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From what I researched the e-reader's motherboard contains three unused serial ports that can be connected from gps modules to bluetooth chips.

enter image description here

Close up Picture of the U2713 pin out

U2713 PIN OUT CLOSEUP

The article that gives instructions states that its hardware does not include a logic level to RS-232 voltage level translator("transceiver") so one must be added for RS-232 communications.

The board was apparently designed to use a connector similar to Digikey part number A99963TR-ND.

I don't know if a bluetooth chip has anything to do with the aforementioned sentence. Because this tutorial is meant for a gps module.

Based on this pin out and the board's design; if possible, what kind of bluetooth would I use preferably without wires to minimize hassle in soldering?

This is the site that gives the instructions.

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    \$\begingroup\$ um, what are you going to do with that bluetooth module? Because that thing will not "magically" start talking to some new hardware that you attach. Someone has to write the firmware that makes it talk. \$\endgroup\$ – Marcus Müller Jan 8 '19 at 17:59
  • \$\begingroup\$ I already got the firmware set up. I'm planning on doing this to my rooted nook so that I can use a bluetooth keyboard and mouse. To make it easier to use linux distros ontop of the android system. \$\endgroup\$ – Travis Wells Jan 8 '19 at 18:02
  • \$\begingroup\$ Yes, I am running Linux distros ontop of the modified system quite well. \$\endgroup\$ – Travis Wells Jan 8 '19 at 18:04
  • \$\begingroup\$ youtube.com/watch?v=ThDSK2mAMsg \$\endgroup\$ – Travis Wells Jan 8 '19 at 18:05
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    \$\begingroup\$ The footprint looks like a connector's footprint. You can measure the pitch between the pads, and find a suitable wire to board connector. \$\endgroup\$ – Lior Bilia Jan 8 '19 at 18:22
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You can use any uart capable device that has a logic level serial port and operates on 3.3V.

Only three pins of the U2713 connector are needed. (4 are needed if you need to supply 3.3V to your serial device.)

It would be close to a miracle if some bluetooth module had a connector that mated directly with the pinout of U2713.

So, you are pretty much going to have to break out the soldering iron and attach wires to your Nook and your bluetooth device.

Use fine wire, and put a spot of hot glue or epoxy on the (grouped) wires to hold them in place. That is, bundle the wires, and glue the bundle down.

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The hard part is getting a Bluetooth IC that talks UART. Most of these devices are attached via USB.

However, mouser does list some modules that have an UART interface. You'll want to check which of these have an upstream Linux driver.

Generally, Bluetooth transceivers talk to their host using a protocol called HCI; that's pretty standardized.

However, the way features are set up over that protocol depends on the actual device, so be sure to get something that you don't have to spend nights on writing kernel and bluez support for.

But then you'd only have the IC and no antenna, no microwave-engineered PCB transmission lines, no power supply, so, either you design these on a PCB, or:

get a Bluetooth module with UART. Again, verify that the chip on that has upstream Linux kernel support. Especially, a lot of these modules (e.g. the Cypress based ones, if I remember correctly) do have Linux support, but only via USB. It's probably no big deal getting Linux to recognize a HCI device on a serial line (for bluez: btattach -B /dev/ttyACM0 or so, whatever your serial port is), but the details of talking to hardware are often uglier than thought at first.

I'll respectfully point out that if you can, finding a USB bus on the device, adding a hub chip and wiring devices to that might be easier at first.

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