Wifi Webserver to control the Speed of a motor using PID

Dependencies:   4DGL-uLCD-SE PID QEI SDFileSystem mbed

Files at this revision

API Documentation at this revision

Comitter:
electromotivated
Date:
Wed Nov 25 02:11:34 2015 +0000
Child:
1:1490beafb4f7
Commit message:
Upload;

Changed in this revision

4DGL-uLCD-SE.lib Show annotated file Show diff for this revision Revisions of this file
PID.lib Show annotated file Show diff for this revision Revisions of this file
QEI.lib Show annotated file Show diff for this revision Revisions of this file
SDFileSystem.lib Show annotated file Show diff for this revision Revisions of this file
main.cpp Show annotated file Show diff for this revision Revisions of this file
mbed.bld Show annotated file Show diff for this revision Revisions of this file
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/4DGL-uLCD-SE.lib	Wed Nov 25 02:11:34 2015 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/4180_1/code/4DGL-uLCD-SE/#2cb1845d7681
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/PID.lib	Wed Nov 25 02:11:34 2015 +0000
@@ -0,0 +1,1 @@
+http://developer.mbed.org/users/electromotivated/code/PID/#4ed1f5bccac8
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/QEI.lib	Wed Nov 25 02:11:34 2015 +0000
@@ -0,0 +1,1 @@
+http://developer.mbed.org/users/electromotivated/code/QEI/#50aae578cb89
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SDFileSystem.lib	Wed Nov 25 02:11:34 2015 +0000
@@ -0,0 +1,1 @@
+http://developer.mbed.org/users/mbed_official/code/SDFileSystem/#7b35d1709458
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Wed Nov 25 02:11:34 2015 +0000
@@ -0,0 +1,544 @@
+/*
+    Uses the ESP8266 WiFi Chip to set up a WiFi Webserver used to control 
+    the speed of a motor using a PID controller. USE FIREFOX Web 
+    Browser
+
+    NOTES: 
+    1. Webpage Handling in this program is specific to a CUSTOM 
+    WEBPAGE. Program must be modified to handle specfically a new 
+    webpage. A copy of the webpage for this program can be found at 
+    the end of this program page. Simply copy and past text into a
+    html file and save as the given name.
+    
+    2. Developed and tested with FireFox 42.0 Web Browser. Does not seem to work
+    well with Google Chrome or Internet Explorer for some reason... they seem 
+    to generate two post requests which messes with the user input values. 
+    
+    3. There are a bunch of printf statements in the code that can be
+    uncommented for debugging in a serial terminal progrom. 
+
+    
+    TODO: ESP8366 has a max packet send size. Make sure we implement
+    a method to send webpages that exceed this value. The max size is
+    listed in the official ESP8266 AT Commands Documentation, I think
+    it is 2048 bytes/chars
+    
+    TODO: CREATE CONFIG FUNCTION TO SET SSID, PASSWORD, BAUDRATE ETC.
+    Perhaps have a serial terminal method to take user input, and 
+    put the function call into a #ifdef WiFiConfig statement, so 
+    that the user can enable it to config Wifi module then turn 
+    it off once Wifi module is configed so that this program can 
+    run in a "stand alone" mode. 
+
+    TODO: Move debugging printf statements inside of #ifdef DEBUG
+    statements, so that serial terminal print statements can be 
+    turned on and off easily for debugging.
+*/
+
+
+#include "mbed.h"
+#include "SDFileSystem.h"
+#include "PID.h"
+#include "QEI.h"
+#include <algorithm>
+
+/**********WEB SERVER SPECIFIC DECLARTATIONS**********************************/
+/*****************************************************************************/
+SDFileSystem sd(p5,p6,p7,p8,"sd");  // MOSI, MISO, SCLK, CS, 
+                                    // Virtual File System Name
+Serial esp(p13, p14);           // tx, rx
+DigitalOut  espRstPin(p26);     // ESP Reset
+DigitalOut led(LED4);
+
+Timer t1;
+Timer t2;
+
+void init(char* buffer, int size);
+void getreply(int timeout_ms, char* buffer, int size, int numBytes);
+void startserver(char* buffer, int size);
+void update_webpage(char* webpage, float setpoint, float kp, float ki, float kd);
+void parse_input(char* webpage_user_data, float* setpoint, float* kp, float* ki, float* kd);
+int port        =80;         // set server port
+int serverTimeout_secs =5;   // set server timeout in seconds in case 
+                             // link breaks.
