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bluetooth custom keyboard

Hello,

I would like to know if I can get some indications on the overall design of a new custom bluetooth keyboard product using the CC2540 IC. Do I need another microcontroller like an MSP430?, it seems like the CC2540 could handle it by itself, Also, is there any reference or example implementation of something similar?.

Thanks!.

5 Replies

  • Guru 12430 points

    Hi Manuel,

    are you from Spain? The CC2540 contains an 8051 microcontroller so it should be enough for you.

    I think there is een a Human Interface Device (HID) design in the Texas INstruments BLE stack, so you are lucky :)

    Bye!



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  • In reply to kazola:

    Hi,

    Yea I'm from Spain :). Sadly I realized that I can't use CC2540 since it doesn't support bt < 4.0 / BLE and my host device is bt 2.1. I was looking into MSP430 + CC2560-PAN1325 but it isn't low power (as far as I know) and I don't know if those could be powered by a coin cell. Since it is a keyboard and It doesn't require continuous transmission it looks like that could save a lot of power by using low power modes, but who knows.

    The CC2540 looks neat and perfect for this application but I would have to drop support for older devices without BT 4.

    Thanks.

  • Guru 12430 points

    In reply to manu.2ka8:

    I'm in Barcelona.

    It is difficult to use classical BT with a 230mAh coin battery :(

    Perhaps your best shot would be employing a class 3 transceiver (1mW - 0dBm) but even this way...



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  • In reply to kazola:

    Are you totally sure that it isn't possible? I mean, considering the keyboard application and using low power modes, also the fact that the emitting antenna is going to be millimetres away from the receiving one, perhaps the CC2560 can be adjusted to emit using less power.

  • Guru 12430 points

    In reply to manu.2ka8:

    I'm not saying it is not possible!

    I'm saying the battery of the module will not last for long but it really depends strongly on your application.

    The module you say is class 2. Its output power is +12dBm (15.8mW). Considering 3V... around 5mA and this would last for... 230mA / 5mAh = around 45 hours in the most PESSIMISTIC case (always transmitting).



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