Using an Arduino as a slave board

Arduino serial interfacing and basic function library

The Arduino Code

The Liberty Basic Demo

Just the Library and function descriptions

By Mike Molianri

Home automation, Robots, Vending machines. What do they have in common?

The answer is computers controlling hardware. Making lights go on and off. Controlling motors, relays and other electronic components.
Liberty Basic for windows makes programming simple but lacks the ability to directly control or interface with hardware (except the parallel port).

To make hardware interface coding simpler a set of functions is required to facilitate the communication with external hardware. Because the arduino is the most widely used hobby micro controller in the world and has so much support it is the obvious choice make a set of simple functions for LB users to take advantage of this great platform for there projects.

The things covered in this article are limited to simple port I/O (Input and output).

Test if pin is high or low
- Get input from buttons and other sensors connected to the arduino
Set a pin high or low
- Turn things on and off like lights, buzzers, motors, ect.
PWM (Pulse width modulation) output
- Dim lights, Control servo motors, interface with variable speed motor controllers
PWM (Pulse width modulation) input
- Get input from things like sliders and position information

The Arduino Code

To make liberty basic talk with an arduino they have to speak the same language.
In this case a string is used and send over to the device followed by a carriage return character CHR$(13)

The only thing you really have to understand about the arduino code is that it must be download to the arduino board using the arduino IDE.
This can be download from the following link.
http://arduino.cc/en/Main/Software

Note: This code is done in arduinos special form of c and is not basic code.

 // Buffer to store incoming commands from serial port 
 String inData; 
 
 void setup() { 
 Serial.begin(9600); 
 Serial.println("Serial conection started, waiting for instructions..."); 
 } 
 
 void loop() { 
 while (Serial.available() > 0) 
 { 
 char recieved = Serial.read(); 
 inData += recieved; 
 
 // Process message when new line character is recieved 
 if (recieved == '\n') 
 { 
 String Param0 = getValue(inData, ' ', 0); 
 String Param1 = getValue(inData, ' ', 1); 
 String Param2 = getValue(inData, ' ', 2); 
 String Param3 = getValue(inData, ' ', 3); 
 String Param4 = getValue(inData, ' ', 4); 
 String Param5 = getValue(inData, ' ', 5); 
 
 inData = ""; 
 
 int valParam0 = Param0.toInt(); 
 int valParam1 = Param1.toInt(); 
 int valParam2 = Param2.toInt(); 
 int valParam3 = Param3.toInt(); 
 int valParam4 = Param4.toInt(); 
 int valParam5 = Param5.toInt(); 
 
 
 //Serial.print(valParam0); 
 //Serial.print(valParam1); 
 //Serial.print(valParam2); 
 //Serial.print(valParam3); 
 //Serial.print(valParam4); 
 //Serial.print(valParam5); 
 
 
 
 
 if ( Param0 == "get") 
 { 
 pinMode(valParam1, INPUT); 
 Serial.println(digitalRead(valParam1)); 
 
 
 } 
 
 if ( Param0 == "set") 
 { 
 pinMode(valParam1, OUTPUT); 
 digitalWrite(valParam1, valParam2); 
 Serial.println("1"); 
 
 
 } 
 
 
 if ( Param0 == "pwm.out") 
 { 
 analogWrite(valParam1, valParam2); 
 Serial.println("1"); 
 
 } 
 
 
 
 if ( Param0 == "pwm.in") 
 { 
 Serial.println(analogRead(valParam1)); 
 } 
 
 } 
 } 
 } 
 
 
 
 
 String getValue(String data, char separator, int index) 
 { 
 int found = 0; 
 int strIndex[] = { 
 0, -1 }; 
 int maxIndex = data.length()-1; 
 for(int i=0; i<=maxIndex && found<=index; i++){ 
 if(data.charAt(i)==separator || i==maxIndex){ 
 found++; 
 strIndex[0] = strIndex[1]+1; 
 strIndex[1] = (i == maxIndex) ? i+1 : i; 
 } 
 } 
 return found>index ? data.substring(strIndex[0], strIndex[1]) : ""; 
 }

The Liberty Basic Demo

The demo program shows off the basic functionality of the library.

The Com port that the arduino is on must be placed in the com port number text box.

A pin must be selected and a value to send must be entered.

The 4 buttons on the right are used to execute the functions.

The return value is populated by the what is returned by the arduino.

Just the Library and function descriptions

The bare naked functions are below with commented explanations for what they do.

 'Begin Arduino Code here ------------------------------------------------------- 
 'These functions can be added to any program to provide arduini power input and output 
 'Descriptions for functions are in there comments 
 
 
 function AD.Set(com.port, PinNo, value) 
 'Set an Arduino pin high or low, 
 'Will return 1 one if successful, 0 if not 
 AD.Set = val(AD.talk.to.device$(com.port,"set ";PinNo;" ";value)) 
 end function 
 
 
 function AD.Get(com.port, PinNo) 
 'Will return the current state of the input pin 
 '1 for high, 0 for low 
 AD.Get = val(AD.talk.to.device$(com.port,"get ";PinNo)) 
 end function 
 
 
 function AD.PWM.Out(com.port, PinNo, value) 
 'Set the PWM output on the select pin to the value 
 'Will return a 1 for success and 0 for failure. 
 AD.PWM.Out = val(AD.talk.to.device$(com.port,"pwm.out ";PinNo;" ";value)) 
 end function 
 
 
 function AD.PWM.In(com.port, PinNo) 
 'Get the PWM input from the pin 
 'Will return a value of 0 to 1023 
 AD.PWM.In = val(AD.talk.to.device$(com.port,"pwm.in ";PinNo)) 
 end function 
 
 
 
 Function AD.talk.to.device$(port,msg$) 
 'Send a Message to the arduino and return the result sent back by the device 
 if msg$ <> "" then 
 'Open the com port 
 open "COM" ; port ; ":9600,n,8,1" for random as #ArduinoCOMPort 
 
 'Send message to device 
 print #ArduinoCOMPort, msg$ 
 
 'Wait until there is a carriage return 
 while foundLF = 0 
 while lof(#ArduinoCOMPort) > 0 
 temp$ = input$(#ArduinoCOMPort, 1) 
 buffer$ = buffer$ + temp$ 
 
 if temp$ = chr$(13) then 
 foundLF = 1 
 exit while 
 end if 
 wend 
 wend 
 
 'Place the returned text in to AD.talk.to.device$ 
 AD.talk.to.device$ = buffer$ 
 close #ArduinoCOMPort 
 else 
 Notice "Improper Message Received, Must contain a command" 
 end if 
 End function