I once took apart a Fit Meter, and inside I found an IrDA transceiver module very similar (if not identical) to the [http://www.vishay.com/docs/84672/tfbs4650.pdf|TFBS4650 Infrared Transceiver]. This means for communication, the Fit Meter very likely uses IrDA 9.6 kbit/s to 115.2 kbit/s SIR (but knowing Nintendo, they may have changed it a bit).
IrDA is NOT the same as what a TV remote uses. Unlike with a TV remote, there is no 38khz carrier frequency. Instead, the "frequency" of our signal depends on whether the how fast the data is being sent-- 9.6 kbit/s, 115.2 kbit/s, or somewhere in between.
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If you want to know what the exact waveforms of this communication may look like, check out the [http://www.vishay.com/docs/82513/physical.pdf|IrDA Physical Layer guide] (skip to pages 6 and 7 for a look at the waveforms and how long each individual IR pulse lasts).
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If you want to know what the exact waveforms of this communication may look like, check out the [http://www.vishay.com/docs/82513/physical.pdf|IrDA Physical Layer guide] (skip to pages 6 and 7 for a look at the waveforms).
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'''Edit''': I don't know the speed at which Fit Meter communicates. But '''if''' it communicates at 115.2 kbit/s, then:
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'''Edit''': I don't know the speed at which a Fit Meter communicates. But '''if''' it communicates at 115.2 kbit/s, then:
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* Each individual bit lasts [https://www.google.com/search?q=1+bit+%2F115.2kbps|8.7 microseconds]. (Let's call this our "bit time.")
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But the infrared transmitter is ''not'' turned on for the entire 8.7 microseconds. [http://imgur.com/b2VTMyg.png|Here is an image of an IrDA waveform] (from the guide I linked above) showing how 0's and 1's are sent.
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* To send a "0" bit, the transmitter turns on its infrared light for 3/16th of our bit time. In our case that's 1.63 microseconds.
* To send a "1" bit, the infrared transmitter doesn't turn on at all. It stays dark during the entire bit time.
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(I am myself interested in someday taking a look at Fit Meter IR communication.)
I once took apart a Fit Meter, and inside I found an IrDA transceiver module very similar (if not identical) to the [http://www.vishay.com/docs/84672/tfbs4650.pdf|TFBS4650 Infrared Transceiver]. This means for communication, the Fit Meter very likely uses IrDA 9.6 kbit/s to 115.2 kbit/s SIR (but knowing Nintendo, they may have changed it a bit).
IrDA is NOT the same as what a TV remote uses. Unlike with a TV remote, there is no 38khz carrier frequency. Instead, the "frequency" of our signal depends on whether the how fast the data is being sent-- 9.6 kbit/s, 115.2 kbit/s, or somewhere in between.
If you want to know what the exact waveforms of this communication may look like, check out the [http://www.vishay.com/docs/82513/physical.pdf|IrDA Physical Layer guide] (skip to pages 6 and 7 for a look at the waveforms and how long each individual IR pulse lasts).
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'''Edit''': I don't know the speed at which Fit Meter communicates. But '''if''' it communicates at 115.2 kbit/s, then:
+
* Each individual bit lasts [https://www.google.com/search?q=1+bit+%2F115.2kbps|8.7 microseconds]. (Let's call this our "bit time.")
+
But the infrared transmitter is ''not'' turned on for the entire 8.7 microseconds. [http://imgur.com/b2VTMyg.png|Here is an image of an IrDA waveform] (from the guide I linked above) showing how 0's and 1's are sent.
+
* To send a "0" bit, the transmitter turns on its infrared light for 3/16th of our bit time. In our case that's 1.63 microseconds.
+
* To send a "1" bit, the infrared transmitter doesn't turn on at all. It stays dark during the entire bit time.
I once took apart a Fit Meter, and inside I found an IrDA transceiver module very similar (if not identical) to the [http://www.vishay.com/docs/84672/tfbs4650.pdf|TFBS4650 Infrared Transceiver]. This means for communication, the Fit Meter very likely uses IrDA 9.6 kbit/s to 115.2 kbit/s SIR (but knowing Nintendo, they may have changed it a bit).
IrDA is NOT the same as what a TV remote uses. Unlike with a TV remote, there is no 38khz carrier frequency. Instead, the "frequency" of our signal depends on whether the how fast the data is being sent-- 9.6 kbit/s, 115.2 kbit/s, or somewhere in between.
If you want to know what the exact waveforms of this communication may look like, check out the [http://www.vishay.com/docs/82513/physical.pdf|IrDA Physical Layer guide] (skip to pages 6 and 7 for a look at the waveforms and how long each individual IR pulse lasts).