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Test Harness for Pololu QTR Library
Dependencies: PololuQTRSensors mbed
main.cpp
- Committer:
- phillippsm
- Date:
- 2015-08-25
- Revision:
- 0:4a43061bfa34
- Child:
- 1:f3aee4ff2b19
File content as of revision 0:4a43061bfa34:
#include "mbed.h" #include "QTRSensors.h" #define NUM_SENSORS 7 Serial pc(USBTX, USBRX); DigitalOut myled(LED1); // create an object for four QTR-xRC sensors on digital pins 0 and 9, and on analog // inputs 1 and 3 (which are being used as digital inputs 15 and 17 in this case) QTRSensorsAnalog qtra((PinName[]) {A5, A4, A3, A2, A1, A0, PA_3}, NUM_SENSORS, 4, D7); // PA_3, PA_2, PA_10, PB_3, PB_5, PB_4, PB_10 void setup(void); void readSensors(void); void readSensorsPlain(void); int main() { pc.printf("Setup!\r\n"); setup(); pc.printf("Start Loop!\r\n"); while(1) { pc.printf("Read Sensors!\r\n"); readSensorsPlain(); } } void setup() { // optional: wait for some input from the user, such as a button press // then start calibration phase and move the sensors over both // reflectance extremes they will encounter in your application: int i; for (i = 0; i < 50; i++) // make the calibration take about 5 seconds // originally i < 250 { pc.printf("Calibrate Session %d\r\n",i); qtra.calibrate(QTR_EMITTERS_ON); wait_ms(20); } for (i = 0; i < NUM_SENSORS; i++) { pc.printf("Min On %d \r\n", qtra.calibratedMinimumOn[i]); } // optional: signal that the calibration phase is now over and wait for further // input from the user, such as a button press } void readSensors() { unsigned int sensors[NUM_SENSORS]; // get calibrated sensor values returned in the sensors array, along with the line position // position will range from 0 to 2000, with 1000 corresponding to the line over the middle // sensor. int position = qtra.readLine(sensors); // if all three sensors see very low reflectance, take some appropriate action for this // situation. if (sensors[0] > 750 && sensors[1] > 750 && sensors[2] > 750) { // do something. Maybe this means we're at the edge of a course or about to fall off // a table, in which case, we might want to stop moving, back up, and turn around. pc.printf("do something. Maybe this means we're at the edge of a course or about to fall off a table, in which case, we might want to stop moving, back up, and turn around."); //return; } // compute our "error" from the line position. We will make it so that the error is zero // when the middle sensor is over the line, because this is our goal. Error will range from // -1000 to +1000. If we have sensor 0 on the left and sensor 2 on the right, a reading of // -1000 means that we see the line on the left and a reading of +1000 means we see the // line on the right. int error = position - 1000; int leftMotorSpeed = 200; int rightMotorSpeed = 200; if (error < -500) // the line is on the left leftMotorSpeed = 20; // turn left if (error > 500) // the line is on the right rightMotorSpeed = 20; // turn right pc.printf("Left Motor %d, Right Motor %d\r\n", leftMotorSpeed, rightMotorSpeed); myled = 1; // LED is ON wait_ms(leftMotorSpeed); // 200 ms myled = 0; // LED is OFF wait(rightMotorSpeed); // 1 sec // set motor speeds using the two motor speed variables above } void readSensorsPlain() { unsigned int sensors[NUM_SENSORS]; // get calibrated sensor values returned in the sensors array, along with the line position // position will range from 0 to 2000, with 1000 corresponding to the line over the middle // sensor. pc.printf("before\r\n"); qtra.readCalibrated(sensors, QTR_EMITTERS_ON); pc.printf("after\r\n"); for (unsigned int i = 0; i < NUM_SENSORS; i++) { pc.printf("Sensor Value[%d] %d Min %d Max %d \r\n", i, sensors[i], qtra.calibratedMinimumOn[i], qtra.calibratedMaximumOn[i]); } // set motor speeds using the two motor speed variables above }