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11

That'll be because you're creating an audio signal - an audio signal is AC coupled, and will always want to drift towards ground since ground is what it is centred around. An android phone's headphone socket cannot create reliable digital waveforms since it's an analog output. You should instead choose something that is suited to what you want, instead of ...


11

None of the smartphones today have dedicated GPS chips in them, they only have a GPS capability that stems from byproduct features of the modem chips. That's not true. GPS functionality in phones is done either with a dedicated chip, or with a dedicated GPS receiver within a System-On-Chip (which is effectively the same as having a dedicated chip). ...


10

The signal from the headphone jack is most likely AC-coupled. The easy way to fix this is to add a diode from each signal line to ground: anode of both diodes to ground, cathode of each diode to your signal line. The diodes act as a clamp and allow the signal to NOT go lower than about -0.6V. The remainder of the signal amplitude is above ground (...


7

There is no such thing like "datasheet for phone". Phone is consumer electronics. Consumer doesn't have to know all these things. All you can/should get from manufacturer is manual (that usually says: "use original battery charger"). I would not recommend trying to power phone from 12V even if you are sure that there is BQ24190 chip, because you don't know ...


6

The Google Play page for the app you linked has a section for microphone support which includes a link to an instructable for a circuit: ***** Microphone SUPPORT ****** The second option is the microphone input to the android device. This can be used to attach a scope lead to the jack socket. More information can be found at the following website. ...


5

This is a pretty good question. The USB Type-C specifications gives a vague answer. In Section 2.3.3, it describes two functions, Dual-Role-Power, and Dual-Role-Data, which are established upon examining the status of one of CC lines on both sides of a link. The bottom of Page 23 reads: Once initially established, the Source supplies VBUS and behaves ...


4

There isn't really a standard, it depends on exactly what headphone amplifier the phone uses. The closest thing is the -10dBV (.9VPP) consumer line level output, but I doubt most phones have the actual output level calibrated to that standard. It's more than likely that they tested it by plugging the phone into a couple of AV receivers and found that it got "...


4

A digital pin, when used as input, offers very little input resistance. Note that this holds for DC current. Since you want to scale \$12V\$ to be \$5V\$: $$5V=12V\frac{R_1}{R_1+R_2}$$ that leads to \$R_1=0.417(R_1+R_2)\$. There still is a degree of freedom, that is the total divider resistance. The factors that can help you to choose it are: Your \$12V\$ ...


4

From FT232R datasheet: TEST: Puts the device into IC test mode. Must be tied to GND for normal operation, otherwise the device will appear to fail. In your schematic the TEST-pin is floating


4

To solve this problem you can instead modify the encoding so the sum of 1 and 0 bits actually sent over the wire converges to equal and the number of consecutive 1s and 0s is minimal. This means sending some extra bits over the wire but it will remove the DC component that the audio hardware can't handle. This means using a constant weight encoding or Paired ...


3

If your Android device supports USB OTG(On the go) you might be able to use the Arduino as a standard USB serial device connected to the android. My phone can do this I just needed a cheap cable to convert the micro USB to a USB A port. I used the ArduinoCommander App to test out the connection.


3

You would need some hardware added to the Uno which supports USB host mode, yes. This could be in the form of a USB host shield or some other USB host module (typically with its own on-board microcontroller) Yes, definitely. Typically a board which incorporates USB host mode, would also be supported by its tried and tested libraries for implementing the host ...


3

A few problems that I can see are: The JY-MCU appears to be a 3.3V device and you have it connected to VIN which is 5V. Try connecting to the 3V3 line although be aware this will be available only when running from USB power because it's supplied by the FTDI USB chip. Before doing that though I've found references to it not having 5V tolerant serial lines ...


3

(Expanding on Kurt E Clothier's comment ...) As often, the answer should be "it depends", in this case on the nature of the signal that's being transmitted via the coax cable. If the original signal is an analog type signal this type of transmission would involve several steps: Conversion of the analog signal into digital byte stream using an analog-to-...


3

Four cells will put you over the nominal voltage of a single Li-Ion cell and it might be OK considering they will use a switch-down converter. However that is not guaranteed, it may damage the phone, it may have over-voltage protection that will prevent it starting up or worst case may have some form of clamps that will damage your batteries and/or cause a ...


3

It is not unusual to have a USB device draw its power from a source other than the USB connection; such a configuration is called "self-powered" and the device's datasheet will give the exact schematic, components, and sometimes even PCB layout to make such a thing possible. It is resistances placed on the D+ and D- lines that announce presence rather than ...


3

You indicated Bluetooth doesn't satisfy your requirements, and I agree. But that's classic Bluetooth. Are you familiar with BLE (Bluetooth Low Energy, part of the Bluetooth 4.0 spec)? The maximum range is anywhere from 50m to 450m, depending on the module used. (That last figure is not a typo, here is the BLE121LR -- LR for long-range. And it still runs ...


3

I haven't trawled through all your code, but one immediate mistake I see is this: uint8_t msg[3]={0x0}; ... digitalWrite(LED4, msg[3]==0x1 ? HIGH : LOW); You allocate an array of 3 bytes (slices 0..2) and then reference slice 3, which is the 4th byte of a 3-byte array.


3

The white wire is (99.5 % certainly) a temperature measuring thermistor connection that helps your system not destroy the battery and in the process create smouldering ruin. If your battery gets too hot the system will stop charging - if it 'knows' the battery is too hot. If not ... . Batteries without this 3rd connection are relatively rare and it may ...


3

It depends what kind of data you want to send. The Android will support any bluetooth profile listed on the developers site for the respective versions. I found some info here. Most common profiles will be supported. Then you just need a module that supports the profile you wish to use. If you want to implement a UART type connection, then you need the SPP (...


3

No. USB uses complex digital signaling on those data lines, that requires some digital processing power to work at all. Using an USB enabled microcontroller to translate the output of the sensor would be one of the simplest solutions, but it needs its own program.


3

Try to power your tablet through 5V USB port without the battery installed. The tablet has battery management, replacing battery with voltage from regulator may flag the error causing shutdown.


3

USB / USB OTG doesn't give you much of an option here – the device never powers the host, so you can't charge your tablet while it's the host to an OTG device – at least as long as the tablet behaves standards-compliant (and I'd argue doing that here would be a very good idea, because drawing power from a device sounds like a very bad idea if the device ...


2

While there isn't a simple solution to the stated requirement, here is one approach: Purchase, in retail, a new cheap Android phone that meets the specifications. Often the "old cheap" phones will be more expensive than new models, and will also suffer from spares (batteries!) sourcing. Also purchase an Android Accessory Development Kit (ADK), either the ...


2

I know this is an old thread, but it might still deserve some attention... Bluetooth on Android is mainly used for connecting to wireless headsets. Wireless headsets are slave (not master) devices. This means you'll be able to connect to your slave-only cheap-o Bluetooth module. In fact, I have one of those modules ($6 on Ebay), and I just successfully ...


2

I want to develop such hardware (like square) which can be used to capture fingerprints through the headphone jack. If it possible? Yes this is possible . The IR sensor or any other sensor will take analog data and you will need to process the data and send it over 3.5 jack to Iphone or Android Regarding help on the device check this out http://web.eecs....


2

No. By default you can't do this, due to different principles of work and hardware chips. As I mentioned earlier my answer on Physics.SE clarify this. About other possibilities, there were some projects, that provide external abilities, like Touchtag, which was on a market since 2008 to 2012. I think you can use same idea and then redirect data to audio ...


2

Most of the comments focus on the more common problem of removing/ignoring the noise so that the other sound can be extracted. You want to do the other thing around: detect air-blow sounds, rejecting all other sound. First, your zero crossing method is not going to be very useful for this. Air-blow is close to pink noise in signal shape, with some "tint" to ...


2

USB doesn't have the notion of TX and RX lines, it's not a UART. The data lines are D+ and D- used for bidirectional differential signaling. The VBUS line (which you refer to as Vcc) is essential for detection the presence of the host (IOIO in this case), so what you're suggesting will not work. The best you can do is use the current limiting trimmer that's ...


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