Wireless and Bluetooth features. What is it that you want to see?

[MOZ]

As part of my TS65 project, I'm looking to add wireless functionality to the board.

This thread is more general, to find out what features users would like to see in a Bluetooth wireless keyboard. Since my project is open-source, once I have the firmware support and electronic design completed, the wireless features should be easily made into an adapter board that can be used with existing keyboards.

I need to get answers to some simple questions and you are more than welcome to add more.

First, some background:
1. USB can supply 5V at 500mA once enumerated as a keyboard device, truly it can supply 2.5W.
2. Most barebone keyboards use around 40-50mA at 5V, which is 200mW - 250mW.
3. Bluetooth Low Energy (BLE - BT 4.0) uses around 25mA at 3.3V, which is 100mW (Taking into consideration of 5V to 3.3V stepdown efficiency)
4. Rest of the 2.15W (~430mA @ 5V) is available for the other bells and whistles as well as charging a battery if required.
5. Rechargeable AA batteries are about 1900mAh @ 1.2V (Typical) - Using two in series which is quite common for such applications, we can draw about 4.5W. Using a barebones keyboard with BLE and no backlighting/RGB we can get about 12 hours considering the efficiency of step-up conversion.
6. Li-ion/Li-Po batteries suitable for a portable keyboard would be about 2100mAh @ 3.7V - 7.77W, which should give around 21 hours of battery time on the the barebones BLE keyboard.

NOTE: I'm a bit lost as to how existing wireless boards last so long on battery. I would really appreciate an answer on this.


Questions:
1. What kind of battery would you like to see in a keyboard?
  -- AA
  -- Li-Ion/Li-Po
  -- Doesn't matter
  -- Other, please specify

2. Would you like to have the board the ability to charge over USB?
  -- Yes
  -- No
  -- Doesn't matter

3. What would be the max acceptable charge time?
  -- 1 hour
  -- 2 hour
  -- 4 hours
  -- Over night charge (Around 8 )
  -- Other, please specify

4. Due to limitations of USB a max of only 400mA can be used for charging a battery, this would mean a charge time of around 4 hours. Would you like the ability to charge via a dedicated charger (Such as one supplied with your phone)?
  -- Yes
  -- No
  -- Doesn't matter

5. If your answer to 4 is yes, what would be your preferred method for charging using a dedicated charger?
  -- Same connector used to connect to computer
  -- Dedicated secondary USB port (micro or mini)
  -- Barrel-style wall wort connector
  -- Qi, wireless charging
  -- Doesn't matter
  -- Other, please specify


6. What is the minimum acceptable battery time?
  -- 12 hours
  -- 24 hours
  -- 1 week
  -- 2 weeks
  -- 1 month
  -- Other, please specify

TIA

[cy384]

For the sake of comparison, I'll mention my custom bluetooth keyboard; I recently added bluetooth to my Atreus by chopping up a Handheld Scientific adapter.  My main complaints would probably be cost, inconvenience of desoldering parts, size, and having to design my own brackets etc. for the pcb and battery.  It charges a Li-Ion battery via USB but does not pass the connection through (so, bluetooth only).  In terms of the end result, I'm quite happy with it, it charges in a few hours, and lasts 10-ish hours of active use.  As it can charge while being used, it's not exceptionally inconvenient to run out of power.

Regarding what I'd like to see from an adapter/board to embed in future projects:

> What kind of battery
Li-Ion/LiPo

>Charge over USB?
Absolutely yes.

>Max acceptable charge time?
Overnight

>Dedicated charger
No way, don't want more cables and adapters to keep track of.

>Wireless charging?
Qi/wireless charging would be kinda cool, I'd consider it.

Overall, I'd be interested in either a bluetooth/charging module to add to a keyboard with some other controller, or a single module integrating an atmega32u4 with the bluetooth and charging stuff.

[pomk]

The trick to having good battery life is just using power optimized components. For example the nRF51822 (bt4.0) chip can run on 200 ľA average current at around 6 key presses per second. The 200 ľA figure is from Raytac. With 2 x AAA batteries it amounts to some silly number like 260 days of continuous typing, not taking battery degradation into account.

[Zorox]

1. Li-Ion/LiPo
2. Yes
3. 4h would be nice
4. No, no more cabels for a wireless build pls
5. Wireless charging, with charge pad as removable case
6. 24h, incase I have to go to a party afterwork and get hangover

[ndlu2]

I've thought about modding my keyboard to be wireless and I was considering the Adafruit Bluetooth LE board which sells for about $30. It includes bluetooth, can be powered with usb or a lipo battery, and includes a charging circuit.


1. What kind of battery would you like to see in a keyboard?
  -- Doesn't matter

2. Would you like to have the board the ability to charge over USB?
  -- Yes [Qi charging is fine too]

3. What would be the max acceptable charge time?
  -- Over night charge (Around 8 ) [prefer 8 hour battery life if its this long]

4. Due to limitations of USB a max of only 400mA can be used for charging a battery, this would mean a charge time of around 4 hours. Would you like the ability to charge via a dedicated charger (Such as one supplied with your phone)?
  -- Doesn't matter

5. If your answer to 4 is yes, what would be your preferred method for charging using a dedicated charger?
  -- Qi, wireless charging


6. What is the minimum acceptable battery time?
  -- 12 hours