A library for the AX-12+ servo using external ICs instead of the SerialHalf-Duplex class

A library based on the AX-12+ library but using external hardware to convert from full to half duplex as suggested in the AX-12 datasheet. The buffers and NOT gate need to connected as shown below.

640

Don't forget the pull-up resistor!

Files at this revision

API Documentation at this revision

Comitter:
ms523
Date:
Sat Aug 06 12:20:27 2011 +0000
Child:
1:1dd9cd18975d
Commit message:
Initial revision

Changed in this revision

AX12.cpp Show annotated file Show diff for this revision Revisions of this file
AX12.h Show annotated file Show diff for this revision Revisions of this file
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/AX12.cpp	Sat Aug 06 12:20:27 2011 +0000
@@ -0,0 +1,472 @@
+/* mbed AX-12+ Servo Library
+ *
+ * Copyright (c) 2010, cstyles (http://mbed.org)
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#include "AX12.h"
+#include "mbed.h"
+
+AX12::AX12(PinName tx, PinName rx, PinName dir, int ID)
+        : _ax12(tx,rx), _dir(dir) {
+
+    _ax12.baud(1000000);
+    _ID = ID;
+    _dir = TRANSMIT; 
+    
+}
+
+// return 1 is the servo is still in flight
+int AX12::isMoving(void) {
+
+    char data[1];
+    read(_ID,AX12_REG_MOVING,1,data);
+    return(data[0]);
+}
+
+// Set continuous rotation speed from -1 to 1
+int AX12::SetCRSpeed(float speed) {
+
+    // bit 10     = direction, 0 = CCW, 1=CW
+    // bits 9-0   = Speed
+    char data[2];
+
+    int goal = (0x3ff * abs(speed));
+
+    // Set direction CW if we have a negative speed
+    if (speed < 0) {
+        goal |= (0x1 << 10);
+    }
+
+    data[0] = goal & 0xff; // bottom 8 bits
+    data[1] = goal >> 8;   // top 8 bits
+
+    // write the packet, return the error code
+    int rVal = write(_ID, 0x20, 2, data);
+
+    return(rVal);
+}
+
+// Set the mode of the servo
+//  0 = Positional (0-300 degrees)
+//  1 = Rotational -1 to 1 speed
+int AX12::SetMode(int mode) {
+
+    if (mode == 1) { // set CR
+        SetCWLimit(0);
+        SetCCWLimit(0);
+        SetCRSpeed(0.0);
+    } else {
+        SetCWLimit(0);
+        SetCCWLimit(300);
+        SetCRSpeed(0.0);
+    }
+    return(0);
+}
+
+float AX12::GetTemp (void) {
+
+    if (AX12_DEBUG) {
+        printf("\nGetTemp(%d)",_ID);
+    }
+    char data[1];
+    int ErrorCode = read(_ID, AX12_REG_TEMP, 1, data);
+    float temp = data[0];
+    return(temp);
+}
+
+float AX12::GetVolts (void) {
+    if (AX12_DEBUG) {
+        printf("\nGetVolts(%d)",_ID);
+    }
+    char data[1];
+    int ErrorCode = read(_ID, AX12_REG_VOLTS, 1, data);
+    float volts = data[0]/10.0;
+    return(volts);
+}
+
+void AX12::trigger(void) {
+
+    char TxBuf[16];
+    char sum = 0;
+
+    if (AX12_TRIGGER_DEBUG) {
+        printf("\nTriggered\n");
+    }
+
+    // Build the TxPacket first in RAM, then we'll send in one go
+    if (AX12_TRIGGER_DEBUG) {
+        printf("\nTrigger Packet\n  Header : 0xFF, 0xFF\n");
+    }
+
+    TxBuf[0] = 0xFF;
+    TxBuf[1] = 0xFF;
+
+    // ID - Broadcast
+    TxBuf[2] = 0xFE;
+    sum += TxBuf[2];
+
+    if (AX12_TRIGGER_DEBUG) {
+        printf("  ID : %d\n",TxBuf[2]);
+    }
+
+    // Length
+    TxBuf[3] = 0x02;
+    sum += TxBuf[3];
+    if (AX12_TRIGGER_DEBUG) {
+        printf("  Length %d\n",TxBuf[3]);
+    }
+
+    // Instruction - ACTION
+    TxBuf[4] = 0x04;
+    sum += TxBuf[4];
+    if (AX12_TRIGGER_DEBUG) {
+        printf("  Instruction 0x%X\n",TxBuf[5]);
