Isaac Lee
Bluetooth app controlled robot
Dependencies: ESP8266 HALLFX_ENCODER LSM9DS1_Library_cal MotorDriver PID mbed
Fork of
ESP8266_pid_redbot_webserver
by 
Bryce Williams
Diff: main.cpp
- Revision:
- 0:11bc7a815367
- Child:
- 1:d4a95e3a8aeb
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp Fri Nov 27 15:30:19 2015 +0000
@@ -0,0 +1,657 @@
+/*
+ Uses the ESP8266 WiFi Chip to set up a WiFi Webserver used to control
+ the position or 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: Implement stop button in webpage
+*/
+
+
+#include "mbed.h"
+#include "SDFileSystem.h"
+#include "PID.h"
+#include "QEI.h"
+#include <algorithm>
+
+//#define DEBUG // Uncomment for serial terminal print debugging
+ // Comment out to turn prints off for normal op
+
+/*********PID CONTROLLER SPECIFIC DECLARATIONS********************************/
+/*****************************************************************************/
+
+float setpoint, feedback, output; // Should these be volatile?
+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.
+enum CONTROL_MODE{POSITION = 0, SPEED = 1};
+bool control_mode = POSITION;
+float kp, ki, kd; // Gain variables for working
+const float Ts = 0.04; // 25Hz Sample Freq (40ms Sample Time)
+const float Ts_PID_CALLBACK = Ts/2.0; // Update Motors and sensers twice as
+ // fast as PID sample rate, ensures
+ // PID feedback is upto date every
+ // time PID calculations run
+
+// Vars to store gains for Speed and Position when switching Control modes
+const float kp_init = 2.5; // Good Kp for Position Control
+const float ki_init = 5.0; // Good Ki for Position Control
+const float kd_init = 0.25; // Good Kd for Position Control
+
+PID pid(&setpoint, &feedback, &output,
+ output_lower_limit, output_upper_limit,
+ kp_init, ki_init, kd_init, Ts); // Init for position control
+QEI encoder(p15, p16);
+PwmOut mtr_pwm(p25);
+DigitalOut mtr_dir(p24);
+void pid_callback(); // Updates encoder feedback and motor output
+Ticker motor;
+/*****************************************************************************/
+/*****************************************************************************/
+
+/**********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, bool* control_mode, 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.
+/*****************************************************************************/
+/*****************************************************************************/
+
+// 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_dual.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
+
+ #ifdef DEBUG
+ printf("Webpage Data Size: %d byte\r\n", num_chars);
+ #endif
+
+ 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); // Update Webpage for
+ // Position Mode
+ /***********************************************************************************/
+ /***********************************************************************************/
+
+ /***************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.
+ /***********************************************************************************/
+ /***********************************************************************************/
+
+ /************Initialize the PID*****************************************************/
+ /***********************************************************************************/
+ setpoint = 0.0;
+ encoder.reset();
+ feedback = encoder.read();
+
+ // Init the motor
+ mtr_dir = 0; // Can be 0 or 1, sets the direction
+ mtr_pwm = 0.0;
+
+ // 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_PID_CALLBACK);
+
+ // 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
+ #ifdef DEBUG
+ printf("\r\n*************WORKING BUFFER******************************\r\n");
+ printf(buff); printf("\n");
+ printf("\r\n**************END WORKING BUFFER**************************\r\n");
+ #endif
+ // 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);
+ #ifdef DEBUG
+ printf("ID: %i\nLen: %i\nType: %s\n", id, len, type);
+ #endif
+ // If GET or POST request "type" parse and update user input then send webpage
+ if(strstr(type, "GET") != NULL || strstr(type, "POST") != NULL){
+ #ifdef DEBUG
+ printf("I got web request\n");
+ #endif
+ /* 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
+ */
+ #ifdef DEBUG
+ printf("\r\n*************USER INPUT**********************************\r\n");
+ #endif
+
+ parse_input(buff, &control_mode, &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);
+
+ #ifdef DEBUG
+ printf("User Entered: \ncontrol_mode: %i\nSetpoint: %7.4f\nKp: %6.4f\nKi: %6.4f\nKd: %6.4f\n",
+ control_mode, setpoint, kp, ki, kd);
+ #endif
+
+ pid.set_parameters(kp, ki, kd, Ts); // Updata PID params
+
+ #ifdef DEBUG
+ printf("Updated to Kp: %1.4f Ki: %1.4f Kd: %1.4f Ts: %1.4f\r\n",
+ pid.getKp(), pid.getKi(), pid.getKd(), pid.getTs());
+ printf("Setpoint: %1.4f\r\n", setpoint);
+ printf("Output: %1.4f\r\n", output);
+ printf("\r\n*************END USER INPUT******************************\r\n");
+ #endif
+
+ // 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
+
+ #ifdef DEBUG
+ printf(webpage); // DEBUGGING ONLY!!! REMOVE FOR RELEASE!!!
