Arduino stepper control by program - arduino

Question

I try to control a stepper motor with a program that uses a protocol (see below)
I am able to control the stepper with the Accelstepper (see below) but have no idea how i can program the Arduino so it is able to communicate according te protocol through the serial port.
#include <AccelStepper.h>
// Define a stepper and the pins it will use
AccelStepper stepper(1, 3, 4);
int pos = 8192;
void setup()
{
stepper.setMaxSpeed(5000);
stepper.setAcceleration(1500);
}
void loop()
{
if (stepper.distanceToGo() == 0)
{
delay(500);
pos = -pos;
stepper.moveTo(pos);
}
stepper.run();
}
All commands sent to the rotary table are in simple character format including the motor numbers. Only the parts marked as xxx passed to the table as byte data. For example if you want table 1 rotate 4 steps instead of passing "I1M004" you pass "I1M" + (char)0 + (char)0 + (char)4
In general all commands get a reply in the form of: ^XXXXXX
Commands
V
Request the status of the rotary table. Usual reply would be ^R1R2R3R4 indicating rotary 1 ready, rotary 2 ready, etc. ^B1xxxR2R3R4 means rotary 1 is busy where xxx are 3 bytes indicates how many steps the rotary still has to perform.
SmMxxx
Sets the speed of the motor m to xxx, where xxx is a 3 bytes of data indicating the speed. Example code: port.Write("S1M" + (char)0 + (char)6 + (char)255); // set motor 1 to speed 1791. The standard speed range of our rotary table is: 0x000001 to 0x0012FF (1 to 4863). Controller will respond with ^mxx mirroring the motor number and 2 last bytes of speed setting.
ImMxxx
Turns motor m xxx number of steps. Controller will acknowledge with ^Bmxxx
DmCWLO
Set motor number m to rotate clockwise (So each consecutive command to rotate the motor m will rotate it clockwise).
DmCWHi
Sets rotary m to rotate counterclockwise.
EmHALT
Rotary m stop.
Rotary Sample Command Sequence
Motor numbers are passed as characters but the number of steps and speed are passed as 3 bytes of binary for simplicity.
send: V reply: ^R1R2R3R4
send: S1M1791 reply: ^191
send: D1CWLO reply: ^
send: I1M100 reply: ^B1100

Answer 1

I had a similar project for my dissertation work where I controlled an inverted pendulum from a PC via an arduino uno. I'm assuming you have a PC program what sends out the commands to the arduino, and the problem is to receive and interpret it on the Arduino board.
I wrote the code below with major help (some copy paste modify) from here
It basically opens the com port and then listens to the incoming commands from the PC. When a command is received, it breaks it up (the incoming commands come in a #00parameter format). All commands start with #. The following 2 digits define the command itself, and the following text/numbers are the parameters for the command.
Once the command and its parameters are known, the actual process related to the command can be executed. In your case this supposed to be the motor control related to the incoming commands. The below code obviously needs to be updated to match with your motor control functions, but the incoming command handling works just fine.
String inputString = ""; // a string to hold incoming data
boolean stringComplete = false; // whether the incloming string is complete
float kp = 10; //sample parameter 1
float kd = 5; //sample parameter 2
float ki = 2; //sample parameter 3
void setup()
{
Serial.begin(9600); //Start serial communication
inputString.reserve(200); //Reserves 200 bytes for the string
}
void loop()
{
//This becomes true when the serial port receives a "\n" character (end of line)
if (stringComplete)
{
SerialProc(); //the function which runs when a full line is received
inputString = ""; //once processed, the string is cleared
stringComplete = false; //set flag to false to indicate there is nothing in the buffer waiting
}
}
void serialEvent() //This serial event runs between each loop cycles
{
while (Serial.available()) //if there is anything in the incoming buffer this while loop runs
{
// get the next new byte:
char inChar = (char)Serial.read();
// add it to the inputString:
inputString += inChar;
// if the incoming character is a newline, set a flag
// so the main loop can do something about it:
if (inChar == '\n')
{
stringComplete = true; //This indicates the line is complete, and the main program can process it
}
}
}
void SerialProc() //the function which processes the incoming commands. It needs to be modified to your needs
{
//cmd is the first three characters of the incoming string / line
String cmd = inputString.substring(0,3); //first three characters in incoming string specifies the command
//param is the rest of the string to the end of the line (excluding the first three characters)
String param = inputString.substring(3, inputString.length()); //rest of incoming string is making up the parameter
//creating a buffer as an array of characters, same size as the length of the parameters string
char buf[param.length()];
//moving the parameters from string to the char array
param.toCharArray(buf,param.length());
//the above string to char array conversion is required for the string to float
//conversion below (atof)
//the below part is the command execution. Could have used a switch below, but the series of ifs
//just did the trick
if (cmd == "#00")
SendReply(); //Executing command 1
else if (cmd == "#01")
kp = atof(buf); //executing command 2 (setting parameter kp)
else if (cmd == "#02")
kd = atof(buf); //executing command 3 (setting parameter kd)
else if (cmd == "#03")
ki = atof(buf); //executing command 4 (setting parameter ki)
}
void SendReply()
{
//This is called from the SerialProc function when the #00 command is received
//After the last parameter (TimeDelay) it sends the carrige return characters via the Serial.println
Serial.println("reply");
}