pictographer
Well-known member
Trying to embed a Teensy LC in a Logitech K400r wireless keyboard that we use to control a media PC running Ubuntu. The keyboard controls the computer just fine, but I thought it would be nice to be able to control the Samsung TV as well. I prototyped this with a portable battery and the Teensy with the IRremote library works beautifully.
The keyboard takes two AA batteries. I didn't notice before I started carving things up that the batteries are wired in parallel. The highest voltage available from the keyboard controller is 2.2V. The Kinetis KL26 has a minimum Vdd of 1.71V, so maybe? On the Welcome to Teensy-LC card, Vin is spec'd from 3.7 to 5.5 volts. I don't need USB Serial during normal operation.
Is there a simple way to run the Teensy LC on 2.2V?
Adding a boost converter would be challenging due to space limitations inside the keyboard case, but might be possible, especially if there are any boost converters that don't require too many external components.
Adding a 3V coin cell could work, though I'd need to find a way to change the battery without disassembling the keyboard.
Would it make sense to use diodes to have the batteries both in series and in parallel simultaneously?
Would it help to power the Teensy only when a momentary contact button was pressed? Maybe some supercapitor circuit could power the Teensy just long enough to turn on/off the TV.
If all else fails, I could remove the Teensy from the keyboard and attach it to the PC. I'd arrange a hot key on the PC to trigger the Teensy to send a command to the TV. The keyboard would have a few embarrassing holes, but that's what I get for failing do my homework before cutting.
The keyboard takes two AA batteries. I didn't notice before I started carving things up that the batteries are wired in parallel. The highest voltage available from the keyboard controller is 2.2V. The Kinetis KL26 has a minimum Vdd of 1.71V, so maybe? On the Welcome to Teensy-LC card, Vin is spec'd from 3.7 to 5.5 volts. I don't need USB Serial during normal operation.
Is there a simple way to run the Teensy LC on 2.2V?
Adding a boost converter would be challenging due to space limitations inside the keyboard case, but might be possible, especially if there are any boost converters that don't require too many external components.
Adding a 3V coin cell could work, though I'd need to find a way to change the battery without disassembling the keyboard.
Would it make sense to use diodes to have the batteries both in series and in parallel simultaneously?
Would it help to power the Teensy only when a momentary contact button was pressed? Maybe some supercapitor circuit could power the Teensy just long enough to turn on/off the TV.
If all else fails, I could remove the Teensy from the keyboard and attach it to the PC. I'd arrange a hot key on the PC to trigger the Teensy to send a command to the TV. The keyboard would have a few embarrassing holes, but that's what I get for failing do my homework before cutting.