Microcontroller Recommendations for School Project: Laser Tag

I'm taking a senior design class in college (I'm an Electrical/
Computer Engineering major) and my final project is a laser tag game.
My partner and I are trying to pick a good microcontroller for the
guns and we're looking for recommendations. Throughout the class we've
been working with the Freescale/Motorola 6811 (very old school) and
writing pure assembly code but we can pick any modern microcontroller
for the project. The guns need to communicate wirelessly with a base
station so our professor recommended a chip that has ZigBee support
but it's not a requirement - something with a relatively user-friendly
RF protocol is probably important though. Also we'd like to use some
sort of IR protocol (for the "laser" shots) but we haven't found many
chips that come with this built-in and so we are thinking about using
an external module chip that does IR encoding/decoding (a
recommendation on one of these to use with the microcontroller would
be awesome). For the optics part of the project we're basically
following this (http://www.lasertagparts.com/mtoptics.htm) and using
the IR emitters/receivers that they use. If you could recommend any
microcontrollers/components for this project I would appreciate it
very much! Thanks.

D-Shap wrote:
> I'm taking a senior design class in college (I'm an Electrical/
> Computer Engineering major) and my final project is a laser tag game.
> My partner and I are trying to pick a good microcontroller for the
> guns and we're looking for recommendations. Throughout the class we've
> been working with the Freescale/Motorola 6811 (very old school) and
> writing pure assembly code but we can pick any modern microcontroller
> for the project. The guns need to communicate wirelessly with a base
> station so our professor recommended a chip that has ZigBee support
> but it's not a requirement - something with a relatively user-friendly
> RF protocol is probably important though. Also we'd like to use some
> sort of IR protocol (for the "laser" shots) but we haven't found many
> chips that come with this built-in and so we are thinking about using
> an external module chip that does IR encoding/decoding (a
> recommendation on one of these to use with the microcontroller would
> be awesome). For the optics part of the project we're basically
> following this (http://www.lasertagparts.com/mtoptics.htm) and using
> the IR emitters/receivers that they use. If you could recommend any
> microcontrollers/components for this project I would appreciate it
> very much! Thanks.
>

Look at TI MSP430. Lot's of low power stuff and I think they have one with
ZigBee support.

--
Scott
Validated Software
Lafayette, CO



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On Thu, 22 Oct 2009 08:09:06 -0700 (PDT), D-Shap <>
wrote:

>I'm taking a senior design class in college (I'm an Electrical/
>Computer Engineering major) and my final project is a laser tag game.
>My partner and I are trying to pick a good microcontroller for the
>guns and we're looking for recommendations. Throughout the class we've
>been working with the Freescale/Motorola 6811 (very old school) and
>writing pure assembly code but we can pick any modern microcontroller
>for the project.

A good rule of thumb is that in considering what processor to use,
familiarity gets a lot of extra weight. You probably already have code
snippets that take care of the basic initialization, housekeeping, I/O,
and so forth; build on that.

OTOH, it's always good to take an opportunity to learn another piece of
silicon. The AVR chips from Atmel have a lot of exposure in the
enthusiast/hobby arena since many are available in DIP form factors and
run on 5 VDC and their logical layout is comfortable (a nice set of
registers, useful peripherals).

> The guns need to communicate wirelessly with a base
>station so our professor recommended a chip that has ZigBee support
>but it's not a requirement - something with a relatively user-friendly
>RF protocol is probably important though.

The guns or the targets (receivers) need to talk to the base station?

The RF can be an external block, lower down in the protocol stack. Hop
over to Sparkfun <http://www.sparkfun.com/commerce/categories.php> and
look around their Wireless section for some ideas.

> Also we'd like to use some
>sort of IR protocol (for the "laser" shots) but we haven't found many
>chips that come with this built-in and so we are thinking about using
>an external module chip that does IR encoding/decoding (a
>recommendation on one of these to use with the microcontroller would
>be awesome).

Would you need anything more than a bitstream from each "gun" that is a
unique identifier? Try something on the order of: sync, header, ID
number, checksum. Use the widely available 38 kHz modulation scheme
(lots of receivers available).

--
Rich Webb Norfolk, VA

On Oct 22, 11:36*am, "Not Really Me"
<sc...@validatedQWERTYsoftware.XYZZY.com> wrote:

> > microcontrollers/components for this project I would appreciate it
> > very much! Thanks.
>
> Look at TI MSP430. *Lot's of low power stuff and I think they have one with
> ZigBee support.

But he doesn't really want to design a Zigbee module. This question
started on aardvark, where my response was:

Well, for a variety of reasons I would suggest you use the Microchip
Zigbee module MRF24J40, because it's cheap ($10) and has the antenna
and everything integrated: http://www.microchip.com/wwwproducts...cName=en027752

Using this device will be easiest if you use a Microchip MCU because
they provide all the control software.

All the compilers you will need are free. Microchip will also send you
samples of the microcontroller free (you'll have to pay for the Zigbee
modules though). You will however have to invest in a programming
adapter, which one you choose depends on which specific micro you end
up using. The PICkit 2 programmer covers quite a lot of ground at a
reasonable price. There are third-party clones on eBay also.

