                                   ↓  │

│                                                                                                     │

│                                                                                                     │

│                        <Select>                                   <Back>                            │

│                                                                                                     │

└─────────────────────────────────────────────────────────────────────────────────────────────────────┘