+/*****************************************************************************/
+/*****************************************************************************/
+
+/*********PID CONTROLLER SPECIFIC DECLARATIONS********************************/
+/*****************************************************************************/
+static float setpoint, feedback, output;
+const float output_lower_limit = -1.0;          
+const float output_upper_limit = 1.0;
+const float FEEDBACK_SCALE = 1.0/3000.0;        // Scale feedback to 1rev/3000cnts
+                                                // this is encoder specific.
+const float setpoint_init = 0.0;
+const float kp_init = 0.01;
+const float ki_init = 0.01;
+const float kd_init = 0.0;
+const float Ts_init = 0.04;                   // 25Hz Sample Freq (40ms Sample Time)
+
+PID pid(&setpoint, &feedback, &output, output_lower_limit, output_upper_limit,
+        kp_init, ki_init,  kd_init, Ts_init);
+QEI encoder(p15, p16);
+PwmOut mtr_pwm(p25);
+DigitalOut mtr_dir(p24);
+void pid_callback();                             // Updates encoder feedback and motor output
+Ticker motor;
+/*****************************************************************************/
+/*****************************************************************************/
+
+// Common Application Declarations
+Serial pc(USBTX, USBRX);
+float clip(float value, float lower, float upper);
+
+int main()
+{
+    printf("Starting\n");
+    
+    /****************** Load Webpage from SD Card***************************************/
+    /***********************************************************************************/
+    char file[] = "/sd/pid_pos.html";
+    
+    // Get file size so we can dynamically allocate buffer size 
+    int num_chars = 0;
+    FILE *fp = fopen(file, "r");
+    while(!feof(fp)){
+        fgetc(fp);
+        num_chars++;
+    } 
+    rewind(fp);                     // Go to beginning of file
+
+//    printf("Webpage Data Size: %d byte\r\n", num_chars);
+
+    const int WEBPAGE_SIZE = num_chars;
+    char webpage[WEBPAGE_SIZE];                   
+    webpage[0] = NULL;               // Init our array so that element zero contains a null
+                                    // This is important, ensures strings are placed into
+                                    // buffer starting at element 0... not some random 
+                                    // elment                                           
+    // Read in and buffer file to memory
+    if(fp == NULL){
+         printf("Error: No Such File or something :(");
+         return 1;
+    }
+    else{
+        while(!feof(fp)){
+            fgets(webpage + strlen(webpage), WEBPAGE_SIZE, fp);  // Get a string from stream, add to buffer
+        }
+    }
+    fclose(fp);
+    printf("Webpage Buffer Size: %d bytes\r\n", sizeof(webpage));
+    update_webpage(webpage, setpoint, kp_init, ki_init, kd_init);   
+    /***********************************************************************************/
+    /***********************************************************************************/
+    
+    /***************BRING UP SERVER*****************************************************/
+    /***********************************************************************************/
+    char buff[5000];                // Working buffer
+    init(buff, sizeof(buff));       // Init ESP8266
+    
+    esp.baud(115200);               // ESP8266 baudrate. Maximum on KLxx' is 115200, 230400 works on K20 and K22F
+  
+    startserver(buff, sizeof(buff));      // Configure the ESP8266 and Setup as Server
+
+    printf(buff);     // If start successful buff contains IP address...
+                          // if not if contains an error.
+    led =1;
+    /***********************************************************************************/
+    /***********************************************************************************/
+    
+    /************Initialize the PID*****************************************************/
+    /***********************************************************************************/
+    // Working paramater variables
+    setpoint = setpoint_init;
+    encoder.reset();
+    feedback = encoder.read();
+    float kp = kp_init;
+    float ki = ki_init;
+    float kd = kd_init;
+    pid.set_parameters(kp, ki, kd, Ts_init);
+    
+    // Init the motor
+    mtr_dir = 0;            // Can be 0 or 1, sets the direction
+    mtr_pwm = 0.0;
+     
+    // Clear encoder count
+    encoder.reset();
+    
+    // Update sensors and feedback twice as fast as PID sample time
+    // this makes pid react in real-time avoiding errors due to 
+    // missing counts etc. 