+ #endif
+
+ // 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>"*/
+
+ #ifdef DEBUG
+ printf(buff); printf("\n");
+ #endif
+
+ // 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);
+ #ifdef DEBUG
+ printf(buff); printf("\n");
+ #endif
+ esp.printf("AT+CIPSERVER=1,%d\r\n", port);
+ getreply(500, buff, sizeof(buff), 10);
+ #ifdef DEBUG
+ printf(buff); printf("\n");
+ #endif
+ }
+ else{
+ esp.printf("AT+CIPCLOSE=%d\r\n", id); // Notice id is an int formatted to string
+ getreply(500, buff, sizeof(buff), 24);
+ #ifdef DEBUG
+ printf(buff); printf("\n");
+ #endif
+ }
+ }
+ }
+ }
+ /*********************************************************************/
+ /*********************************************************************/
+
+
+ }
+}
+
+// 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
+
+ // BWW: Set ESP8266 Server Timeout
+ esp.printf("AT+CIPSTO=%d\r\n", serverTimeout_secs);
+ getreply(500, buffer, size, 50); // BWW: Wait for reply
+
+ // 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 control mode, setpoint, kp, ki, kd values
+ char* begin;
+ char temp[8];
+ int idx;
+
+ // Update Control Mode Radio Buttons
+ memset(temp, '\0', sizeof(temp));
+ idx = 0;
+ begin = strstr(webpage, "name=\"control_mode\" value=\"") +
+ sizeof("name=\"control_mode\" value=\"0"); // Update Control Mode Position Radio Button
+ if(control_mode == POSITION) sprintf(temp, "%s", "checked");// If Position active "check" it
+ else sprintf(temp, "%s", " "); // else "clear" it
+ while(temp[idx] != '\0'){ // Write "checked"/" " to field
+ begin[idx] = temp[idx];
+ idx++;
+ }
+ memset(temp, '\0', sizeof(temp));
+ idx = 0;
+ begin = strstr(webpage, "name=\"control_mode\" value=\"") +
+ sizeof("name=\"control_mode\" value=\"0\""); // Nav to first Control Mode Radio Button (Position)
+ begin = strstr(begin, "name=\"control_mode\" value=\"") +
+ sizeof("name=\"control_mode\" value=\"1"); // Nav to second Control Mode Radio Button (Speed)
+ if(control_mode == SPEED) sprintf(temp, "%s", "checked"); // If Speed active "check" it
+ else sprintf(temp, "%s", " "); // else "clear" it
+ while(temp[idx] != '\0'){ // Write "checked"/" " to field
+ begin[idx] = temp[idx];
+ idx++;
+ }
+
+ // Update Kp Paramater Field
+ 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
+ // 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++;
+ }
+
+ // Update Ki Parameter Field
+ 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
+ // 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(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++;
+ }
+
+ // Update Kd Parameter Field
+ 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
+ // 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(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++;
+ }
+
+ // Update Setpoint Parameter Field
+ // 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
+ // 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(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, bool* control_mode, float *setpoint, float* kp, float* ki, float* kd){
+ char keys[] = {'&', '\0'};
+
+ // Parse out user input values
+ char input_buff[50];
+ char* begin;
+ char* end;
+
+ // Parse and Update Control Mode Value
+ memset(input_buff, '\0', sizeof(input_buff)); // Null out input buff
+ begin = strstr(webpage_user_data, "control_mode=") +
+ sizeof("control_mode"); // 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];
+ }
+ *control_mode = atoi(input_buff);
+
+ // Parse and Update Setpoint Value
+ 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];
+ }
+ *setpoint = atof(input_buff);
+
+ // Parse and Update Kp Value
+ 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];
+ }
+ *kp = atof(input_buff);
+
+ // Parse and Update Ki Value
+ 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];
+ }
+ *ki = atof(input_buff);
+
+ // Parse and Update Kd Value
+ 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];
+ }
+ *kd = atof(input_buff);
+}
+
+void pid_callback(){
+ // If control_mode is POSITION run position pid
+ if(control_mode == POSITION){
+ // Update motor
+ if(output >= 0.0) mtr_dir = 1; // Set direction to sign of output
+ else mtr_dir = 0;
+ mtr_pwm = abs(output); // Apply motor output
+
+ // Update feedback
+ feedback = encoder.read()*FEEDBACK_SCALE;// Scale feedback to num wheel revs
+ }
+ // else control_mode must be SPEED, run speed pid
+ else{
+ 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_dual.html
+
+html text:
+
+<!DOCTYPE html>
+<html>
+<head>
+<title>PID Motor Control</title>
+</head>
+<body>
+<h1>PID Motor Control</h1>
+<h2>Motor Status</h2>
+<p>
+<form title="Motor Status">
+<input type="text" value="Some user information" size="25" readonly /><br>
+Current Setpoint:
+<input type="number" name="current_setpoint" value="0000.00" readonly /><br>
+Current Position:
+<input type="number" name="current_position" value="0000.00" readonly /><br>
+</form>
+</p>
+<h2>PID Status</h2>
+<form title="User Input" method="post">
+PID Controls: <br>
+<input type="radio" name="control_mode" value="0"checked>Position(#Revolutions)
+<br>
+<input type="radio" name="control_mode" value="1" >Speed(RPM)
+<br>
+Setpoint:
+<input type="number" name="setpoint_input" value="0000.00" step="0.0000001" size="6" /><br>
+Proportional Gain: (Good Starting Values: Position = 2.50 Speed = 0.01)<br>
+<input type="number" name="kp_input" value="002.50" step="0.0000001" size="6" /><br>
+Integral Gain: (Good Starting Values: Position = 5.0 Speed = 0.015)<br>
+<input type="number" name="ki_input" value="005.00" step="0.0000001" size="6" /><br>
+Derivative Gain: (Good Starting Values: Position = 0.25 Speed = 0.0001)<br>
+<input type="number" name="kd_input" value="000.25" step="0.0000001" size="6" /><br>
+<br>
+<input type="submit" value="Update" />
+</form>
+</body>
+</html>
+
+*****************************************************************************/
+/*****************************************************************************/
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