Feb 2009
Speed Climbing Timing - Part 4 Touch Pad Construction
02/25/2009 19:20 Filed in: IR Sensors | Speed timing
Synopsis: In Part 4, get a sneak peak of the mechanical design and construction of the sensor for stopping the clock at the top of a speed climbing route, the hand sensor. A video outlines the thinking behind the design and how it can work well for the climber and the routesetter to mount the sensor on the climbing wall.
Some of the critical requirements for this sensor are:
Robustness - it has to be able to take a direct, forceful hit by a climber’s hand. Often a climber will launch for the finish and smack the finish switch. It’s this behavior that has destroyed more speed climbing timing systems than any thing else. So, this touch pad has to be robust even though there’s no mechanical switch. A corollary to the robustness is safety. It has to be robust, but it needs to be safe for a climber to hit, even if he or she hits it very hard.
Assuming this IR light based sensor works well, climbers will quickly figure out they don’t need to practically destroy the sensor in order to stop the clock. The finish technique and behavior for finishing a speed climbing route will change to more finesse as a result.
Inexpensive - Another major requirement is the touch pad should be inexpensive to build. This mechanical and mounting solution uses easily attainable and inexpensive components from your local home improvement store. The sensors themselves are about $10 each (GP2Y0A21YK from Sparkfun), so there are $20 of sensors and about $10 of other materials for a total per-pad cost of about $30. For a 2-lane system, there are 2 touch pads for hands (one for each lane’s finish) and two base sensors for feet to detect false starts, so the system cost can get quite high if the per-pad cost isn’t kept low.
Easy to Mount - Finally, it had to be lightweight and easy to mount. This sensor, because it is installed at the top of the speed climbing route, needs to be ported up a ladder by a routesetter and mounted to the climbing wall. The solution presented is both lightweight and extremely robust and can be mounted with the standard climbing hold hardware - a 3/8” bolt. The bolt can be tightened as much as desired to keep the pad from moving on the wall without any damage to the sensor mounting hardware whatsoever.
Video below the break.... Read More...
Some of the critical requirements for this sensor are:
Robustness - it has to be able to take a direct, forceful hit by a climber’s hand. Often a climber will launch for the finish and smack the finish switch. It’s this behavior that has destroyed more speed climbing timing systems than any thing else. So, this touch pad has to be robust even though there’s no mechanical switch. A corollary to the robustness is safety. It has to be robust, but it needs to be safe for a climber to hit, even if he or she hits it very hard.
Assuming this IR light based sensor works well, climbers will quickly figure out they don’t need to practically destroy the sensor in order to stop the clock. The finish technique and behavior for finishing a speed climbing route will change to more finesse as a result.
Inexpensive - Another major requirement is the touch pad should be inexpensive to build. This mechanical and mounting solution uses easily attainable and inexpensive components from your local home improvement store. The sensors themselves are about $10 each (GP2Y0A21YK from Sparkfun), so there are $20 of sensors and about $10 of other materials for a total per-pad cost of about $30. For a 2-lane system, there are 2 touch pads for hands (one for each lane’s finish) and two base sensors for feet to detect false starts, so the system cost can get quite high if the per-pad cost isn’t kept low.
Easy to Mount - Finally, it had to be lightweight and easy to mount. This sensor, because it is installed at the top of the speed climbing route, needs to be ported up a ladder by a routesetter and mounted to the climbing wall. The solution presented is both lightweight and extremely robust and can be mounted with the standard climbing hold hardware - a 3/8” bolt. The bolt can be tightened as much as desired to keep the pad from moving on the wall without any damage to the sensor mounting hardware whatsoever.
Video below the break.... Read More...
Speed Climbing Timing - Part 3 Integration
Synopsis: This is a video to show the initial integration of the IR sensors with the stop switch interrupt of the microcontroller. There’s more work to do as you will see. Later in the article are a couple videos which show the system working after an EMI issue caused spurious interrupts.
The basic integration of the IR sensors with the AVR is:
Video below the break....
Read More...
The basic integration of the IR sensors with the AVR is:
- IR Sensors have a high frequency component and the overall wave goes from about .8v to 2.5-3V.
- I take the IR signal into a low-pass filter to clean up the signal and remove the high frequency components
- That signal goes through a non-inverting comparator and amps the signal to the rail when the IR beam is reflected with a hand
- The output of the comparator goes to a hex inverter (74LS14) schmitt trigger
- The output of the schmitt trigger goes to the interrupt of the ATMega128.
Video below the break....
Read More...
