Connecting smartphone via bluethooth to electronic devices

[Tostuk]

Hi all
I would like to start my own company and I have a little idea running. I need to have a device connected to a phone via bluethooth and it needs to recieve info from the phone but I don't know much about electronics and I am left with a question. What should be the "brains" of the device? I was originally thinking to use an ATtiny or an ATmega microcontroller since those are the only two that I know basically.

Also, I didn't quite know which forum this question should be on, so sorry if it's the wrong one.
Thanks

 

[andre_luis]

Re: Question for a circuit

There are microcontrollers or modules with bluethooth capability with no need of any additional shields, running as standalone CPUs; therefore I would not consider ATtiny/ATmega for this. With regard to alternatives to this, I am a bit suspicious to recommend the solution more suited to your case since I have my preference, but I have been using ESP8266 and ESP32 for some time, and this device, besides being very small, also has the capacity to communicate, along with bluethooth, via Wifi as well, which is another feature often available on smartphones.

 

[FvM]

"Receive info from the phone" is a bit vague. Do you consider to write an android app that uses specific Bluetooth protocols or are you relying on the services already built into your phone?


ATmega would need an external Bluetooth transceiver like HC-05, ESP32 or other Bluetooth enabled processors have all resources on board.

 

[c_mitra]

Re: Question for a circuit

along with bluethooth, via Wifi as well, which is another feature often available on smartphones...

WIFI is more "open-source" than bluetooth and BT has a very small range compared to WIFI.

For a smartphone everything looks like a file and you can transfer information just like a file. I have not done that but it is simple in principle.

For the frontend (that is the most important part visually) you need to write a compatible application. And you need to write some software for the other end too.

 

[Tostuk]

The problem with wifi is that the phone needs to be connected to the device for hours at a time and thus it wouldn't be able to connect to the internet for a while.

 

[andre_luis]

The problem with wifi is that the phone needs to be connected to the device for hours at a time and thus it wouldn't be able to connect to the internet for a while.

From the mobile application side, there is no impediment to connect to many devices if the Wifi network of the device is configured as "station mode", that is, if instead of device creating its own network, rather they are both connected - smartphone and device - to a wireless router with its own network.

 

[Tostuk]

From the mobile application side, there is no impediment to connect to many devices if the Wifi network of the device is configured as "station mode", that is, if instead of device creating its own network, rather they are both connected - smartphone and device - to a wireless router with its own network.

That is true but I believe that it may become a problem, for example I don't have my home wifi network where I need the device to be at. But wifi is a good alternative and I'll keep it in mind.

I was looking into the ESP32 microcontroller and I thought that I should give it a try. Now I would want to stay away from using dev boards and I'd like to integrate the chip (ESP-WROOM-32) into my PCB design, but I'm not sure how to do it, I mean I'm pretty sure that I can't just slap it on there. I looked through the datasheet but it didn't help me a lot though. The microcontroller doesn't need to do much, it just needs to connect to the phone and activate a mosfet basically. So any tips on how I should integrate it would be awesome.

Also, big thanks for helping me out!

 

[andre_luis]

Now I would want to stay away from using dev boards and I'd like to integrate the chip (ESP-WROOM-32) into my PCB design, but I'm not sure how to do it

To get introduced on this platform, I would recommend buying an ESP32-based NodeMCU as there is integrated on board the ESP-WROOM-32 module along with an USB programmer, all built-in; as for the firmware language, the Arduino IDE is a nice choice for simple and even more complex tasks.

The microcontroller doesn't need to do much, it just needs to connect to the phone and activate a mosfet basically

Since you will use few pins, prefer those that are not shared with any other internal module feature and/or don't have any sort of constraints, and according to my reviews, seems like being these ones, but I'm not totally sure whether there are more restrictions or not:

• IO0 => Pull-Up (I can use eg. as a button input: Normal Open for GND)
• IO1 => Programmer's TX - RESERVED !!!
• IO2 => Pull-Down (I can use eg. as button input: Normal Open for 3V3
• IO3 => Programmer's RX - RESERVED !!!
• IO4
• IO5 => Pull-Up (I can use as a button input: Normal Open for GND)
• IO6 => Internal Flash - RESERVED !!!
• IO7 => Internal flash - RESERVED !!!
• IO8 => Internal Flash - RESERVED !!!
• IO9 => Internal Flash - RESERVED !!!
• IO10 => Internal Flash - RESERVED !!!
• IO11 => Internal Flash - RESERVED !!!
• IO12
• IO13 => Programmer's RTS (Reserved?)
• IO14 => Programmer's CTS (Reserved?)
• IO15
• IO16
• I017
• IO18
• IO19
• IO20 => Does not exists at Datasheet (deprecated at some of the last revisions)
• IO21
• IO22
• IO23 => Connected to IO20 (Reserved?)
• IO25
• I026
• IO27
• IO32
• IO33
• IO34 => Input only
• IO35 => Input only
• IO36 => Input only
• IO37 => Not accessible externally to the module (Reserved?)
• IO38 => Not accessible externally to the module (Reserved?)
• IO39 => Input only