Sparkfun: IR Receiver Breakout Board - Revision history

Yoder: Updated grading comments

2012-10-17T21:06:22Z

Updated grading comments

Millerap at 13:37, 5 October 2012

2012-10-05T13:37:52Z

Millerap at 13:17, 5 October 2012

2012-10-05T13:17:03Z

Millerap: /* Testing and Results */

2012-10-04T15:27:20Z

‎Testing and Results

Millerap: /* Sending a Signal */

2012-10-04T15:22:34Z

‎Sending a Signal

Millerap: /* Sending a Signal */

2012-10-04T15:19:11Z

‎Sending a Signal

Millerap: /* Sending a Signal */

2012-10-04T15:12:13Z

‎Sending a Signal

Millerap: /* Background Information */

2012-10-04T14:56:25Z

‎Background Information

Millerap at 14:52, 4 October 2012

2012-10-04T14:52:13Z

Millerap: /* Sending a Signal */

2012-10-04T14:49:55Z

‎Sending a Signal

@@ Line 3: / Line 3: @@
 <pre style="color:red">
-Overview:  0, In your Background section, give details on what the device is.
+Overview: 2
-What is it able to do? Show a picture of the device that shows what pins it has.
+Wiring:   2
-In 'Sending a Signal', show a diagram with the IR emitter sending a signal to your device.
+Code:     1, Could stil use some step by step instructions.
-Describe at a high level what you are doing, then go into the details of how you do it.
+git:      2
-Wiring:   0, Give a specific example of how to wire it.  What pins go where?
+Demo:     2
-Which bone header are you using?  P8, P9?
+Total:    9/10
-Code:     1, Give step by step instructions so it's easy for someone else to reproduce it.
+Comments:  Thanks for all the work you put into this.  It turned into a bigger project than most.
-git:    2
-Demo:     0
-Total:    3/10
-Comments:  More details are needed.  I think someone else in the class would have trouble
-reproducing what you have done.  It looks like your code transmits only.  Have you had any luck
-with receiving on the bone?
-−
-Generally functions aren't defined in .h files.  Could you move the functions to a BoneHeader.c file and create
 </pre>

← Older revision		Revision as of 13:37, 5 October 2012
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	These following diagram shows how to wire the BeagleBone to reproduce my testing procedure.		These following diagram shows how to wire the BeagleBone to reproduce my testing procedure.

		+	[[File:Wiring Diagram for IR Sensor.png\|400px\| Wiring Diagram for use with the C code provided below]]

← Older revision		Revision as of 13:17, 5 October 2012
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	using UART or the PRU (Programmable Real-Time Unit) would prove much more efficient.		using UART or the PRU (Programmable Real-Time Unit) would prove much more efficient.
		+
		+	== '''Wiring''' ==
		+
		+	These following diagram shows how to wire the BeagleBone to reproduce my testing procedure.
		+
		+

	== '''Testing and Results''' ==		== '''Testing and Results''' ==

@@ Line 68: / Line 68: @@
 '''All measurements and tests were performed using a 5V source'''
-To test the operation of this device, I wrote a test script for the BeagleBone that repeatedly transmits an ascii 'c' char to the IR Receiver. I used a bitrate of 1kHz to transmit. With an 8-bit char, that gives a character transmit rate of 125Hz. While that is not particularly fast this rate allowed for accurate testing of the rise time for this device, which as can be seen in the figure below was measured on an oscilloscope to be 225us. By the measured rise time value, the maximum bit rate is around 4.4kHz.
+To test the operation of this device, I wrote a test script for the BeagleBone that repeatedly transmits an ascii 'c' char to the IR Receiver. My code used all of the setup described above to setup a 38kHz square wave on ehrpwm1:0. I used a bitrate of 1kHz to transmit, meaning that every 1ms I toggled the PWM either on or off depending on the next bit of the 'c' I was transmitting. This involved using a usleep(1000) to wait 1ms between toggles. With an 8-bit char, that gives a character transmit rate of 125Hz (1kHz/8bits = 125Hz). While that is not particularly fast this rate allowed for accurate testing of the rise time for this device, which as can be seen in the figure below was measured on an oscilloscope to be 225us. By the measured rise time value, the maximum bit rate is around 4.4kHz.
 The code used to perform this testing is available on github.com. Use the following to download it.

