![]() ![]() For example, if you use a sixteen-bit counter for your angles and you declare there to be 65,536 counts per revolution, you’ll never need to do “mod 360”. If you scale your values such that they map directly to the magnitude range of the underlying storage, everything will wrap automatically. Moreover, the properties of fixed-point numbers become very useful when the value being counted has a natural modulus, for example angles (360 degrees) or time of day (24 hours or 24.6597222 hours). No need for floating point there just have an integer counting the number of cents! This is fixed point, and you’ll never have to worry about $0.03 looking like $0.029999999999999999. Decide your precision requirements up front for example, you might want to count money accurately to the nearest cent. But it is certainly convenient for the programmer, up until they start having mysterious accuracy problems due to unpredictable epsilons. Since your counters aren’t all modulo-some-power-of-two, the effective bit count won’t be an integer.įloating point is overused and overrated for tasks in which the range of numerical range is narrowly defined. This is basically the same thing as giving yourself a few extra bits of fixed-point precision. Posted in clock hacks Tagged Martian time, TI Chronos Post navigation Still, an awesome build if your job description includes driving a rover across the Martian plains. He plans on adding a few bells and whistles such as being able to display both Earth and Mars time. The build only took five hours in front of his computer, and he doesn’t consider this to be a finished product. ![]() There’s one small glitch with that plan: the timer in the Chronos wristwatch can’t deal with floating point numbers, meaning had to settle for incrementing the number of seconds ever 33,668 or 33,669 clock cycles. After a bit of math, found using a value of 33,669 would mean his Martian time watch would only lose about 2 seconds a day, a minute after 78 Martian Sols, or 8.57 Martian minutes after one Martian year. This meant changing the seconds every 33,668.833 clock cycles, instead of the Earth-oriented 32,768 clock cycles. In its stock configuration, the Chronos takes a 32.768khz clock signal, counts out clock pulses, and increments the number of seconds every time a counter reaches 32,768.īecause a Martian Sol is 24 hours, 39 minutes and 35 seconds of Earth time, needed to program the seconds display to change every 1.027 Earth seconds. ![]() The build began by taking the default firmware for the Texas Instruments EZ430 Chronos wristwatch. Instead of a master watchmaker selling the slowest wristwatch ever for hundreds of dollars, staying on Curiosity time is a simple matter of reprogramming a $50 wrist-mounted computer. Now we have incredibly inexpensive, fully programmable TI Chronos watch, used by to make a wristwatch set to Martian solar time. After much cajoling, a watchmaker by the name of was convinced to create a mechanical watch that lost 39 minutes per day, giving the team responsible for driving Spirit and Opportunity across the Martian desert these last eight years a temporal connection to the task at hand. Because a Martian day lasts 24 hours, 39 minutes, rover team members would have to report to work 39 minutes later than the previous day. Mars24 time clock drivers#After the twin rovers landed, the rover drivers would have to live on Mars time. The timestamp is only as accurate as the clock in the camera, and it may be completely wrong.Eight long years ago, when the Martian rovers Spirit and Opportunity were steaming towards our dusty neighbor, JPL systems engineers and were stuck trying to solve a very strange problem. If the file has been modified from its original state, some details such as the timestamp may not fully reflect those of the original file. Mars24 time clock software#This file contains additional information such as Exif metadata which may have been added by the digital camera, scanner, or software program used to create or digitize it.
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