Arduino Forum

Using Arduino => General Electronics => Topic started by: JoN on Apr 04, 2011, 10:14 am

Title: how fast is a bluetooth keyboard??
Post by: JoN on Apr 04, 2011, 10:14 am
so, i figured a few people here may have experience using wireless bluetooth keyboards, and was wondering if anyone knows what a typical response time would be for keystroke data to be received by the OS.

why do i ask?  i'm working on a musical instrument design that involves a wireless pedal/button interface.  i need a solution that is very cheap and suitable for use in a stage environment at a distance of about 5-7 meters.  i also need one that has a fast response time to minimise "latency".  ideally i would like keystroke data to have a maximum 1ms transmission time.

is this possible with a bluetooth interface?  i seems quite easy to find relatively cheap wireless BT keyboards these days, so i thought i'd give it a go.

cheers,

jon.
Title: Re: how fast is a bluetooth keyboard??
Post by: PaulS on Apr 04, 2011, 02:31 pm
Typically, bluetooth operates at 115200 baud. That allows you to transmit 11,500 characters per second. I think your requirement is covered.
Title: Re: how fast is a bluetooth keyboard??
Post by: MarkT on Apr 04, 2011, 05:22 pm
Also for a musician to use the repeatability of latency is probably more important that actual latency - for instance the latency of a piano keyboard is probably a lot more than 1ms...
Title: Re: how fast is a bluetooth keyboard??
Post by: cmiyc on Apr 04, 2011, 06:24 pm
Quote
i need a solution that is very cheap and suitable for use in a stage environment at a distance of about 5-7 meters


Is there a clear line of sight?  Even though BT is RF, anything between the devices will significantly reduce the range.  Also, 5-7 meters feels like a long range for a keyboard, a device typically less than 1 meter away from the host.
Title: Re: how fast is a bluetooth keyboard??
Post by: thebigphish on Apr 06, 2011, 11:42 pm
now this is a bit old (http://"http://www.pentest.co.uk/documents/bt_dongle_mod/bt_dongle_mod.html"), but how about slapping an external antenna on the bluetooth module?
Title: Re: how fast is a bluetooth keyboard??
Post by: JoN on Apr 08, 2011, 09:25 am
great... thanks for the ideas guys.

the link for the BT dongle external antenna (thanks bigphish) is slightly corrupt - correct address is:
http://www.pentest.co.uk/documents/bt_dongle_mod/bt_dongle_mod.html
i'm using my laptop's internal BT receiver so not sure i can do that - but actually i think 5-7 meters is an absolute maximum distance for me - normally it should be round 1-2meters...

think i'll have a go hacking a BT keyboard and hopefully post findings here...
Title: Re: how fast is a bluetooth keyboard??
Post by: cmrv on Nov 12, 2014, 12:26 pm
Hi Jon,

I am trying to do something similar, i want to build a piezo drum sending signals from arduino to android, and playing samples on android.

It works, but i am facing a latency problem.

Here is my post:

http://forum.arduino.cc/index.php?topic=277494.0 (http://forum.arduino.cc/index.php?topic=277494.0)

Did you solve the problem?

After many attempts I am about to discard the bluetooth option.
Instead i'm thinking about connecting arduino straight with OTG cable by using this firmware:

http://hackaday.com/2012/06/29/turning-an-arduino-into-a-usb-keyboard/ (http://hackaday.com/2012/06/29/turning-an-arduino-into-a-usb-keyboard/)

Have you tried the option of bluetooth antenna?

Thank you!
Title: Re: how fast is a bluetooth keyboard??
Post by: Shpaget on Nov 12, 2014, 12:49 pm
From my experience, cheap wireless keyboards and mice have just enough range to get from the PC under the desk to the desktop and not any further.