Arduino sketch that reads serial characters as a command and does something - ios5

Question

Currently I am trying to get a sketch working where the Arduino will read a series of characters as a command, and do something based on the series of characters sent from an iDevice. I am using an iPhone 3GS that is jailbroken to send characters to the Arduino. The method that sends the serial characters looks like the following,
- (IBAction)blinkFlow_A_LED:(id)sender {
// Method to blink the Flow_A LED on the kegboard-mini Arduino shield (<https://github.com/Kegbot/kegboard>).
NSLog(#"blink Flow_A btn pressed");
// Open serial port / interface
[serial open:B2400];
NSLog(#"%c", [serial isOpened]);
// Send serial data (TX)
char buffer [7];
buffer[0] = '{';
buffer[1] = 'b';
buffer[2] = 'l';
buffer[3] = 'i';
buffer[4] = 'n';
buffer[5] = 'k';
buffer[6] = '}';
[serial write:buffer length:7];
}
I have created a simple sketch that blinks the LED on the shield I am using, but I want the LED to blink conditionally when the button is clicked in the iOS app. The sketch that blinks the LED looks like the following,
/*
Blink
Turns on an LED on for one second, then off for one second, repeatedly.
This sketch is specific to making the kegboard-mini shield.
http://arduino.cc/forum/index.php?topic=157625.new;topicseen#new
This example code is in the public domain.
*/
// Pin D4 - should be connected to the flow_A LED
// Give it a name
int led = 4;
// The setup routine runs once when you press reset:
void setup() {
// Initialize the digital pin as an output.
pinMode(led, OUTPUT);
}
// The loop routine run over and over again forever:
void loop() {
digitalWrite(led, HIGH); // Turn the LED on (HIGH is the voltage level)
delay(1000); // Wait for one second
digitalWrite(led, LOW); // Turn the LED off by making the voltage LOW
delay(1000); // Wait for a second
}

Answer 1

That is a simple sketch!
You may want to begin with looking at the Arduino reference page: Serial
In setup(), you need at least Serial.begin(2400);.
Now, I'll suggest that reading and decoding the string "{blink}" seems like overkill. Let me suggest you send one character (for example 'b'), and detect one character, at least to start. Check out .available() and .read() on the Serial reference page. With these you can determine if a character has arrived at the Arduino and read in a single character.
You can then use these if you want to build a string of characters one at a time and compare it to String("{blink}"). This is a bit more complicated, especially if you take into account exceptions (like lost or damaged characters).
You can easily test your program using the Serial monitor tool -- just be advised that you have to hit "send" to make the characters go out.

Answer 2

I ended putting a simple sketch together like this which allows me to store an array of serial bytes into a String thanks to the SerialEvent example.
The sketch I am currently working with looks like the following,
/*
* kegboard-serial-simple-blink07
* This code is public domain
*
* This sketch sends a receives a multibyte String from the iPhone
* and performs functions on it.
*
* Examples:
* http://arduino.cc/en/Tutorial/SerialEvent
* http://arduino.cc/en/Serial/read
*/
// Global variables should be identified with "_"
// flow_A LED
int led = 4;
// relay_A
const int RELAY_A = A0;
// Variables from the sketch example
String inputString = ""; // A string to hold incoming data
boolean stringComplete = false; // Whether the string is complete
void setup() {
Serial.begin(2400); // Open a serial port. Sets data rate to 2400 bit/s
Serial.println("Power on test");
inputString.reserve(200);
pinMode(RELAY_A, OUTPUT);
}
void open_valve() {
digitalWrite(RELAY_A, HIGH); // Turn RELAY_A on
}
void close_valve() {
digitalWrite(RELAY_A, LOW); // Turn RELAY_A off
}
void flow_A_blink() {
digitalWrite(led, HIGH); // Turn the LED on (HIGH is the voltage level)
delay(1000); // Wait for one second
digitalWrite(led, LOW); // Turn the LED off by making the voltage LOW
delay(1000); // Wait for a second
}
void flow_A_blink_stop() {
digitalWrite(led, LOW);
}
void loop() {
// Print the string when newline arrives:
if (stringComplete) {
Serial.println(inputString);
// Clear the string:
inputString = "";
stringComplete = false;
}
if (inputString == "{blink_Flow_A}") {
flow_A_blink();
}
}
// SerialEvent occurs whenever a new data comes in the
// hardware serial RX. This routine is run between each
// time loop() runs, so using delay inside loop can delay
// response. Multiple bytes of data may be available.
void serialEvent() {
while(Serial.available()) {
// Get the 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;
}
}
}