IBM Model M BT-USB controller conversion kits

apastuszak

24 Aug 2020, 15:08

So, I have to ask...

Any plans to update this to Bluetooth LE available in Bluetooth 4 and 5 to increase battery life? What's the highest capacity battery you can recommend?

mind_prepared

27 Aug 2020, 20:25

apastuszak wrote:
24 Aug 2020, 15:08
So, I have to ask...

Any plans to update this to Bluetooth LE available in Bluetooth 4 and 5 to increase battery life? What's the highest capacity battery you can recommend?
The BT module already supports BT 4.0 BLE and the firmware has been tweaked to minimize power consumption. A 500 mAh battery should last a week or more of constant typing 8h/day, probably longer in an ordinary usage scenario (nobody's typing that much in real life). I've recently exchanged the BT module used for an improved version of the BT chipset which supposedly consumes even less power (I haven't taken any new measurements yet). It's kinda of ironic that while I tried the utmost to minimize power consumption and hence allow using a smaller battery most guys still go for the biggest battery I offer, which is 2000 mAh. A small battery should already give you plenty of mileage, I don't think a big battery is technically necessary.
Note: Even though I haven been ignoring technology for the most part this summer, I did take the time out to tweak the BT module's firmware and add a feature to set the transmission power. So, in theory, you could do some testing in your environment to find the lowest TX value you can get away with and further reduce power consumption. The only problem is that I haven't come up with a good idea how to use the microcontroller that handles the keyboard related tasks and the USB interfacing as a USB to serial bridge so that the value can be changed via UART. Perhaps I will dig deeper into the BT stack's API and find a way to set TX power directly via the BT interface. Perhaps I can add a 'feature request' to the BT HID report desciptor and use that to change values in the firmware, which is how all non-keyboard related data exchange is handled in USB mode (s.a. uploading a layout file, setting a debounce interval, PWM values etc).

The BT chipset the module is based on supports BT 5.0 as well according to the manufacturer. I would just need to upgrade the BT stack from BT 4.0 to BT 5.0 one of these days, perhaps this fall or winter, whenever I get around to it. I have been pretty much ignoring technology during the summer. On a side note, the so-called 'pandemic' doesn't exactly stoke my enthusiasm for adding new features... I currently still cannot ship DHL international economy shipments to US destinations, and the US orders have been the single most significant factor in keeping the project going... (Note: this is my personal opinion based on the situation in Germany, where there has not been a pandemic in the strict sense of the word, the government just keeps ramping up testing to keep everybody scarred, er, I mean scared).

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