+    }
+
+    // Checksum
+    TxBuf[5] = 0xFF - sum;
+    if (AX12_TRIGGER_DEBUG) {
+        printf("  Checksum 0x%X\n",TxBuf[5]);
+    }
+
+    // Transmit the packet in one burst with no pausing
+    for (int i = 0; i < 6 ; i++) {
+        _ax12.putc(TxBuf[i]);
+    }
+    
+    // This is a broadcast packet, so there will be no reply
+
+    return;
+}
+
+int AX12::SetGoal(int degrees, int flags) {
+
+// if flag[0] is set, were blocking
+// if flag[1] is set, we're registering
+// they are mutually exclusive operations
+
+    char reg_flag = 0;
+
+    char data[2];
+
+    // set the flag is only the register bit is set in the flag
+    if (flags == 0x2) {
+        reg_flag = 1;
+    }
+
+    // 1023 / 300 * degrees
+    short goal = (1023 * degrees) / 300;
+    if (AX12_DEBUG) {
+        printf("SetGoal to 0x%x\n",goal);
+    }
+
+    data[0] = goal & 0xff; // bottom 8 bits
+    data[1] = goal >> 8;   // top 8 bits
+
+    // write the packet, return the error code
+    int rVal = write(_ID, AX12_REG_GOAL_POSITION, 2, data, reg_flag);
+
+    if (flags == 1) {
+        // block until it comes to a halt
+        while (isMoving()) {}
+    }
+
+    return(rVal);
+
+}
+
+float AX12::GetPosition(void) {
+
+    if (AX12_DEBUG) {
+        printf("\nGetPosition(%d)",_ID);
+    }
+
+    char data[2];
+
+    int ErrorCode = read(_ID, AX12_REG_POSITION, 2, data);
+    short position = data[0] + (data[1] << 8);
+    float angle = (position * 300)/1024;
+
+    return (angle);
+}
+
+int AX12::SetCWLimit (int degrees) {
+
+    char data[2];
+
+    // 1023 / 300 * degrees
+    short limit = (1023 * degrees) / 300;
+
+    if (AX12_DEBUG) {
+        printf("SetCWLimit to 0x%x\n",limit);
+    }
+
+    data[0] = limit & 0xff; // bottom 8 bits
+    data[1] = limit >> 8;   // top 8 bits
+
+    // write the packet, return the error code
+    return (write(_ID, AX12_REG_CW_LIMIT, 2, data));
+
+}
+
+int AX12::SetCCWLimit (int degrees) {
+
+    char data[2];
+
+    // 1023 / 300 * degrees
+    short limit = (1023 * degrees) / 300;
+
+    if (AX12_DEBUG) {
+        printf("SetCCWLimit to 0x%x\n",limit);
+    }
+
+    data[0] = limit & 0xff; // bottom 8 bits
+    data[1] = limit >> 8;   // top 8 bits
+
+    // write the packet, return the error code
+    return (write(_ID, AX12_REG_CCW_LIMIT, 2, data));
+}
+
+int AX12::SetID (int CurrentID, int NewID) {
+
+    char data[1];
+    data[0] = NewID;
+    if (AX12_DEBUG) {
+        printf("Setting ID from 0x%x to 0x%x\n",CurrentID,NewID);
+    }
+    return (write(CurrentID, AX12_REG_ID, 1, data));
+
+}
+
+
+int AX12::read(int ID, int start, int bytes, char* data) {
+
+    char PacketLength = 0x4;
+    char TxBuf[16];
+    char sum = 0;
+    char Status[16];
+
+    Status[4] = 0xFE; // return code
+
+    if (AX12_READ_DEBUG) {
+        printf("\nread(%d,0x%x,%d,data)\n",ID,start,bytes);
+    }
+
+    // Build the TxPacket first in RAM, then we'll send in one go
+    if (AX12_READ_DEBUG) {
+        printf("\nInstruction Packet\n  Header : 0xFF, 0xFF\n");
+    }
+
+    TxBuf[0] = 0xff;
+    TxBuf[1] = 0xff;
+
+    // ID
+    TxBuf[2] = ID;
+    sum += TxBuf[2];
+    if (AX12_READ_DEBUG) {
+        printf("  ID : %d\n",TxBuf[2]);
+    }
+
+    // Packet Length
+    TxBuf[3] = PacketLength;    // Length = 4 ; 2 + 1 (start) = 1 (bytes)
+    sum += TxBuf[3];            // Accululate the packet sum
+    if (AX12_READ_DEBUG) {
+        printf("  Length : 0x%x\n",TxBuf[3]);
