Tuesday, August 21, 2012

RCArduino passed 40,000 Hits Today

RCArduino has been visited 40,000 times since I bought my first Arduino and started the blog in January of this year.

So whats coming in the future ?

In no particular order-

1) An update to the serial servo library that gives the option of an additional ten servos so that now we can have 20 servos using only four pins and two 30 cent chips.
Twice the power of this - http://rcarduino.blogspot.com/2012/08/arduino-serial-servos.html Ten servos on two pins -


2) A new servo library that does not require external components but includes some novel features which will be useful in a range of applications - its currently on the desk next to me generating a servo signal from almost every single pin of my Arduino - thats right 18 Servos one from every nonessential digital pin and one from every single analog pin - thats not one of its advantages, just part of the testing process before I release it.

3)  More on the RCArduino Lap Timer build along. We have run two rounds of a lap record contest using the system at the Pro RC Track in Dubai. One of the questions everyone asks is can they have their own personal timer to take home and can they be paired with two different cars so that you can run against each other using individual boxes. This is something I am working to address, so stay tuned.

Some laps from the first contest run using the RCArduino Lap Timer - one in a box, one on breadboard both running the code published on this blog.

4) I have made a breakthrough in the design of a fast lightweight library for reading RC Receivers, in the meantime there are two optimizations I will release for the previous approach provided here - http://rcarduino.blogspot.com/2012/04/how-to-read-multiple-rc-channels-draft.html - Look out for an update.

Finally if you have used the code or techniques from the RCArduino blog to build something interesting, let me know and I will post it.

Stay Tuned

Duane B

RCArduino

4 comments:

  1. Congratulations on 40,000 hits! I'm looking forward to the news, I've been following your posts for a while, looking to give my RC some traction and stability control.

    I've got my arduino reading three receiver channels and outputting to two servos as a straight pass through, while writing the channel value changes to the serial port. I want to be able to read motor RPM and wheel speeds, and I've read over your page on using IR to sense wheel speeds. I don't know how much space you have on the M chassis, but on my TT01 I've got enough room around the gearbox joints to put the sensors inboard of the dogbones so the wiring doesn't have to move with the suspension, and it can be hard mounted to the chassis.

    What I was wondering, since you've got more experience with the Arduino, Do you think that reading the motor RPM directly from the brushless sensor wire would affect the performance of other software running on the microcontroller? My motor is a 4000kV running on a 2s LiPo, which means it can theoretically reach almost 30,000 RPM. which means the hall effect sensors on the motor (http://www.rcgroups.com/forums/showthread.php?t=1196594) could pulse at up to 500 times a second. My other alternative would be to put a sensor like the wheel speed sensors on the spur gear or driveshaft, which would trigger less often, but requires more parts.

    Anyway, keep it up! People are reading :)

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  2. Hi, Your right about the space and wiring, the hardware and software for measuring the wheel speeds is simple, but fixing the wiring and sensors in the m-chassis is proving very difficult. In the TT01 you can get the motor speed from the drive shaft, if you have a look in this post http://rcarduino.blogspot.com/2012/03/reading-from-rc-reveiver-do-you-need.html there are some very small surface mount sensors that will read the shaft speed, the one pictured is supplied with Spectrum TX/RX specifically to measure motor speed. When I took a look at the performance of the servo library here - 600 interrupts per second took up only one percent of the Arduino processing power so its possible to respond to that volume of interrupts and still do useful work, but if you can reduce the volume of interrupts by reading the drive shaft you will get less glitches. The glitches happen when two, three, four or more interrupts all need to be serviced at one time, what happens is your output servo pulse ends up stretched as its the lowest priority pulse and has to wait for all of the others to finish. Duane B

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    Replies
    1. Thanks for the reply. Getting the speed with the fewest interrupts would be the best, and you're right, other than gear reduction, there is no difference between drive shaft and motor speed, since there is no center diff. Sounds good!

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