After some close inspection of the Philips Sonicare toothbrushes we have at Ionic Industries for testing, not only do the basic Li-ion battery models (FlexCare, EasyClean) have a lot in common with the most expensive model (DiamondClean) in terms of the physical actuator that vibrates the brush-head but they also have the same microcontroller on board to run the brush – a PIC 16F726 from Microchip (sorry for the blurry photo!)
The main clue for hackability comes in the form of these conveniently labelled test-points on the PCB near the switch:
The pads made available are labelled Tx, Rx, Vdd, Vpp and two Ground points. Wow, serial communication lines and possibly a way to supply the higher programming voltage required (Vpp) for burning new code into the PIC. This got us thinking – could you re-program a cheap single-mode toothbrush like the EasyClean to behave like the expensive 5-mode DiamondClean?
Well, we just need to read through the 300 page datasheet for the PIC 16F726 to find out! Philips will surely have used the code protection features of these chips so that we can’t just read their code straight off and modify it. It could be a fun project for someone to write their own code and program it into their toothbrush. Motor that plays a tune anyone? Disco light feature? Add a bluetooth chip and build your own SmartGuide equivalent to display your brushing progress or write a smartphone app? Oh the possibilities…
If any students are looking for a domestic appliance final-year degree project working with these Microchip PIC microcontrollers then let us know – it could make for a great dissertation project!