Sparkfun: HMC5883L Magnetometer - Revision history

Duganje: /* Communicating with the HMC5883L Using the Shell */

2012-11-06T17:35:18Z

‎Communicating with the HMC5883L Using the Shell

Duganje: /* Communicating with the HMC5883L Using the Shell */

2012-11-06T17:34:38Z

‎Communicating with the HMC5883L Using the Shell

Duganje: /* Graphical Display using Node.js */

2012-11-06T17:31:18Z

‎Graphical Display using Node.js

Duganje: /* C Example Code */

2012-10-22T19:54:31Z

‎C Example Code

Yoder: Updated grading comments

2012-10-17T21:01:20Z

Updated grading comments

Duganje: /* Communicating with the HMC5883L Using the Shell */

2012-10-14T23:15:37Z

‎Communicating with the HMC5883L Using the Shell

Duganje: /* Using C */

2012-10-14T18:18:37Z

‎Using C

Duganje: /* Example Code */

2012-10-14T18:12:48Z

‎Example Code

Duganje: /* Communicating with the HMC5883L Using the Shell */

2012-10-14T18:12:03Z

‎Communicating with the HMC5883L Using the Shell

Duganje: /* Connecting to the Bone */

2012-10-14T18:03:19Z

‎Connecting to the Bone

@@ Line 107: / Line 107: @@
 beagle$ '''i2cget -y 3 0x1e 4'''
 '''Note:''' '''i2cget -y 3 0x1e 3 w''' gets both bytes of the X-Axis, but the bytes are flipped so the less significant byte is first.
 By default the magnetometer takes a single sample and enters idle mode.The lowest two bits of the mode register (register 02) control the measurement mode. Setting these to 0x01 will cause the device to take one measurement and then enter idle mode again. Setting to 0x00 should cause the device to enter continuous measurement mode where measurements are taken periodically at a sampling rate set by configuration register A (register 00),

← Older revision		Revision as of 17:34, 6 November 2012
Line 107:		Line 107:

	beagle$ '''i2cget -y 3 0x1e 4'''		beagle$ '''i2cget -y 3 0x1e 4'''
		+
		+	'''Note:''' '''i2cget -y 3 0x1e 3 w''' gets both bytes of the X-Axis, but the bytes are flipped so the less significant byte is first.

	will get the two halves of the 16-bit signed measurement along the +x axis.		will get the two halves of the 16-bit signed measurement along the +x axis.

@@ Line 125: / Line 125: @@
 ==Graphical Display using Node.js==
-Starting with the [https://github.com/MarkAYoder/BeagleBoard-exercises/tree/master/node.js/realtime node.js code] provided as a starting point for [http://elinux.org/EBC_Mini_Project_04 Miniproject04], I wrote a [https://github.com/duganje/ECE497_duganje/tree/master/MiniProject04 program] created a web-based graphical display of the magnetometer measurements. The program requires the nodejs package to be installed
+Starting with the [https://github.com/MarkAYoder/BeagleBoard-exercises/tree/master/node.js/realtime node.js code] provided as a starting point for [http://elinux.org/EBC_Mini_Project_04 Miniproject04], I wrote a [https://github.com/duganje/ECE497_duganje/tree/master/MiniProject04 program] that creates a web-based graphical display of the magnetometer measurements. The program requires the nodejs package to be installed
   beagle$ '''opkg update'''
   beagle$ '''opkg install nodejs'''

← Older revision		Revision as of 19:54, 22 October 2012
Line 122:		Line 122:

	the [http://elinux.org/EBC_Exercise_12_I2C I2C code] from exercise 12 can be used to communicate with the magnetometer. I modified myi2cget.c from this exercise to create a [https://github.com/duganje/ECE497_duganje/tree/master/MiniProject02 program] that puts the magnetometer into continuous measurement mode and reads and prints the values measured along each axis in an infinite loop.		the [http://elinux.org/EBC_Exercise_12_I2C I2C code] from exercise 12 can be used to communicate with the magnetometer. I modified myi2cget.c from this exercise to create a [https://github.com/duganje/ECE497_duganje/tree/master/MiniProject02 program] that puts the magnetometer into continuous measurement mode and reads and prints the values measured along each axis in an infinite loop.
		+
		+	==Graphical Display using Node.js==
		+
		+	Starting with the [https://github.com/MarkAYoder/BeagleBoard-exercises/tree/master/node.js/realtime node.js code] provided as a starting point for [http://elinux.org/EBC_Mini_Project_04 Miniproject04], I wrote a [https://github.com/duganje/ECE497_duganje/tree/master/MiniProject04 program] created a web-based graphical display of the magnetometer measurements. The program requires the nodejs package to be installed
		+	beagle$ '''opkg update'''
		+	beagle$ '''opkg install nodejs'''
		+
		+	To run the code on the Bone:
		+	beagle$ '''node buttonBox.js'''
		+
		+	Then point you web browser to '''bone:8081''' where bone is the ip address of you Bone
		+	This is what the display should look like
		+	[[File:Nodejs.jpg]]

@@ Line 3: / Line 3: @@
 <pre style="color:red">
-Overview:  1, show a picture of the device that shows what pins it has.
+Overview:  2
-Wiring:   1, Give a diagram that shows how the pull up resistors are used.
+Wiring:    2, a bit fuzzy, but I can figure it out.
-Code:     0,  i2cget can get 16bit values.  Check out the 'w' option.
+Code:      1,  i2cget can get 16bit values.  Check out the 'w' option.
-git:    0 put in git
+git:       2
-Demo:     0
+Demo:      2
-Total:    2/10
+Total:     9/10
 Comments:  More details are needed.  I think someone else in the class would have trouble
 reproducing what you have done.   I'd like to see a C code version working.  I'm not sure

@@ Line 113: / Line 113: @@
 beagle$ '''i2cset -y 3 0x1e 2 1'''
- writes a 1 to register 02 and this will cause a single measurement to be taken.
+writes a 1 to register 02 and this will cause a single measurement to be taken.
 The new values for each axis can be read from registers 03-08 as shown above. By default the measurements correspond to 1090 LSB/Gauss, but this can be changed by modifying the gain in Configuration Register B.

