MRD Lab / MX12

Robotis Dynamixel MX-12W Servo Library

Dependents:   SpindleBot_1_5b Utilisatio_MX12_V4

/media/uploads/labmrd/mx12.jpg

This is my attempt to adapt Chris Styles's AX12 library to work with my Dynamixel MX12 servos. This library is still very much a work in progress, and it may have some/many errors in it, but hopefully I will keep improving it to bring it up to snuff.

Dynamixel aficionados should also check out This MX28 library for a completely separate library that provides very similar functionality, and I wish I had known it existed before I started my work...

minimal example

#include "mbed.h"
#include "MX12.h"

int main() {

  MX12 mymx12 (p9, p10, 1);           // ID=1

  while (1) {
      mymx12.Set_Goal_Position(0);    // go to 0 degrees
      wait (2.0);
      mymx12.Set_Goal_Position(300);  // go to 300 degrees
      wait (2.0);
  }
}

Diff: MX12.h

Revision:
5:4c118a827f11
Parent:
3:624d04c390b8
--- a/MX12.h	Thu Jan 29 22:24:13 2015 +0000
+++ b/MX12.h	Tue Feb 10 21:52:40 2015 +0000
@@ -68,17 +68,28 @@
 #define MX12_MODE_POSITION  0
 #define MX12_MODE_ROTATION  1
 
+// For now we don't have a both option, since no
+// one should use that anyways.
+enum MX12_Direction {
+    MX12_DIR_IN,
+    MX12_DIR_OUT,
+    MX12_DIR_NONE
+};
+
 #define MX12_CW 1
 #define MX12_CCW 0
 
 #define MX12_INSTRUCTION_HEADER 0xff
 
+#define MX12_ERROR_RETURN       255
+#define MX12_NORMAL_RETURN        1
+
 // The max delay should be 508us according to:
 // http://support.robotis.com/en/product/dynamixel/mx_series/mx-12w.htm#Actuator_Address_05
 // And a max character should be 833 us according to:
 // (1 byte) / (9600 (bits per second)) = 833 microseconds
 // So 1000 should be a decent value, because 9600 bps is for chumps.
-#define MAX_DELAY_BETWEEN_CHARCTERS_IN_US 500
+#define MAX_DELAY_BETWEEN_CHARCTERS_IN_US 1500
 
 #ifndef M_PI
     #define M_PI    3.14159265358979323846  /* pi */
@@ -119,9 +130,11 @@
      * @param pin rx pin 
      * @param int ID, the Bus ID of the servo 1-255 
      */
-    MX12(PinName tx, PinName rx, int ID, int baud_rate=1000000);
+    MX12(PinName tx, PinName rx, PinName tx_enable_pin, PinName rx_enable_pin, int ID, int baud_rate=1000000);
 
     void Init(void);
+    
+    void ChangeDir(MX12_Direction dir);
 
 /** clockwise Angle Limit @retval CW Angle Limit in Degrees */  float Get_CW_Angle_Limit(void){return 0.087891*read_short(MX12_REG_CW_ANGLE_LIMIT);}
 /** counterclockwise Angle Limit @retval CCW Angle Limit in Degrees */  float Get_CCW_Angle_Limit(void){return 0.087891*read_short(MX12_REG_CCW_ANGLE_LIMIT);}
@@ -289,10 +302,14 @@
     //// Variables
     Serial mx12_out;
     Serial mx12_in;
+    DigitalOut tx_enable;
+    DigitalOut rx_enable;
     DigitalOut profileOut;
     int _ID;
+    int _baud;
 
     //// Functions
+    int read_raw(char* Status, int bytes=0);
     int read(int ID, int start, int length, char* data);
     int write(int ID, int start, int length, char* data);