@@ Line 46: / Line 46: @@
 Next, the same sort of experiment was performed using a BeagleBone. The BeagleBone's built in PWM outputs can be set to act the same as the 38kHz square wave created by the function generator. How to set this up will be detailed below. The same IR LED was then hooked up to the BeagleBone's PWM output, and the PWM was set to run with a frequency of 38kHz and duty cycle of 50%. This also caused the output on the oscilloscope to read a zero when turned on.
-To set up and use the PWM, I used '''ehrpwm1:0''', which is located on pin 6 of mux '''gpmc_a2'''. '''gpmc_a2''' is located on pin 14 of the BeagleBone, and has pin 7 of the mux enabled by default. To change the enabled pin of any '''gpmc_a2''' you must change the value stored in the file /sys/kernel/debug/omap_mux/gpmc_a2 on the BeagleBone from 7 to 6. The directory /sys/kernel/debug/omap_mux contains all of the muxes on the BeagleBone, and any one of them can be changed by writing into their respective files.
+To set up and use the PWM, I used '''ehrpwm1:0''', which is located on pin 6 of mux '''gpmc_a2'''. '''gpmc_a2''' is located on pin 14 of the BeagleBone, and has pin 7 of the mux enabled by default. To change the enabled pin of '''gpmc_a2''' you must change the value stored in the file /sys/kernel/debug/omap_mux/gpmc_a2 on the BeagleBone from 7 to 6. The directory /sys/kernel/debug/omap_mux contains all of the muxes on the BeagleBone, and any one of them can be changed by writing into their respective files.
 Once '''ehrpwm1:0''' is enabled on pin 14, its frequency and duty cycle must be set. By writing 38000 into /sys/class/pwm/ehrpwm1:0/duty_freq, we can set the frequency to 38kHz, and by writing 50 into /sys/class/pwm/ehrpwm1:0/duty_cycle, we can set the duty cycle to 50%. This will result in a 38kHz squarewave on the output when /sys/class/pwm/ehrpwm1:0/run is set to 1.

@@ Line 42: / Line 42: @@
 == '''Sending a Signal''' ==
-The TSOP85338 operates with a carrier frequency of 38kHz. That is, when the IR sensor is receiving an IR signal that is being modulated at 38kHz it outputs a logic 0.
+The TSOP85338 operates with a carrier frequency of 38kHz. That is, when the IR sensor is receiving an IR signal that is being modulated at 38kHz it outputs a logic 0. To test this operation, I hooked up an IR LED to a function generator set to a 38kHz square wave. The function generator created the carrier frequency required to the receiver to recognize it. I hooked up the VDD pin of the IR Receiver to a 5 volt source limited to 100 mA, and i hooked up the output pin to an oscilloscope. When the function generator's output was turned on, the IR Receiver's output went low, and when it was shut off again, the output value went high.
 Using the BeagleBone to send a message to the TSOP85338 can be done using one of its PWM outputs. To perform testing of these attributes, '''ehrpwm1:0''' can be used. By setting the '''duty_freq''' to 38000 and '''duty_percent''' to 50, it is possible to toggle an IR LED which if received by the sensor will output a logic 0. If the TSOP85338 is not receiving this modulated IR signal, it outputs a logic 1.

← Older revision		Revision as of 14:56, 4 October 2012
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	The Picture below the one on the left shows the bottom of the IR Receiver. The Receiver needs an external VDD source to power it. This VDD can be varied from 2.5V-5.5V as seen above. The middle pin is the output, and it can be read by a device such as a BeagleBone. Additionally the circuit diagram of the TSOP85338 is available below.		The Picture below the one on the left shows the bottom of the IR Receiver. The Receiver needs an external VDD source to power it. This VDD can be varied from 2.5V-5.5V as seen above. The middle pin is the output, and it can be read by a device such as a BeagleBone. Additionally the circuit diagram of the TSOP85338 is available below.
		+
		+

	[[File:Pinout Diagram TSOP38553.jpg\|200px\|left\| Bottom side view of the physical IR Receiver Breakout Board]]		[[File:Pinout Diagram TSOP38553.jpg\|200px\|left\| Bottom side view of the physical IR Receiver Breakout Board]]

@@ Line 32: / Line 32: @@
 The picture on the left shows the physical device. This IR Receiver receives an modulated IR signal and reacts accordingly. It has filters built in to eliminate interference from ambient light, and it will not react to just any IR signal sent to it. This device needs an IR signal that is modulated as a 38kHz square wave. When it receives a modulated IR signal, it outputs a low signal. Otherwise, it outputs a high signal.
-The Picture below the one on the left shows the bottom of the IR Receiver. The Receiver needs an external VDD source to power it. This VDD can be varied from 2.5V-5.5V as seen above. The middle pin is the output, and it can be read by a device such as a BeagleBone. Additionally the circuit diagram of the TSOP38553 is available below.
+The Picture below the one on the left shows the bottom of the IR Receiver. The Receiver needs an external VDD source to power it. This VDD can be varied from 2.5V-5.5V as seen above. The middle pin is the output, and it can be read by a device such as a BeagleBone. Additionally the circuit diagram of the TSOP85338 is available below.
 [[File:Pinout Diagram TSOP38553.jpg|200px|left| Bottom side view of the physical IR Receiver Breakout Board]]
@@ Line 40: / Line 40: @@
 == '''Sending a Signal''' ==
-The TSOP85338 operates with a carrier frequency of 38kHz. That is, when the IR sensor is receiving an IR signal that is being modulated at 38kHz it outputs a logic 0. On a high level, This
+The TSOP85338 operates with a carrier frequency of 38kHz. That is, when the IR sensor is receiving an IR signal that is being modulated at 38kHz it outputs a logic 0.
 Using the BeagleBone to send a message to the TSOP85338 can be done using one of its PWM outputs. To perform testing of these attributes, '''ehrpwm1:0''' can be used. By setting the '''duty_freq''' to 38000 and '''duty_percent''' to 50, it is possible to toggle an IR LED which if received by the sensor will output a logic 0. If the TSOP85338 is not receiving this modulated IR signal, it outputs a logic 1.