Ground Sensors - Revision history

Dgarzonr at 10:21, 27 February 2020

2020-02-27T10:21:01Z

Dgarzonr at 10:20, 27 February 2020

2020-02-27T10:20:33Z

Dgarzonr at 10:16, 27 February 2020

2020-02-27T10:16:23Z

Manubrambi at 10:31, 19 October 2011

2011-10-19T10:31:40Z

Manubrambi at 10:31, 19 October 2011

2011-10-19T10:31:04Z

Manubrambi: New page: I found at least two ways of using the ground sensors on the e-pucks. This is the one that works best: int ground_tmp[6]; int ground[3]; /* retrieve the values from the sensor...

2011-10-19T10:30:35Z

New page: I found at least two ways of using the ground sensors on the e-pucks. This is the one that works best: int ground_tmp[6]; int ground[3]; /* retrieve the values from the sensor...

New page

I found at least two ways of using the ground sensors on the e-pucks. This is the one that works best:

int ground_tmp[6];
int ground[3];
/* retrieve the values from the sensor */
e_i2cp_init();
e_i2cp_enable();
e_i2cp_read(0xC0, 0);
i = 0;
for(j = 0; j < 6; j++) {
if (j % 2 == 0) ground_tmp[j] = e_i2cp_read(0xC0, j + 1);
else ground_tmp[j] = e_i2cp_read(0xC0, j - 1);
}
e_i2cp_disable();

/* getting the actual values */
ground[0] = ((unsigned int)(ground_tmp[0] & 0xff)) +((unsigned int) ground_tmp[1] << 8) - ground_sensor_zero[id][0];
ground[1] = ((unsigned int)(ground_tmp[2] & 0xff)) +((unsigned int) ground_tmp[3] << 8) - ground_sensor_zero[id][1];
ground[2] = ((unsigned int)(ground_tmp[4] & 0xff)) +((unsigned int) ground_tmp[5] << 8) - ground_sensor_zero[id][2];

This is the function I use to calibrate the sensors (on black paper), store the values at the beginning or in a global variable once and for all:

void GroundSensorCalibrate() {
int i, j;
char tmp[50];
long sensor_tmp[6] = {0};
long sensor[3] = {0};
long delay;

btcomSendString("calibration ground:\n");
for (i=0; i<16; i++) {
// read the values
e_i2cp_init();
e_i2cp_enable();
e_i2cp_read(0xC0, 0);
for(j = 0; j < 6; j++) {
if (j % 2 == 0) sensor_tmp[j] = e_i2cp_read(0xC0, j + 1);
else sensor_tmp[j] = e_i2cp_read(0xC0, j - 1);
}
e_i2cp_disable();

// store the values
sensor[0] += ((unsigned int)(sensor_tmp[0] & 0xff)) +((unsigned int) sensor_tmp[1] << 8);
sensor[1] += ((unsigned int)(sensor_tmp[2] & 0xff)) +((unsigned int) sensor_tmp[3] << 8);
sensor[2] += ((unsigned int)(sensor_tmp[4] & 0xff)) +((unsigned int) sensor_tmp[5] << 8);

// pause
for (delay = 0; delay < 100000; delay++){
__asm__("nop");
}
}
for (i=0; i<3; i++) { ground_sensor_zero[i]=(sensor[i]>>4);
sprintf(tmp,"%d\t%d",i, ground_sensor_zero[i]);
btcomSendString(tmp);
btcomSendString("\n");
}

for (delay = 0; delay < 100000; delay++){
__asm__("nop");
}
}

@@ Line 71: / Line 71: @@
 The I2C bus is configured to work at 400 KHz in the system running on the gumstix overo, thus we need to change the bus speed to 100 KHz in order to communicate with the ground sensor module; the simplest way is to set a kernel parameter in u-boot:
-enter u-boot by pressing any key at boot start
+    enter u-boot by pressing any key at boot start
 type the following command to init the I2C bus 3 to 100 KHz:

@@ Line 71: / Line 71: @@
 The I2C bus is configured to work at 400 KHz in the system running on the gumstix overo, thus we need to change the bus speed to 100 KHz in order to communicate with the ground sensor module; the simplest way is to set a kernel parameter in u-boot:
-    enter u-boot by pressing any key at boot start
+enter u-boot by pressing any key at boot start
-    type the command setenv i2cspeed 3,100; this init the I2C bus 3 to 100 KHz
+type the following command to init the I2C bus 3 to 100 KHz:
 Pay attention that all the peripherals connected to the bus will now work at 100 KHz, thus also the e-puck camera and the LSM330 (accelerometer + gyroscope) present with e-puck HwRev 1.3.

@@ Line 1: / Line 1: @@
 I found at least two ways of using the ground sensors on the e-pucks. This is the one that works best:
@@ Line 61: / Line 64: @@
+   }
+ }

← Older revision		Revision as of 10:31, 19 October 2011
Line 20:		Line 20:


−	This is the function I use to calibrate the sensors (on black paper)~~, store the values at the beginning or in a global variable once and for all~~:	+	This is the function I use to calibrate the sensors (on black paper):

	void GroundSensorCalibrate() {		void GroundSensorCalibrate() {

@@ Line 15: / Line 15: @@
    /* getting the actual values */
-   ground[0] = ((unsigned int)(ground_tmp[0] & 0xff)) +((unsigned int) ground_tmp[1] << 8) - ground_sensor_zero[id][0];
+   ground[0] = ((unsigned int)(ground_tmp[0] & 0xff)) +((unsigned int) ground_tmp[1] << 8) - ground_sensor_zero[0];
-   ground[1] = ((unsigned int)(ground_tmp[2] & 0xff)) +((unsigned int) ground_tmp[3] << 8) - ground_sensor_zero[id][1];
+   ground[1] = ((unsigned int)(ground_tmp[2] & 0xff)) +((unsigned int) ground_tmp[3] << 8) - ground_sensor_zero[1];
-   ground[2] = ((unsigned int)(ground_tmp[4] & 0xff)) +((unsigned int) ground_tmp[5] << 8) - ground_sensor_zero[id][2];
+   ground[2] = ((unsigned int)(ground_tmp[4] & 0xff)) +((unsigned int) ground_tmp[5] << 8) - ground_sensor_zero[2];