Archery Timing System - thoughts?

No hardware specified yet and no code written. This is just a sanity check and request for input to clarify my thinking (and perhaps point out things I have forgotten).

This is my second Arduino project, so I am not a total novice. My first was a display box for a 5-axis motor-controlled stage on a big scientific instrument. (UNO with Ethernet shield. Fairly simple messaging through UDP for updating any axis display and some commands for configuring the box, stored in EEPROM. Each axis display made from 2 4-digit 7-segment display driven with SPI).

I am looking to put together a flexible archery timing system. There are others out there but they are very expensive. I do not begrudge people making money on these as they are fairly niche and the companies have development costs to cover. However for small clubs we can not afford this and I would like to give this a go for my own interest too.

I have a number of design major decisions to make, and this is where I would like some feedback. Penny pinching is not needed, though I don’t want to be spending mega-bucks.The basic system will likely be as follows.

A central control unit (required)
Used by the judges to start and stop timing. Timing sequences can vary depending on the tournament. The actual programming of this will be somewhat complicated, but I think I can handle this (programming is my day job). Typically there will also need to be a number of buttons (up to about 10) for various start/stop/abort functions and possibly some menu functionality to pick timing sequences (hence some form of display like a 20x4 LCD). I will also use the display to show the count down on this box for the director of shooting. While at some venues mains power may be available that can not be guaranteed, so the system must have a battery option and ideally be able to run for at least 12 hours and preferably 2 days of 12-hours a day. (I will come on to communication in a moment).

Various Display/sound units
Similar commercial systems are supplied with a 2 or 3 different displays which need to be visible from about 60-80m. These display
a. count-down in seconds and a set of traffic lights (this may be optional but would be nice),
b. which groups should be shooting (alternates) (could be on the first display as instead)
c. a set of loudspeakers for audible start/stop. Could be part of the main display but for flexibility a seperate box would be good.

The main commercial system runs off 24v (2 car batteries strapped together) which can power for 2 days. It is cabled with some form of serial connection which also carries power (24v I believe) for all the display boards and speakers. This means a number of daisy-chained 30m cables which the archers regularly trip over thus disabling the timing displays!!

I am wondering about going to Wireless communications (Ciseco radios I think as they should happily do 300m with line of sight and they look quite nice in the way they work. http://shop.ciseco.co.uk/rf-module-range/). Then perhaps locating smaller batteries with each unit.

I guess my questions are these.

  1. Anyone have experience with the Ciseco radio devices (positive or negative)?

  2. Can anyone give me good reasons to stick with a wired approach (including power distribution)?

  3. I am likely to put some form of arduino (or similar) in the remote units. I would like to ensure that several time display boards stay in step. Would I be better just starting the time with a single radio command and assuming the clocking is accurate enough for display to stay in synch (I am only looking for a maximum of 240 seconds). Alternatively would I be better sending out a change each second from the controller. The Ciseco devices could be set to all listen on the same command broadcast? I will probably play with sketching each approach, but thought there might be some exiting experience of this sort of issue. My feeling is that over 240 seconds I shouldn’t see any drift between displays.

  4. I have spent a lot of time trying to locate supplies to make large LCD displays. I am looking for the equivalent of 7-segment digits at least about 4 inches tall, maybe bigger. Something like this (these are 4 inches tall).

My googling skills have let me down. I can find any number of small 16x2, 8x2, 20x4 etc LCD modules, and up to 6 inch single digit 7-segment LEDs. However these would probably take more power than I would want to run off a battery (unless some else can tell me differently).

Thanks

LCD Display.png

I spend a good deal of time dealing with networked additions over multi drop serial busses. My main reason for preferring wired is pretty simple: you can carry power, you usually save money, and you don't have to worry about interference(either getting it or making it) nearly as much.

You have a special circumstance because archers are tripping on cables. Usually tripping on cables is a sign of cables not being run properly. Can you change your cable layout to avoid tripping? Or cover your cables in Orange tape? Stake them to the ground? Cover them?

Using a serial protocol that doesn't require all nodes to be in one long run and allows branching helps. Usually this is done with CAN or RS485 by turning the data rate way down so that reflections are a non issue. This doesn't sound like a high bandwidth application to me.

I'm imagining it will be fairly bright out, so you will probably want some big LED displays, either 7 segment or actual dot matrix displays. You might have to order on eBay from China to get a good deal.