Speed Climbing Timing - Part 2 Controller
In Speed Climbing Timing Part 1, I introduced the touchless sensor concepts of a speed climbing timing system. In this part, I’ll demonstrate the basic controller and the timing functions as well as the display driver.
The display is based on a Maxim 7219 LED multiplexor. The controller is an Atmel AVR ATMega128. I’ve developed the Max7219 driver code and the basic timer to deal with a two-lane speed climber competition.
Read More...
The display is based on a Maxim 7219 LED multiplexor. The controller is an Atmel AVR ATMega128. I’ve developed the Max7219 driver code and the basic timer to deal with a two-lane speed climber competition.
Read More...
Speed Climbing Timing - Part 1 Sensors
02/19/2009 13:34 Filed in: IR Sensors | Speed timing
Most of my kids climb competitively and do an event called speed climbing. The name pretty much says what it’s about, but in general, 2 climbers go head-to-head on 2 25-50’ routes. After a climb is finished, they switch routes and climb again. The addition of the times of the two routes is the total time for the climber.
A problem that has plagued the event is the speed timing systems used are very unreliable. Most of these systems rely on some type of mechanical switch for the foot pedal and the top hand sensor to stop the clock at the finish, the top of the climber’s “lane”. Because the systems malfunction so frequently and can ruin the flow of the event and drastically extend the time it takes to execute the event due to re-climbing or fixing the system, I set out to design a system that did not use mechanical components. The goal is higher reliability, ease of installation, and also safety for the climber because sometimes mechanical switches have injured speed climbers hands.
Below is a video of a sensor concept I’m working on which will apply to the hand sensors at the top of the lane and the foot sensor at the bottom that’s used to detect a false start. These use an IR technology that’s relatively cheap (about $10 per sensor, 2 sensors per “pad.&rdquo
and immune to most IR emitted in ambient lighting situations. Read More...
A problem that has plagued the event is the speed timing systems used are very unreliable. Most of these systems rely on some type of mechanical switch for the foot pedal and the top hand sensor to stop the clock at the finish, the top of the climber’s “lane”. Because the systems malfunction so frequently and can ruin the flow of the event and drastically extend the time it takes to execute the event due to re-climbing or fixing the system, I set out to design a system that did not use mechanical components. The goal is higher reliability, ease of installation, and also safety for the climber because sometimes mechanical switches have injured speed climbers hands.
Below is a video of a sensor concept I’m working on which will apply to the hand sensors at the top of the lane and the foot sensor at the bottom that’s used to detect a false start. These use an IR technology that’s relatively cheap (about $10 per sensor, 2 sensors per “pad.&rdquo
and immune to most IR emitted in ambient lighting situations. Read More...Build an IDC cable from an IDC PCB socket
02/17/2009 13:35 Filed in: Cables
I recently needed to create a cable that had an IDC socket but only had PCB mounted IDC sockets available to work with. It would have been very tedious to try to directly solder wire to the short pins of the PCB IDC socket. It’s easy to find IDC ribbon cables with the plug end, but not the socket end.
What to do? Hack a cable using a 2x5 molex type connector, attached that to the PCB socket and super-glued the two together. The result was effective and what I needed.
This is also a good way to build your own JTAG squid cable if you need one or lost yours that came with the STK500. The cable below is not for JTAG, but a custom cable I made for a SPI interface.
I used the Hansen Hobbies molex connector kit to build the 2x5 molex cable termination. Their crimp and cable making kit is awesome - their site has lots of videos to show you how to build cables. The 2x5 works great to plug it directly into the PCB side of the socke, but the PCB pins are not very long, so it won’t stay by itself. Superglue the bodies together or if you really want it to be sturdy, you could epoxy the two bodies together. Slightly rough up the plastic to help the bond.
Here’s how it looks when it’s done:
What to do? Hack a cable using a 2x5 molex type connector, attached that to the PCB socket and super-glued the two together. The result was effective and what I needed.
This is also a good way to build your own JTAG squid cable if you need one or lost yours that came with the STK500. The cable below is not for JTAG, but a custom cable I made for a SPI interface.
I used the Hansen Hobbies molex connector kit to build the 2x5 molex cable termination. Their crimp and cable making kit is awesome - their site has lots of videos to show you how to build cables. The 2x5 works great to plug it directly into the PCB side of the socke, but the PCB pins are not very long, so it won’t stay by itself. Superglue the bodies together or if you really want it to be sturdy, you could epoxy the two bodies together. Slightly rough up the plastic to help the bond.
Here’s how it looks when it’s done:
asdfasdf
