Support for SW PWM and third motor

include/a4988.h

@@ -4,6 +4,9 @@
 #define CFG_SAMPLE_RATE_US      5
 #define CFG_PERIPHERAL_SRC_PCM  1
 #define CFG_DEPRECATED_ARG      0
+#define PI_PWM_0		12
+#define PI_PWM_1		13
+#define PI_SW_PWM_RANGE		255
 
 #include <queue>
 #include <string>
@@ -75,6 +78,7 @@ namespace simon {
         std::queue<std::shared_ptr<c_cmd>> m_queue;
         unsigned m_pwm_freq;
         bool m_alive;
+	bool m_hw_pwm_possible;
       private:
         void initialize(void);
         int set_pwm_freq(const unsigned pwm_freq);

src/drivers/a4988.cpp

@@ -5,11 +5,17 @@
 #include <thread>
 #include <string>
 #include <memory>
+#include <algorithm>
+#include <iterator>
 
 #include <iostream>
 
 namespace simon {
   namespace a4988 {
+  // Anonymous namespace
+  namespace {
+  	
+  }
   c_allegro_4988::c_allegro_4988(std::unique_ptr<a4988_settings_t> ptr_set)
     : m_ptr_set(std::move(ptr_set)), m_initialized(false), m_alive(true)
   {
@@ -30,11 +36,22 @@ namespace simon {
           if (!set_pwm_freq(std::round(1e6/move->period_us))) {
             // TODO: proper error handling
           }
-          gpioHardwarePWM(m_ptr_set->gpio_step, m_pwm_freq, PI_HW_PWM_RANGE/2);
-          gpioWrite(m_ptr_set->gpio_dir, move->dir);
+	  if (m_hw_pwm_possible) {
+            gpioHardwarePWM(m_ptr_set->gpio_step, m_pwm_freq, PI_HW_PWM_RANGE/2);
+	  }
+	  else {
+            gpioSetPWMfrequency(m_ptr_set->gpio_step, m_pwm_freq);
+	    gpioPWM(m_ptr_set->gpio_step, PI_SW_PWM_RANGE/2);	    
+	  }
+	  gpioWrite(m_ptr_set->gpio_dir, move->dir);
           auto t_sleep = move->period_us*move->steps;
           std::this_thread::sleep_for(std::chrono::microseconds(t_sleep));
-          gpioHardwarePWM(m_ptr_set->gpio_step, m_pwm_freq, 0);
+	  if (m_hw_pwm_possible) {
+	    gpioHardwarePWM(m_ptr_set->gpio_step, m_pwm_freq, 0);
+	  }
+	  else {
+	    gpioPWM(m_ptr_set->gpio_step, 0);
+	  }
         }
         else if (*cmd == "enable") {
           auto enable = std::static_pointer_cast<c_enable>(cmd);
@@ -83,7 +100,11 @@ namespace simon {
     gpioWrite(m_ptr_set->gpio_dir, 0);
     // Set PWM to 0
     m_pwm_freq = 1000;
-    gpioHardwarePWM(m_ptr_set->gpio_step, m_pwm_freq, 0);
+    unsigned pwms[] = {PI_PWM_0, PI_PWM_1};
+    bool m_hw_pwm_possible = std::find(std::begin(pwms), std::end(pwms), m_ptr_set->gpio_step) != std::end(pwms);
+    if (m_hw_pwm_possible) {
+    	gpioHardwarePWM(m_ptr_set->gpio_step, m_pwm_freq, 0);
+    }
     m_initialized = true;
   }
   int c_allegro_4988::enable(void)