@@ Line 119: / Line 119: @@
 Note: reading a value of 0xF000 (-4096) in a data output register indicates an overflow or underflow error in the ADC or a math error.
-==Using C==
+==C Example Code==
-the [http://elinux.org/EBC_Exercise_12_I2C I2C code] from exercise 12 should work for the magnetometer, but it produces an error trying to read from or write to the device. This is probably because the magnetometer I2C operates at 400Khz and the bone uses 100kHz, so anything other than the simple shell commands produces corrupted data due to timing errors.
+the [http://elinux.org/EBC_Exercise_12_I2C I2C code] from exercise 12 can be used to communicate with the magnetometer. I modified myi2cget.c from this exercise to create a [https://github.com/duganje/ECE497_duganje/tree/master/MiniProject02 program] that puts the magnetometer into continuous measurement mode and reads and prints the values measured along each axis in an infinite loop.

← Older revision		Revision as of 18:12, 14 October 2012
Line 122:		Line 122:

	the [http://elinux.org/EBC_Exercise_12_I2C I2C code] from exercise 12 should work for the magnetometer, but it produces an error trying to read from or write to the device. This is probably because the magnetometer I2C operates at 400Khz and the bone uses 100kHz, so anything other than the simple shell commands produces corrupted data due to timing errors.		the [http://elinux.org/EBC_Exercise_12_I2C I2C code] from exercise 12 should work for the magnetometer, but it produces an error trying to read from or write to the device. This is probably because the magnetometer I2C operates at 400Khz and the bone uses 100kHz, so anything other than the simple shell commands produces corrupted data due to timing errors.
−
−	~~==Example Code==~~
−	~~The following shell script sets the magnetometer to continuous measurement mode and then reads and displays the sensor values every half seconds assuming the sensor is connected to I2C bus 3.~~
−
−	~~# read the sensor value of a magnetometer~~
−
−	~~cleanup() { # Release the GPIO port~~
−	~~echo ""~~
−	~~exit~~
−	}
−
−	~~trap cleanup SIGINT # call cleanup on Ctrl-C~~
−
−	~~XM=0~~
−	~~XL=0~~
−	~~YM=0~~
−	~~YL=0~~
−	~~ZM=0~~
−	~~ZL=0~~
−
−	~~#set to continuous measurement mode~~
−	~~i2cset -y 3 0x1e 2 0~~
−
−	~~# Read forever~~
−
−	~~while [ "1" = "1" ]; do~~
−
−	~~#read sensor values~~
−	~~XM=`i2cget -y 3 0x1e 3`~~
−	~~XL=`i2cget -y 3 0x1e 4`~~
−	~~ZM=`i2cget -y 3 0x1e 5`~~
−	~~ZL=`i2cget -y 3 0x1e 6`~~
−	~~YM=`i2cget -y 3 0x1e 7`~~
−	~~YL=`i2cget -y 3 0x1e 8`~~
−
−	~~echo -n -e "X_MSB=${XM} X_LSB=${XL} Y_MSB=${YM} Y_LSB=${YL} Z_MSB=${ZM} Z_LSB=${ZL}\r"~~
−	~~# sleep for a while~~
−	~~sleep 0.5~~
−	~~done~~
−
−
−	~~cleanup # call the cleanup routine~~

@@ Line 102: / Line 102: @@
 |}
-The sensor values for each axis are 16-bit and are stored across 2 registers each.
+The sensor values for each axis are 16-bit and are stored across 2 registers each assuming the devise is connected to I2C bus 3.
 beagle$ '''i2cget -y 3 0x1e 3'''
@@ Line 110: / Line 110: @@
 will get the two halves of the 16-bit signed measurement along the +x axis.
-By default the magnetometer takes a single sample and enters idle mode.The lowest two bits of the mode register control the measurement mode. Setting these to 0x01 will cause the device to take one measurement and then enter idle mode again. Setting to 0x00 should cause the device to enter continuous measurement mode,
+By default the magnetometer takes a single sample and enters idle mode.The lowest two bits of the mode register (register 02) control the measurement mode. Setting these to 0x01 will cause the device to take one measurement and then enter idle mode again. Setting to 0x00 should cause the device to enter continuous measurement mode where measurements are taken periodically at a sampling rate set by configuration register A (register 00),
 beagle$ '''i2cset -y 3 0x1e 2 1'''
-will cause a single measurement to be taken.
+ writes a 1 to register 02 and this will cause a single measurement to be taken.
 The new values for each axis can be read from registers 03-08 as shown above. By default the measurements correspond to 1090 LSB/Gauss, but this can be changed by modifying the gain in Configuration Register B.

@@ Line 25: / Line 25: @@
 The Beagle Bone can be connected to the magnetometer via the I2C bus. Ground and Vcc on the breakout board should be connected to pins 1 and 2 respectively on the bone's P9 header, and the SCL and SDA pins should be connected to one of the I2C pairs on the bone. I used I2C bus 3 (pin 19 on header P9 connected to SCL and pin 20 on P9 to SDA) because it is configured out of reset. 4.7k&Omega; pullup resistors should be connected between SCL and Vcc and between SDA and Vcc.
-[[File:Miniproject2.jpg]]
+[[File:Miniproject2.JPG]]
 The address of the magnetometer can be found by using the i2cdetect command from the shell. I get: