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I'm assembling a bluetooth speaker as DIY project. i'm stuck with bluetooth receiver module which have inbuilt push button (hold for 5 sec) to start/stop the bluetooth receiver. I want to ignore that switch and want to start the device directly when connecting the module to the battery. I looking for only one switch to power on everything. Please guide me.

Note: This is my first DIY electronics project and I'm new to electronics.

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  • \$\begingroup\$ I am pretty sure there is some configuration setting for that on the device. \$\endgroup\$ – Eugene Sh. Jul 9 '18 at 17:08
  • \$\begingroup\$ I'm pretty sure there isn't. The Bluetooth (note capitalisation) device will have some sort of micro-controller and the hold for 5 s will be coded into that. \$\endgroup\$ – Transistor Jul 9 '18 at 17:11
  • \$\begingroup\$ I didn't find anything. It's a bluetooth audio receiver for car. \$\endgroup\$ – DeebashVFX Jul 9 '18 at 17:11
  • \$\begingroup\$ Well, until you provide us with the device information - we can only make guesses. \$\endgroup\$ – Eugene Sh. Jul 9 '18 at 17:15
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    \$\begingroup\$ The problem here is that you are trying to make a fixed function consumer product (even if you rip it out of the case, that's still what it is) do something different than what it was designed to. \$\endgroup\$ – Chris Stratton Jul 9 '18 at 20:07
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Pairing is the Problem

There are two issues when "turning on" a Bluetooth device. One is the traditional power. The second is pairing. Pairing tells the device to look for other Bluetooth devices and connect to them. The first time with a particular device pair there is usually some sort of confirmation required. Without this step, multiple people with cellphones, wireless speakers, etc. would all get jumbled together - which would not be secure and also cause a lot of confusion.

Typically a device will remember the last device it paired with, so that when you turn it on it will automatically find & connect to the same device if it is in range. But to avoid the process happening unnecessarily, the device will typically require a long-press. That allows the same button to be used for other functions. For example, my Bluetooth headset requires a long-press for on (including pairing to an existing device) and uses a regular short-press for answering/disconnecting calls.

It is certainly possible to have a device which has a more traditional power switch with the pairing function handled differently. But you typically won't find that on a $6.99 receiver. The alternative, as suggested by another answer, is to build/program a device to simulate a 5-second long-press.

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  • \$\begingroup\$ It's definitely going to be a problem. I'll try to create pulse as mentioned in other answer. \$\endgroup\$ – DeebashVFX Jul 9 '18 at 18:22
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Find the switch. Connect two wires across it. A simple Monostable circuit can generate a 5 s pulse. You can connect that to switch and there you go. As soon as there is power, the pulse will be generated simulating the long press behaviour.

If you cut the power, I assume it is off.

Challenges:

  1. Switch is pulling the pin of an IC (MCU or other circuitry), so it Can be pulled up or pulled down by default. You have to monitor it first.

  2. The other circuitry might be operating at a voltage and might not like different voltage. So better to use a 1:2 MUX type IC rather than directly driving via transistor or another 555 IC.

  3. If there are any other function for the switch?

  4. Your pulse generator circuitry should be powered from something.. Voltage source?

Update 1

Example of one shot pulse mode with 555 timer in one sho monostable mode.

an Example partial circuit: A resistor of 100 kohm and 47uF capacitor will give a short pulse of ~5s. The switch in the diagram can be shorted to ground via 100 ohm resistor.
a BJT can be used as inverter if needed depending on polarity of the pulse expected for the IC you are planning to drive.

enter image description here

I would use some thing like this which is a simple SPDT switch to short the switch pins.
enter image description here

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  • \$\begingroup\$ Thanks a lot. I got an idea from your answer. But i have to study well about Monostable circuit and other challenges that you have mentioned. Switch has no other function other than switching on/off and pairing. I have main battery power supply for entire Bluetooth speaker system. So i'll use that to generate 5 sec pulse as you mentioned. \$\endgroup\$ – DeebashVFX Jul 9 '18 at 17:57
  • \$\begingroup\$ "As soon as there is power, the pulse will be generated simulating the long press behaviour." This needs clarification. Many simple monostable circuits do not return to original state as long as input present. \$\endgroup\$ – Maple Jul 9 '18 at 18:21
  • \$\begingroup\$ @Maple I suggested a few ideas.. Once we have more observation on the button, state, behavior for long press ( and holding the button in pressed condition long after) and other use cases of button, I cam make my answer more precise. Input to the monostable circuit, power options for that are open still. As soon as the problem is clear, my answer will be. \$\endgroup\$ – Umar Jul 9 '18 at 18:40
  • \$\begingroup\$ I'm not sure there is anything unclear in the OP question and comments. The battery voltage is an input signal. When it is applied the button on device should be shorted for 5 seconds and then released. As simple as that. Am I missing something? \$\endgroup\$ – Maple Jul 9 '18 at 18:55
  • \$\begingroup\$ Much better. Now, if only you can show OP the circuit that is triggered by applying power to it, without any buttons, it would be perfect answer :) Hint: the application of power is a beginning of a pulse by itself. All you need is shut it down in 5 sec. \$\endgroup\$ – Maple Jul 9 '18 at 23:49

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