Added the algorithm to go down stairs.

Added the necessary changes in the dynamixel interface to execute it.

include/darwin_registers.h

@@ -643,8 +643,8 @@ typedef enum {
                                                    //                                               |  detected  |  enable    
   DARWIN_GRIPPER_CNTRL                   = 0x0251, //    bit 7    |     bit 6    |    bit 5    |     bit 4    |    bit 3   |    bit 2   |    bit 1    |   bit 0
                                                    // left opened | right opened | left moving | right moving | close left | open left  | close right | open right 
-  DARWIN_STAIRS_CNTRL                    = 0x0252  // bit 7 | bit 6 | bit 5 | bit 4 |   bit 3  | bit 2 |     bit 1    |    bit 0
-                                                   //          current phase        | climbing |       | stop stairs  | start stairs
+  DARWIN_STAIRS_CNTRL                    = 0x0252  // bit 7 | bit 6 | bit 5 | bit 4 |   bit 3  |     bit 2    |        bit 1      |    bit 0
+                                                   //          current phase        | climbing | stop stairs  | start stairs down | start stairs up
 }darwin_registers;
 
 #define      GPIO_BASE_ADDRESS       0x0100
@@ -753,8 +753,9 @@ typedef enum {
 #define      STAIRS_MEM_LENGTH       1
 #define      STAIRS_EEPROM_ADDRESS   0x0066
 #define      STAIRS_EEPROM_LENGTH    30
-#define      STAIRS_START            0x01
-#define      STAIRS_STOP             0x02
+#define      STAIRS_START_UP         0x01
+#define      STAIRS_START_DOWN       0x02
+#define      STAIRS_STOP             0x04
 #define      STAIRS_STATUS           0x08
 #define      STAIRS_PHASE            0xF0
 

include/stairs.h

@@ -12,7 +12,7 @@ extern "C" {
 void stairs_init(uint16_t period_us);
 inline void stairs_set_period(uint16_t period_us);
 inline uint16_t stairs_get_period(void);
-void stairs_start(void);
+void stairs_start(uint8_t up);
 void stairs_stop(void);
 uint8_t is_climbing_stairs(void);
 uint8_t stairs_get_phase(void);