+    motor.attach(&pid_callback, Ts_init/2.0);
+    
+    // Start PID sampling
+    pid.start();
+    
+    /***********************************************************************************/
+    /***********************************************************************************/
+    
+    while(1){
+        /**************SERVICE WEBPAGE******************************************************/
+        /***********************************************************************************/
+        if(esp.readable()){
+            getreply(500, buff, sizeof(buff), sizeof(buff) -1); // Get full buff, leave last element for null char
+//            printf("\r\n*************WORKING BUFFER******************************\r\n");
+//            printf(buff); printf("\n");
+//            printf("\r\n**************END WORKING BUFFER**************************\r\n");
+            
+            // If Recieved Data get ID, Length, and Data
+            char* rqstPnt = strstr(buff, "+IPD");
+            if(rqstPnt != NULL){
+                int id, len;
+                char type[10]; memset(type, '\0', sizeof(type)); // Create and null out data buff
+                sscanf(rqstPnt, "+IPD,%d,%d:%s ", &id, &len, type);
+//                printf("ID: %i\nLen: %i\nType: %s\n", id, len, type);
+                
+                // If GET or POST request "type" parse and update user input then send webpage
+                if(strstr(type, "GET") != NULL || strstr(type, "POST") != NULL){
+//                    printf("I got web request\n");
+                   
+                    /* Read Webpage <Form> data sent using "method=POST"...
+                       Note: Input elements in the <Form> need a set name attribute to 
+                       appear in the returned HTML body. Thus to "POST" data ensure:
+                       <Form method="POST"> <input type="xxx" name="xxx" value="xxx"> 
+                       <input type="xxx" value="xxx"> </Form>
+                       Only the input with name="xxx" will appear in body of HTML
+                    */
+ //                   printf("\r\n*************USER INPUT**********************************\r\n");
+                    parse_input(buff, &setpoint, &kp, &ki, &kd);
+                    setpoint = clip(setpoint, -999.99, 999.99);
+                    kp = clip(kp, 0.00, 999.99); 
+                    ki = clip(ki, 0.00, 999.99); 
+                    kd = clip(kd, 0.00, 999.99);
+//                    printf("User Entered: \nSetpoint: %7.2f\nKp: %6.2f\nKi: %6.2f\nKd: %6.2f\n", setpoint, kp, ki, kd);
+                    pid.set_parameters(kp, ki, kd, Ts_init);    // Updata PID params 
+ //                   printf("Updated to Kp: %1.2f Ki: %1.2f Kd: %1.2f Ts: %1.2f\r\n",
+ //                           pid.getKp(), pid.getKi(), pid.getKd(), pid.getTs());
+//                    printf("Setpoint: %1.2f\r\n", setpoint);
+//                    printf("Output: %1.2f\r\n", output);
+//                    printf("\r\n*************END USER INPUT******************************\r\n");
+                    
+                    // Update Webpage to reflect new values POSTED by client
+                    static bool isFirstRequest = true;
+                    if(!isFirstRequest) update_webpage(webpage, setpoint, kp, ki, kd);
+                    else isFirstRequest = false; // First Request just send page with initial values
+//                    printf(webpage); // DEBUGGING ONLY!!! REMOVE FOR RELEASE!!!
+                    
+                    // Command TCP/IP Data Tx
+                    esp.printf("AT+CIPSEND=%d,%d\r\n", id, strlen(webpage));
+                    getreply(200, buff, sizeof(buff), 15); /*TODO: Wait for "OK\r\n>"*/
+//                    printf(buff); printf("\n");
+                   
+                    // Send webpage
+//                    while(!esp.writeable());         // Wait until esp ready to send data
+                    int idx = 0;
+                    while(webpage[idx] != '\0'){
+                        esp.putc(webpage[idx]);
+                        idx++;
+                    }
+                   
+                    // Check status - Success: close channel and update PID controller, Error: reconnect 
+                    bool weberror = true;
+                    t2.reset(); t2.start();
+                    while(weberror ==1 && t2.read_ms() < 5000){
+                        getreply(500, buff, sizeof(buff), 24);
+                        if(strstr(buff, "SEND OK") != NULL) weberror = false;
+                    }
+                    if(weberror){
+                        esp.printf("AT+CIPMUX=1\r\n");
+                        getreply(500, buff, sizeof(buff), 10);
+  //                      printf(buff); printf("\n");
+                        
+                        esp.printf("AT+CIPSERVER=1,%d\r\n", port);
+                        getreply(500, buff, sizeof(buff), 10);
+ //                       printf(buff); printf("\n");
+                    }
+                    else{
+                        esp.printf("AT+CIPCLOSE=%d\r\n", id);  // Notice id is an int formatted to string
+                        getreply(500, buff, sizeof(buff), 24);
+//                        printf(buff); printf("\n");
+                    }
+                }       
+            }
+        }
+        /*********************************************************************/
+        /*********************************************************************/
+        
+        
+    }                      
+}
+
+// Initialize ESP8266
+void init(char* buffer, int size){
+    // Hardware Reset ESP 
+    espRstPin=0;
+    wait(0.5);
+    espRstPin=1;
+    // Get start up junk from ESP8266
+    getreply(6000, buffer, size, 500);
+}
+
+// Get Command and ESP status replies
+void getreply(int timeout_ms, char* buffer, int size, int numBytes)
+{
+    memset(buffer, '\0', size);     // Null out buffer
+    t1.reset();
+    t1.start();
+    int idx = 0;
+    while(t1.read_ms()< timeout_ms && idx < numBytes) {
+        if(esp.readable()) {
+            buffer[idx] = esp.getc();
+            idx++;
+        }
+    }
+    t1.stop();
+}
+
+// Starts and restarts webserver if errors detected.
