Aukey Touch Control RGB Lamp Upgrade

Since all the ICs have had their markings removed, I'm not sure what the chips actually are. But, a quick check of the footprint of some 8-pin PICs verifies that I can swap the unknown chip on the PCB out for one that I can program.

I did a parameter search for an 8 pin device with PWM and an EEPROM, since I wanted to use hardware PWM and be able to save settings. Interestingly, the PIC16F18313 was the only candidate.

https://www.microchip.com/wwwproducts/en/PIC16F18313

This PIC has only two PWMs, so I can't use it with all four LED drivers. I'll just power the white LED driver with this hardware PWM, and bit bang the remaining three 2 kHz RGB drivers.

A really nice feature of this modern PIC is the preferal pin select, which allows me to programmatically assign functions to pins. This way, I can assign the hardware PWM output to match the existing footprint. The other pins will just be GPIO, so nothing special needed there.

First thing to do is take it apart.

• Carefully remove the four screws in the base under the anti-skid rubbery circle

Now that it's apart, probe around and figure out what the chips do and what signals exist at which pins.

• Pin 5 of U2 has a 20 kHz PWM signal on it. As the brightness changes, it cycles through 20, 60, and 100 % duty cycle. When the LED is to be off, the pin is held low.
  • The white LED driver appears to be a switch-mode constant current design. The details of the design are not important here, since we know how to control it.
• Pins 2, 3, and 7 have a 2 kHz PWM signal, with duty cycle correlating to the following:
  • Pin 2: Blue PWM
  • Pin 3: Red PWM
  • Pin 7: Green PWM
  • It is interesting to see that these LEDs use current limiting resistors, with PWM being used as more of a voltage source here. Again, not going to dig in to it because I know how to control it.
• Pin 6 changes when the power LED changes. For my version, I won't be using this. In fact, I may even disable this entirely, since I'm not sure why a lamp needs an LED to indicate that it is on.
• Pin 4 is pulled low when the shroud is touched, so is the input from the cap sense interface chip, U5. Again, the implementation doesn't matter, all we care about is the signal.
• Pin 1 and 8 are power and gnd, respectively.

Sometimes I find my old Galaxy Note useful!