As for power, your biggest consumers will be the displays, the audio, and depending on the modules you use, the wireless communication, but power shouldn't be a major issue since you aren't powering a jet aircraft or anything.

I don't have any experience with those RF modules but someone probably does. If you use them, though, you'll need to get power to you boxes somehow. Will each have it's own battery?

Oh, and if you do run power from a 24V battery through long cables, please use a fuse so you don't start a fire! Will this ever be used in wet conditions?

Wet conditions....?

Oh, Yes!

Particularly in England.

I live in Seattle, and I imagine our weather is somewhat similar to yours...

Waterproofing things could be a challenge. I like Tupperware, but that takes a lot of effort to make it look decent(but the displays facing out the bottom, and cover the whole thing with plastic panels to hide the fact that it is in fact tupperware), or it winds up looking kinda hacked together.

Cable glands are your friend, and all your cables should be outdoor or better yet direct burial rated, if you do actually go with the wired approach.

Did you try archeryclock .com http://www.archeryclock.com/LedScreen.html http://www.archeryclock.com/Schematics.html Using arduino mega. And ledstrips. And wireless (rf serial) connection.

I have a board with TPIC6B595 shift registers for driving 7 segment displays made from LED strips, each with a '328P. Mate up with an RF receiver, have it display whatever the master time keeping system tells it to. Can run 6-LED segment displays (make from LED strips) and 11V LiPo battery for hours, only depends on how big a battery you use. 8 Hrs would not be hard. http://www.crossroadsfencing.com/BobuinoRev17/

Thanks hjegers and Crossroads.

I had seen the Archery Clock stuff after I started this thread. Unfortunately at the moment all my arduino play-time is on hold. Paid work is getting in the way.

FlyingWhale: 1. Anyone have experience with the Ciseco radio devices (positive or negative)?

Can't help you there.

FlyingWhale: 2. Can anyone give me good reasons to stick with a wired approach (including power distribution)?

Three reasons actually. 1} Reliability. 2} Timing. 3} Batteries.

I was prone to say "Reliability, Reliability, Reliability" but I bit my tongue (as it were).

As has been pointed out, if people trip over cables, you haven't laid the cables properly. Radio is prone to interference and the modules available (albeit haven't looked at the Ciseco system) are on "ISM" bands shared with myriad other devices all wanting to monopolise the spectrum at any given (random) time. Any form of reliable control is based on "packet" protocols with return acknowledgements, which process may be delayed until an interfering source desists. And it should be blatantly obvious that every device connected by radio must have a battery which you must check, charge or replace on every deployment.

FlyingWhale: 3. I would like to ensure that several time display boards stay in step. Would I be better just starting the time with a single radio command and assuming the clocking is accurate enough for display to stay in synch (I am only looking for a maximum of 240 seconds). Alternatively would I be better sending out a change each second from the controller.

The Arduino (using a crystal clock) will not drift to any concerning degree. The problem is as mentioned, that you will have to use a protocol that verifies that the command to set the time was correctly received by each unit, by comparing the time that unit returns with that sent.

FlyingWhale: 4. I have spent a lot of time trying to locate supplies to make large LCD displays. I am looking for the equivalent of 7-segment digits at least about 4 inches tall, maybe bigger. Something like this (these are 4 inches tall).

So where did you find those? Looking at it another way, where in your normal activities have you seen LCD displays of that sort actually in use?

Thanks for the input. All responses are welcome. Even pointing out what may be blatantly obvious. Sometimes it is necessary, and not all of us spot the blatantly obvious... 8)

Paul__B:

FlyingWhale: 4. I have spent a lot of time trying to locate supplies to make large LCD displays. I am looking for the equivalent of 7-segment digits at least about 4 inches tall, maybe bigger. Something like this (these are 4 inches tall).

So where did you find those? Looking at it another way, where in your normal activities have you seen LCD displays of that sort actually in use?

The only ones I have seen like this are on an existing archery timer setup (e.g. http://www.pats-archery.com/DANAGE-Timing-Display-with-Traffic-Lights-Large-1). Unfortunately a full setup runs to about $8k-$10k. Each board is around $2k-$3k. It is admittedly a low volume market and the company is commercial so have to make money. It just puts it out of the reach of most except national organizations.

Can you use something like this vs LCD? http://www.kiefer.com/kiefer-31--digital-pace-clock---rechargeable-products-1775.php?page_id=160 These are 6 LED/segment, about 9 inch tall digits.