+void startserver(char* buffer, int size)
+{
+    esp.printf("AT+RST\r\n");       // BWW: Reset the ESP8266          
+    getreply(8000, buffer, size, 1000);                                            
+
+    if (strstr(buffer, "OK") != NULL) {
+        // BWW: Set ESP8266 for multiple connections
+        esp.printf("AT+CIPMUX=1\r\n");
+        getreply(500, buffer, size, 20);
+        
+        // BWW: Set ESP8266 as Server on given port
+        esp.printf("AT+CIPSERVER=1,%d\r\n", port);
+        getreply(500, buffer, size, 20);   // BWW: Wait for reply
+        
+//        wait(1);
+        
+        // BWW: Set ESP8266 Server Timeout
+        esp.printf("AT+CIPSTO=%d\r\n", serverTimeout_secs);
+        getreply(500, buffer, size, 50);    // BWW: Wait for reply
+        
+//        wait(5);
+        
+        // BWW: Request IP Address from router for ESP8266 
+        int weberror = 0;
+        while(weberror==0) {
+            esp.printf("AT+CIFSR\r\n");
+            getreply(2500, buffer, size, 200);
+            if(strstr(buffer, "0.0.0.0") == NULL) {
+                weberror=1;   // wait for valid IP
+            }
+        }
+    } 
+    // else ESP8266 did not reply "OK" something is messed up
+    else {
+        strcpy(buffer, "ESP8266 Error\n");
+    }
+}
+
+/*
+    update_webpage() updates output fields based on webpage user inputs "POSTED"
+    Preconditions: webpage[] must have the following elements
+        "kp_output"  value="xxx.xx"
+        "ki_output"  value="xxx.xx"
+        "kp_output"  value="xxx.xx"
+    @param webpage  Pointer to webpage char[]
+    @param kp       New kp value posted by user
+    @param ki       New ki value posted by user
+    @param kd       New kd value posted by user
+    
+    NOTE: THIS IS WEBPAGE SPECIFIC!!!! CHANGE THE CODE IN HERE TO SUITE THE 
+    SPECIFIC APPLICATION WEBPAGE!!! ALSO USED TO REFLECT THE CUSTOM 
+    IMPLEMENTATION OF THE parse_intput() function. MAKE SURE THESE TWO FUNCTIONS 
+    INTEGRATE PROPERLY!!!
