Sitting at a teacher conference one day, my booth partner asked me how long it would take me to build a line following arduino robot. I looked around at the parts we had on hand: an arduino UNO, a pile of 10k resistors and photovoltaic resistors, continuous servos, coffee cups, wire, tape, and a nine volt battery.
I said “an hour.”
He said “Prove it.”
When I’m developing Arduino code, I often have variables that need to be tweaked during testing & calibration.
Rather than recompile and upload the code (a time consuming process) I wrote a few lines to let me open the Serial Monitor and send commands directly.
I hope you find this useful – I use it in all my robots!
#define DELAY (5)
#define BAUD (57600)
#define MAX_BUF (64)
char buffer[MAX_BUF];
int sofar;
char test_on=0; // only used in processCommand as an example.
float pos_x;
float pos_y;
float pos_z;
void jog(float x, float y, float z) {
// do some tests here to validate x, y, and z.
pos_x=x;
pos_y=y;
pos_z=z;
}
void processCommand() {
if(!strncmp(buffer,"help",4)) {
Serial.println("commands: where; test (1/0); jog [x(float)] [y(float)] [z(float)];");
} else if(!strncmp(buffer,"where",5)) {
// no parameters
Serial.print(pos_x);
Serial.print(", ");
Serial.print(pos_y);
Serial.print(", ");
Serial.println(pos_z);
} else if(!strncmp(buffer,"test",4)) {
// one whole number parameter
char *state=strchr(buffer,' ')+1;
Serial.println(state);
if(state[0]=='0') {
Serial.println("End test");
test_on=0;
} else {
Serial.println("Start test");
test_on=1;
}
} else if(!strncmp(buffer,"jog",3)) {
// several optional float parameters.
// then calls a method to do something with those parameters.
float xx=pos_x;
float yy=pos_y;
float zz=pos_z;
char *ptr=buffer;
while(ptr && ptr < buffer+sofar) {
ptr=strchr(ptr,' ')+1;
switch(*ptr) {
case 'x': case 'X': xx=atof(ptr+1); Serial.print('x'); Serial.println(xx); break;
case 'y': case 'Y': yy=atof(ptr+1); Serial.print('y'); Serial.println(yy); break;
case 'z': case 'Z': zz=atof(ptr+1); Serial.print('z'); Serial.println(zz); break;
default: ptr=0; break;
}
}
jog(xx,yy,zz);
}
}
void setup() {
Serial.begin(BAUD);
Serial.println("Init...");
Serial.println("Stretching...");
sofar=0;
Serial.println(F("** AWAKE **"));
Serial.print(F("\n> "));
}
void loop() {
// listen for serial commands
while(Serial.available() > 0) {
char c = Serial.read();
if(sofar < MAX_BUF-1)
buffer[sofar++]=c;
if(c=='\n') {
// echo confirmation
buffer[sofar]=0;
Serial.println(buffer);
// do something with the command
processCommand();
// reset the buffer
sofar=0;
// ready for more
Serial.print(F("\n> "));
}
}
}
Edit 2016-07-11: closed a possible overflow in buffer[].
A rotary encoder is essential in most analog to digital measurements. Everything from volume control to robot movement can be tracked with a good rotatry encoder. Conveniently, everything you need to know is in Wikipedia. This code is a variation on Metsfan’s contribution to the Sparkfun forums. This version avoids unnecessary if statements. SO NERDY.
#define PIN_HIGHBIT (7)
#define PIN_LOWBIT (5)
#define PIN_PWR (3)
#define BAUDRATE (9600)
#define DEBUG (1)
// globals
int state, prevState = 0, count = 0;
/* old state, new state, change (+ means clockwise)
* 0 2 +
* 1 0 +
* 2 3 +
* 3 1 +
* 0 1 -
* 1 3 -
* 2 0 -
* 3 2 -
*/
int encoderStates[4][4] = {
{ 0, -1, 1, 0 },
{ 1, 0, 0, -1 },
{ -1, 0, 0, 1 },
{ 0, 1, -1, 0 },
};
void setup() {
pinMode(PIN_HIGHBIT, INPUT);
pinMode(PIN_LOWBIT, INPUT);
pinMode(PIN_PWR, OUTPUT);
digitalWrite(PIN_PWR, LOW);
digitalWrite(PIN_LOWBIT, HIGH);
digitalWrite(PIN_HIGHBIT, HIGH);
Serial.begin(BAUDRATE);
}
void loop() {
state = (digitalRead(PIN_HIGHBIT) << 1) | digitalRead(PIN_LOWBIT);
count += encoderStates[prevState][state];
#ifdef DEBUG
if (state != prevState) {
Serial.print(state, DEC);
Serial.print(' ');
Serial.print(prevState, DEC);
Serial.print(' ');
Serial.println(count, DEC);
}
#endif
prevState = state;
}
Creating a &;t;select> in PHP can be a mess, if done naively. This should make life a little easier.
$str="<select name='fries_with_that'>
<option value='true'>Yes</option>
<option value='false'>No</option>
</select>";
foreach($customer as $person_id=>$details) {
$fries_with_that=$details['fries_with_that'];
$str=str_replace("value='$fries_with_that'","value='$fries_with_that' selected",$str);
echo str_replace("name='fries_with_that'","name='fries_with_that_$person_id'",$str);
}
