UNO and HC-05 need > 115200 baud

Using Arduino Project Guidance
1

I'm working on a device that captures CANBUS messages and prints them over serial bluetooth. I'm currently using an UNO and HC-05. I'd like to get faster than 115200 baud, ideally >=500k.

I tried setting the Arduino and HC-05 to 230400 which I understand should work with both. This causes my HC-05 to lockup after a few seconds.

After some research it looks my options are:

#1 Switch the crystal on the UNO to 18.432Mhz.

#2 Flash a custom firmware on the HC-05 that supports 250k and 500k

My questions are:

#1 Hardware wise do I just swap the crystals? Software it sounds like I may just have to create a custom board.txt and may have to adjust some timing in my software.

#2 Does anyone have a firmware for the HC-05 that supports 250k and 500k? Or is there different bluetooth module I should be using?

#3 Am I missing something?

2

I'd look for a BT module with a faster bus connection, e.g. SPI instead of serial. The HC-05 may be unable to transmit data so fast at all, this would explain the lockup. What's the speed rating of your BT receiver?

3

Thanks for the tip I'll start googling. My reciever is Nexus 6 Android phone.

4

I think you are on the wrong tram altogether.

I suspect the first thing to do is seriously elaborate on why you need to do this.

I understand it is possible to run an HC-05 at 230400, I don't know why you would, and I assume you would only do it for comms between HC-05s both similarly configured.

https://code.google.com/p/propforth/wiki/LittleRobotBluetoothHC05

The next thing to do is research what is going on at the other end, i.e. what is the speed of the bluetooth module in Android, and can it be reconfigured for a higher speed. I understand the answers are 9600 and no but I think I have had a significant increase in data transfer by reconfiguring at the Arduino end.

And then there is the matter of data speed Bluetooth<>Bluetooth and what you do to ensure that that is enough to make all your work with the serial connections worth while. If it isn't, I understand there isn't anything you can do about it.

If you really have the need for all this speed, you might be better off using WiFi, which I understand is considerably faster than bluetooth 4, which itself is faster than an HC-05. As it is, your Nexus is likely to be running a BT4, and that alone means you are wasting your time with an HC-05.