+*/
+void update_webpage(char* webpage, float setpoint, float kp, float ki, float kd){
+    // Change output value to reflect new setpoint kp, ki, kd values
+    char* begin; 
+//    char* end;
+    char temp[8];
+    int idx;
+    
+    memset(temp, '\0', sizeof(temp));
+    idx = 0;
+    begin = strstr(webpage, "name=\"kp_input\" value=\"") + 
+            sizeof("name=\"kp_input\" value="); // Points to start of kp_output field
+//    end = begin + 5;                                                      // Points to end of kp_output value 
+    // Determine precision of float such temp string has no empty spaces; 
+    // i.e. each space must have a value or a decimal point, other wise webbrowser may not recognize value
+    if(kp >= 100) sprintf(temp, "%6.2f", kp);                             // xxx.00
+    else if(10 <= kp && kp < 100) sprintf(temp, "%6.3f", kp);             // xx.000
+    else sprintf(temp, "%6.4f", kp);                                      // x.0000
+    while(temp[idx] !=  '\0'){                                            // Overwrite old digits with new digits
+        begin[idx] = temp[idx];
+        idx++;
+    }
+    
+    memset(temp, '\0', sizeof(temp));
+    idx = 0;
+    begin = strstr(webpage, "name=\"ki_input\" value=\"") + 
+            sizeof("name=\"ki_input\" value="); // Points to start of ki_output field
+//    end = begin + 5;                                                      // Points to end of ki_output value 
+    if(ki >= 100) sprintf(temp, "%6.2f", ki);                             // xxx.00
+    else if(10 <= ki && ki < 100) sprintf(temp, "%6.3f", ki);             // xx.000
+    else sprintf(temp, "%6.4f", ki);                                      // x.0000     
+    while(temp[idx] !=  '\0'){                                            // Overwrite old digits with new digits
+        begin[idx] = temp[idx];
+        idx++;
+    }
+    
+    memset(temp, '\0', sizeof(temp));
+    idx = 0;
+    begin = strstr(webpage, "name=\"kd_input\" value=\"")+
+            sizeof("name=\"kd_input\" value="); // Points to start of kd_output field
+//    end = begin + 5;                                                      // Points to end of kd_output value 
+    if(kd >= 100) sprintf(temp, "%6.2f", kd);                             // xxx.00
+    else if(10 <= kd && kd < 100) sprintf(temp, "%6.3f", kd);             // xx.000
+    else sprintf(temp, "%6.4f", kd);                                      // x.0000
+    while(temp[idx] !=  '\0'){                                            // Overwrite old digits with new digits
+        begin[idx] = temp[idx];
+        idx++;
+    }
+    
+    // Determine precision of float such temp string has no empty spaces; 
+    // i.e. each space must have a value or a decimal point or neg sign, 
+    // other wise webbrowser may not recognize value
+    memset(temp, '\0', sizeof(temp));
+    idx = 0;
+    begin = strstr(webpage, "name=\"setpoint_input\" value=\"")+
+            sizeof("name=\"setpoint_input\" value="); // Points to start of kp_output field
+//    end = begin + 6;                                                      // Points to end of kp_output value. +6 to accomadate negative sign 
+    if(setpoint >= 0.00){
+        if(setpoint >= 100) sprintf(temp, "%6.3f", setpoint);                           // xxx.000
+        else if(10 <= setpoint && setpoint < 100) sprintf(temp, "%7.4f", setpoint);     // xx.0000
+        else sprintf(temp, "%6.5f", setpoint);                                          // x.00000
+    }
+    else{
+        if(setpoint <= -100) sprintf(temp, "%6.2f", setpoint);                          // -xxx.00
+        else if(-100 < setpoint && setpoint <= -10) sprintf(temp, "%6.3f", setpoint);   // -xx.000
+        else sprintf(temp, "%6.4f", setpoint);                                          // -x.0000
+    }
+    while(temp[idx] !=  '\0'){                                            // Overwrite old digits with new digits
+        begin[idx] = temp[idx];
+        idx++;
+    }
+}
+
+/*
+    parse_input() take a char*, in particular a pointer to Webpage User 
+    Input Data, for example: 
+    char str[] = "+IPD,0,44:kp_input=0.12&ki_input=14.25&kd_input=125.42";
+    
+    and parses out the Setpoint Kp, Ki, Kd values that the user entered
+    and posted in the webpage. Values are converted to floats and 
+    assigned to the given argurments.
+    
+    NOTE: THIS IS WEBPAGE SPECIFIC!!!! CHANGE THE CODE IN HERE TO SUITE THE 
+    SPECIFIC APPLICATION WEBPAGE!!! THESE EXTRACTED VALUES WILL BE USED IN 
+    THE update_webpage() function. MAKE SURE THESE TWO FUNCTIONS INTEGRATE
+    PROPERLY!!!
