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Author Topic: how fast is a bluetooth keyboard??  (Read 627 times)
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jon
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« on: April 04, 2011, 03:14:09 am »
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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.
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PaulS
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« Reply #1 on: April 04, 2011, 07:31:22 am »
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Typically, bluetooth operates at 115200 baud. That allows you to transmit 11,500 characters per second. I think your requirement is covered.
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MarkT
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« Reply #2 on: April 04, 2011, 10:22:54 am »
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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...
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James C4S
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« Reply #3 on: April 04, 2011, 11:24:35 am »
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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.
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thebigphish
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« Reply #4 on: April 06, 2011, 04:42:00 pm »
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now this is a bit old, but how about slapping an external antenna on the bluetooth module?
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jon
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« Reply #5 on: April 08, 2011, 02:25:00 am »
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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...
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