+    }
+
+    // Instruction - Read
+    TxBuf[4] = 0x2;
+    sum += TxBuf[4];
+    if (AX12_READ_DEBUG) {
+        printf("  Instruction : 0x%x\n",TxBuf[4]);
+    }
+
+    // Start Address
+    TxBuf[5] = start;
+    sum += TxBuf[5];
+    if (AX12_READ_DEBUG) {
+        printf("  Start Address : 0x%x\n",TxBuf[5]);
+    }
+
+    // Bytes to read
+    TxBuf[6] = bytes;
+    sum += TxBuf[6];
+    if (AX12_READ_DEBUG) {
+        printf("  No bytes : 0x%x\n",TxBuf[6]);
+    }
+
+    // Checksum
+    TxBuf[7] = 0xFF - sum;
+    if (AX12_READ_DEBUG) {
+        printf("  Checksum : 0x%x\n",TxBuf[7]);
+    }
+
+    // Transmit the packet in one burst with no pausing
+    _dir = TRANSMIT;     // switch to transmit...
+    for (int i = 0; i<8 ; i++) {
+        _ax12.putc(TxBuf[i]);
+    }
+    
+    // Wait for the bytes to be transmitted
+    wait (0.00004);
+    _dir = RECEIVE;     // switch back to receive...
+
+    // Skip if the read was to the broadcast address
+    if (_ID != 0xFE) {
+
+        // Receive the Status packet 6+ number of bytes read
+        for (int i=0; i<(6+bytes) ; i++) {
+            Status[i] = _ax12.getc();
+        }
+
+        // Copy the data from Status into data for return
+        for (int i=0; i < Status[3]-2 ; i++) {
+            data[i] = Status[5+i];
+        }
+
+        if (AX12_READ_DEBUG) {
+            printf("\nStatus Packet\n");
+            printf("  Header : 0x%x\n",Status[0]);
+            printf("  Header : 0x%x\n",Status[1]);
+            printf("  ID : 0x%x\n",Status[2]);
+            printf("  Length : 0x%x\n",Status[3]);
+            printf("  Error Code : 0x%x\n",Status[4]);
+
+            for (int i=0; i < Status[3]-2 ; i++) {
+                printf("  Data : 0x%x\n",Status[5+i]);
+            }
+
+            printf("  Checksum : 0x%x\n",Status[5+(Status[3]-2)]);
+        }
+
+    } // if (ID!=0xFE)
+
+    return(Status[4]);
+}
+
+int AX12:: write(int ID, int start, int bytes, char* data, int flag) {
+
+// number of bytes in packet
+// 0xff, 0xff, ID, Length, Intruction(write), Address, Param(s), Checksum
+// 7 + bytes
+
+    char TxBuf[16];
+    char sum = 0;
+    char Status[6];
+
+    if (AX12_WRITE_DEBUG) {
+        printf("\nwrite(%d,0x%x,%d,data,%d)\n",ID,start,bytes,flag);
+    }
+
+    // Build the TxPacket first in RAM, then we'll send in one go
+    if (AX12_WRITE_DEBUG) {
+        printf("\nInstruction Packet\n  Header : 0xFF, 0xFF\n");
+    }
+
+    TxBuf[0] = 0xff;
+    TxBuf[1] = 0xff;
+
+    // ID
+    TxBuf[2] = ID;
+    sum += TxBuf[2];
+
+    if (AX12_WRITE_DEBUG) {
+        printf("  ID : %d\n\r",TxBuf[2]);
+    }
+
+    // packet Length
+    TxBuf[3] = 3+bytes;
+    sum += TxBuf[3];
+
+    if (AX12_WRITE_DEBUG) {
+        printf("  Length : %d\n\r",TxBuf[3]);
+    }
+
+    // Instruction
+    if (flag == 1) {
+        TxBuf[4]=0x04;
+        sum += TxBuf[4];
+    } else {
+        TxBuf[4]=0x03;
+        sum += TxBuf[4];
+    }
+
+    if (AX12_WRITE_DEBUG) {
+        printf("  Instruction : 0x%x\n\r",TxBuf[4]);
+    }
+
+    // Start Address
+    TxBuf[5] = start;
+    sum += TxBuf[5];
+    if (AX12_WRITE_DEBUG) {
+        printf("  Start : 0x%x\n\r",TxBuf[5]);
+    }
+
+    // data
+    for (char i=0; i<bytes ; i++) {
+        TxBuf[6+i] = data[i];
+        sum += TxBuf[6+i];
+        if (AX12_WRITE_DEBUG) {
+            printf("  Data : 0x%x\n\r",TxBuf[6+i]);
+        }
+    }
+
+    // checksum
+    TxBuf[6+bytes] = 0xFF - sum;