+*/
+void parse_input(char* webpage_user_data,float *setpoint, float* kp, float* ki, float* kd){
+    char keys[] = {'&', '\0'};
+      
+    // Parse out user input values
+    char input_buff[50]; 
+    char* begin;
+    char* end;
+//    printf("**************Parsing**************\n");
+    memset(input_buff, '\0', sizeof(input_buff));           // Null out input buff
+    begin = strstr(webpage_user_data, "setpoint_input=") +
+            sizeof("setpoint_input");                       // Points to start of setpoint_input value
+    end = begin + strcspn(begin, keys);                     // Points to end of setpoint_input value
+    for(long i = 0; i < end - begin; i++){                  // Parse out the value one char at a time
+        input_buff[i] = begin[i];        
+    }
+//    printf("Setpoint Parsed Data: %s\n", input_buff);
+    *setpoint = atof(input_buff);
+    
+    memset(input_buff, '\0', sizeof(input_buff));           // Null out input buff
+    begin = strstr(webpage_user_data, "kp_input=") + 
+            sizeof("kp_input");                             // Points to start of kp_input value
+    end = begin + strcspn(begin, keys);                     // Points to end of kp_input value
+    for(long i = 0; i < end - begin; i++){                  // Parse out the value one char at a time
+        input_buff[i] = begin[i];
+    }
+//    printf("Kp Parsed Data: %s\n", input_buff);
+    *kp = atof(input_buff);
+    
+    memset(input_buff, '\0', sizeof(input_buff));           // Null out input buff
+    begin = strstr(webpage_user_data, "ki_input=") + 
+            sizeof("ki_input");                             // Points to start of ki_input value
+    end = begin + strcspn(begin, keys);                     // Points to end of ki_input value
+    for(long i = 0; i < end - begin; i++){                  // Parse out the value one char at a time
+        input_buff[i] = begin[i];
+    }
+//   printf("Ki Parsed Data: %s\n", input_buff); 
+    *ki = atof(input_buff);
+    
+    memset(input_buff, '\0', sizeof(input_buff));           // Null out input buff
+    begin = strstr(webpage_user_data, "kd_input=") + 
+            sizeof("kd_input");                             // Points to start of kd_input value
+    end = begin + strcspn(begin, keys);                     // Points to end of kd_input value
+    for(long i = 0; i < end - begin; i++){                  // Parse out the value one char at a time
+        input_buff[i] = begin[i];  
+    }
+//    printf("Kd Parsed Data: %s\n", input_buff);
+    *kd = atof(input_buff);
+//    printf("**********End Parsing***************\n");
+}
+
+void pid_callback(){
+    // Update motor
+    if(setpoint >= 0.0) mtr_dir = 1;       // Set motor direction based on setpoint
+    else mtr_dir = 0;
+    if(-0.001 < setpoint && setpoint < 0.001){ 
+        /* Setpoint = 0 is a special case, we allow output to control speed AND 
+        direction to fight intertia and/or downhill roll. */
+        if(output >= 0.0) mtr_dir = 1;
+        else mtr_dir = 0;
+        mtr_pwm = abs(output);
+    }
+    else{    
+        if(mtr_dir == 1){                      // If CW then apply positive outputs
+            if(output >= 0.0) mtr_pwm = output;
+            else mtr_pwm = 0.0;
+        }
+        else{                                // If CCW then apply negative outputs
+            if(output <= 0.0) mtr_pwm = abs(output);
+            else mtr_pwm = 0.0;
+        }                          
+    } 
+    float k = Ts/2.0;                        // Discrete time, (Ts/2 because this callback is called
+                                             // at interval of Ts/2... or twice as fast as pid controller)
+    
+    /* TODO: Implement a "rolling"/"moving" average */
+    static int last_count = 0;
+    int count = encoder.read();
+    float raw_speed = ((count - last_count)*FEEDBACK_SCALE) / k; 
+    float rpm_speed = raw_speed * 60.0;     // Convert speed to RPM
+    
+    last_count = count;                     // Save last count
+    feedback = rpm_speed;  
+}
+
+/*
+    Clips value to lower/ uppper
+    @param value    The value to clip
+    @param lower    The mininum allowable value
+    @param upper    The maximum allowable value
+    @return         The resulting clipped value
+*/
+float clip(float value, float lower, float upper){
+    return std::max(lower, std::min(value, upper));
+}
+
+/**************************WEB PAGE TEXT**************************************/
+/*****************************************************************************
+Copy and past text below into a html file and save as the given file name to 
+your SD card.
+
+file name: pid_pos.html
+
+html text:
+
+
+*****************************************************************************/
+/*****************************************************************************/
\ No newline at end of file
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.bld	Wed Nov 25 02:11:34 2015 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/mbed_official/code/mbed/builds/9296ab0bfc11
\ No newline at end of file