[time-nuts] new tdc from Texas

Poul-Henning Kamp phk at phk.freebsd.dk
Wed Mar 4 06:13:47 EST 2015

In message <BLU170-W50577ECF0B24FA2BCEFC50CE1E0 at phx.gbl>, Mark Sims writes:

>Sparkfun is selling a board (around $15) based on the STM VL6180
>chip that measures distance based upon time-of-flight of pulses
>from an on chip (or at least in-package) VCSEL IR laser.   Claims
>to have a range of 0 .. maybe 30 cm.   Unfortunately it doesn't
>look like you can directly access the time interval measurement
>portion of the chip.

It doesn't measure time interval, it measures frequency.

These devices contain an oscillator where the flight of the light pulse
is the delay element, then measure the resulting frequency.

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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