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Project Help and Ideas » Pedometer Hack

May 10, 2009
by Ethanal
Ethanal's Avatar

I've had a pedometer from a cereal box laying around for years and I finally decided to crack it open to see how it works. With some experimentation, I found all the contacts on the pcb that allow me to externally control when it is reset and when another step is added on the the number on the lcd. I decided to make the pedometer into a stopwatch, but I can't figure out how to induce a virtual step or a virtual press of the reset button. I am thinking I could use transistors, but I don't know how to wire it up. Can anyone help me?

Note: to induce a reset or a step all that has to happen is the respective contacts have to be connected and then disconnected by some means.

May 10, 2009
by wayward
wayward's Avatar

If I understood correctly, you have two contacts on the PCB per switch you want to control, right? If that is correct, then you can try grounding one switch and controlling the other via a pin on the MCU. Keep the pin in high-impedance mode (DDxn low, PORTxn low) for "open" position and switch it to output low (DDxn high, PORTxn low) for "closed" position. This might work, depending on the voltage levels and what resistance the IC on the pedometer will take as "shorted". If this doesn't work, you can tie a C-E of a transistor across the two connectors on the PCB and control the transistor's base with a pin.

May 12, 2009
by Ethanal
Ethanal's Avatar

Thanks. I'll try those ideas.

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