+    if (AX12_WRITE_DEBUG) {
+        printf("  Checksum : 0x%x\n\r",TxBuf[6+bytes]);
+    }
+
+    // Transmit the packet in one burst with no pausing
+    _dir = TRANSMIT;    // switch to transmit...
+    for (int i = 0; i < (7 + bytes) ; i++) {
+        _ax12.putc(TxBuf[i]);
+    }  
+
+    // Wait for data to transmit
+    wait (0.00004);
+    _dir = RECEIVE;     // switch back to receive...
+
+    // make sure we have a valid return
+    Status[4]=0x00;
+
+    // we'll only get a reply if it was not broadcast
+    if (_ID!=0xFE) {
+
+        // response is always 6 bytes
+        // 0xFF, 0xFF, ID, Length Error, Param(s) Checksum
+        for (int i=0; i < 6 ; i++) {
+            Status[i] = _ax12.getc();
+        }
+
+        // Build the TxPacket first in RAM, then we'll send in one go
+        if (AX12_WRITE_DEBUG) {
+            printf("\nStatus Packet\n  Header : 0x%X, 0x%X\n\r",Status[0],Status[1]);
+            printf("  ID : %d\n\r",Status[2]);
+            printf("  Length : %d\n\r",Status[3]);
+            printf("  Error : 0x%x\n\r",Status[4]);
+            printf("  Checksum : 0x%x\n\r",Status[5]);
+        }
+
+
+    }
+
+    return(Status[4]); // return error code
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/AX12.h	Sat Aug 06 12:20:27 2011 +0000
@@ -0,0 +1,105 @@
+/* mbed AX-12+ Servo Library
+ *
+ * Copyright (c) 2010, cstyles (http://mbed.org)
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef MBED_AX12_H
+#define MBED_AX12_H
+
+#include "mbed.h"
+
+#define AX12_WRITE_DEBUG 0
+#define AX12_READ_DEBUG 0
+#define AX12_TRIGGER_DEBUG 0
+#define AX12_DEBUG 0
+
+#define AX12_REG_ID 0x3
+#define AX12_REG_CW_LIMIT 0x06
+#define AX12_REG_CCW_LIMIT 0x08
+#define AX12_REG_GOAL_POSITION 0x1E
+#define AX12_REG_MOVING_SPEED 0x20
+#define AX12_REG_VOLTS 0x2A
+#define AX12_REG_TEMP 0x2B
+#define AX12_REG_MOVING 0x2E
+#define AX12_REG_POSITION 0x24
+
+#define AX12_MODE_POSITION  0
+#define AX12_MODE_ROTATION  1
+
+#define AX12_CW 1
+#define AX12_CCW 0
+
+#define TRANSMIT 1
+#define RECEIVE 0
+
+class AX12 {
+
+public:
+
+    // define which pins are used, and the ID of this instance
+    // Mutiple AX12's can share the same pins.
+    AX12(PinName tx, PinName rx, PinName dir, int ID);
+
+    // methods for writing and reading registers
+    int read(int ID, int start, int length, char* data);
+    int write(int ID, int start, int length, char* data, int flag=0);
+
+    // set goal angle in integer degrees
+    // flags[0] = blocking (only returns when goal reached
+    // flags[1] = register. Requires broadcast trigger to activate
+    int SetGoal(int degrees, int flags = 0);
+
+    // Mode = 0, positional
+    // Mode = 1, continuous rotation
+    int SetMode(int mode);
+
+    // Speed is -1.0 (CCW) to 1.0 (CW)
+    int SetCRSpeed(float speed);
+
+    // set these in degrees, CCW limit is 300
+    // If both are set to zero, we are continuous rotation
+    int SetCWLimit(int degrees);
+    int SetCCWLimit(int degrees);
+
+    // Change the ID
+    int SetID(int CurrentID, int NewID);
+
+    // returns true if the motor is in motion
+    int isMoving(void);
+
+    // broadcast to trigger registered goals
+    void trigger(void);
+
+    // Get current angle, only valid 0-300
+    float GetPosition();
+
+    // In volts and ^C
+    float GetTemp(void);
+    float GetVolts(void);
+
+private :
+    Serial _ax12;
+    DigitalOut _dir;
+    int _ID;
+
+};
+
+#endif