AP_HAL_Linux: RCOutput_Navio: allow to have other offset

libraries/AP_HAL_Linux/HAL_Linux_Class.cpp

@@ -94,7 +94,7 @@ static LinuxRCOutput_AioPRU rcoutDriver;
   use the PCA9685 based RCOutput driver on Navio
  */
 #elif CONFIG_HAL_BOARD_SUBTYPE == HAL_BOARD_SUBTYPE_LINUX_NAVIO
-static LinuxRCOutput_Navio rcoutDriver(RPI_GPIO_27);
+static LinuxRCOutput_Navio rcoutDriver(3, RPI_GPIO_27);
 #elif CONFIG_HAL_BOARD_SUBTYPE == HAL_BOARD_SUBTYPE_LINUX_ZYNQ
 static LinuxRCOutput_ZYNQ rcoutDriver;
 #elif CONFIG_HAL_BOARD_SUBTYPE == HAL_BOARD_SUBTYPE_LINUX_BEBOP

libraries/AP_HAL_Linux/RCOutput_Navio.cpp

@@ -50,11 +50,13 @@ using namespace Linux;
 
 static const AP_HAL::HAL& hal = AP_HAL_BOARD_DRIVER;
 
-LinuxRCOutput_Navio::LinuxRCOutput_Navio(uint8_t oe_pin_number) :
+LinuxRCOutput_Navio::LinuxRCOutput_Navio(uint8_t channel_offset,
+                                         uint8_t oe_pin_number) :
     _i2c_sem(NULL),
     _enable_pin(NULL),
     _frequency(50),
     _pulses_buffer(new uint16_t[PWM_CHAN_COUNT]),
+    _channel_offset(channel_offset),
     _oe_pin_number(oe_pin_number)
 {
 }
@@ -169,7 +171,7 @@ void LinuxRCOutput_Navio::write(uint8_t ch, uint16_t period_us)
 
     uint8_t data[2] = {length & 0xFF, length >> 8};
     uint8_t status = hal.i2c->writeRegisters(PCA9685_ADDRESS,
-                                             PCA9685_RA_LED0_OFF_L + 4 * (ch + 3),
+                                             PCA9685_RA_LED0_OFF_L + 4 * (ch + _channel_offset),
                                              2,
                                              data);
 

libraries/AP_HAL_Linux/RCOutput_Navio.h

@@ -6,7 +6,8 @@
 
 class Linux::LinuxRCOutput_Navio : public AP_HAL::RCOutput {
     public:
-    LinuxRCOutput_Navio(uint8_t oe_pin_number);
+    LinuxRCOutput_Navio(uint8_t channel_offset,
+                        uint8_t oe_pin_number);
     ~LinuxRCOutput_Navio();
     void     init(void* machtnichts);
     void     reset_all_channels();
@@ -27,6 +28,8 @@ private:
     uint16_t _frequency;
 
     uint16_t *_pulses_buffer;
+
+    uint8_t _channel_offset;
     uint8_t _oe_pin_number;
 };