As far as the IR goes, the usual way of doing it is to modulate the IR
LED at a fairly high rate (30kHz or more) and gate the modulation to
create a pulse train identifying the transmitter. A PWM output from
the micro can drive the LED, and on the other end you'll use a canned
IR receiver solution as used in TV remote control applications - it
has a phototransistor and a filter to reject non-modulated light
inputs. You need to pick the receiver to match your modulation
frequency. What you get out of the receiver is your raw data pulse
train (with the 30kHz or whatever carrier subtracted out).

An example:

http://www.radioshack.com/product/in...ductId=2049727

In article <7da10c21-82a5-4377-acf6-
>, says...
> I'm taking a senior design class in college (I'm an Electrical/
> Computer Engineering major) and my final project is a laser tag game.
> My partner and I are trying to pick a good microcontroller for the
> guns and we're looking for recommendations. Throughout the class we've
> been working with the Freescale/Motorola 6811 (very old school) and
> writing pure assembly code but we can pick any modern microcontroller
> for the project. The guns need to communicate wirelessly with a base
> station so our professor recommended a chip that has ZigBee support
> but it's not a requirement - something with a relatively user-friendly
> RF protocol is probably important though.
......

Why do you need wireless?

People go round 'shooting each other', unit detects if it has been hit
and by which code. At end of game download the table of "been hit by"
even via serial links as the equipment is returned (and reset for next
game) collate the table of codes of who was hit by who into transposed
matrix of "who hit who" print results.

Nobody needs the results until the end anyway.

Don't make it too complicated otherwise you will never complete the
project. You will have enough to do with creating the detector arrays
to put on the player and link to the gun, as well as multiple
simultaneous hits (e.g. three people hit same person at same time). If
you want to save power and make things easier save results in gun/back
pack, forget wireless.

Let alone someones bluetooth phone/pda/gadget interferring with zigbee
just when you need it NOT to. Let alone the fact that wifi is in the
same band and many devices have wifi built in as well (e.g. iPhone).

--
Paul Carpenter |
<http://www.pcserviceselectronics.co.uk/> PC Services
<http://www.pcserviceselectronics.co.uk/fonts/> Timing Diagram Font
<http://www.gnuh8.org.uk/> GNU H8 - compiler & Renesas H8/H8S/H8 Tiny
<http://www.badweb.org.uk/> For those web sites you hate

On Oct 23, 7:05*am, Paul Carpenter wrote....
>
> Why do you need wireless?
>
> People go round 'shooting each other', unit detects if it has been hit
> and by which code. At end of game download the table of "been hit by"
> even via serial links as the equipment is returned (and reset for next
> game) collate the table of codes of who was hit by who into transposed
> matrix of "who hit who" print results.
>
> Nobody needs the results until the end anyway.
>
> Don't make it too complicated otherwise you will never complete the
> project.

Sound advice.
One detail that I'd make use of, is you will already have a working
IR data transmitter, and working IR receivers - and data stream
encoders and decoders
so make a PC Score Reader module that uses the Gun IR to send the
scores, and that avoids serial cable clutter, but still keeps things
simple - and it reuses the proven code blocks.

RF links can always be added later....

I'd also look into SiLabs Toolsticks - when I had a dialog with them
back in March, they were improving what they call "Toolstick
Terminal", that allows data coms to a PC file, via the debug channel.
- so you may be able to use the Debug connector on a receiver, as the
PC link pathway to a file (which you then post-process)
They expected ~June for this IDE change.

Hi,
Is the Microchip Zigbee module MRF24J40 useable with an Atmel mcu?.

And, when you say "Using this device will be easiest if you use a Microchip
MCU because they provide all the control software.", does this mean the
software is not compatible with other mcus (like Atmel)?.




"larwe" <> wrote in message
news:79cc3b5f-a780-4d02-aa87-...
On Oct 22, 11:36 am, "Not Really Me"
<sc...@validatedQWERTYsoftware.XYZZY.com> wrote:

> > microcontrollers/components for this project I would appreciate it
> > very much! Thanks.
>
> Look at TI MSP430. Lot's of low power stuff and I think they have one with
> ZigBee support.

But he doesn't really want to design a Zigbee module. This question
started on aardvark, where my response was:

Well, for a variety of reasons I would suggest you use the Microchip
Zigbee module MRF24J40, because it's cheap ($10) and has the antenna
and everything integrated:
http://www.microchip.com/wwwproducts...cName=en027752

Using this device will be easiest if you use a Microchip MCU because
they provide all the control software.

All the compilers you will need are free. Microchip will also send you
samples of the microcontroller free (you'll have to pay for the Zigbee
modules though). You will however have to invest in a programming
adapter, which one you choose depends on which specific micro you end
up using. The PICkit 2 programmer covers quite a lot of ground at a
reasonable price. There are third-party clones on eBay also.

As far as the IR goes, the usual way of doing it is to modulate the IR
LED at a fairly high rate (30kHz or more) and gate the modulation to
create a pulse train identifying the transmitter. A PWM output from
the micro can drive the LED, and on the other end you'll use a canned
IR receiver solution as used in TV remote control applications - it
has a phototransistor and a filter to reject non-modulated light
inputs. You need to pick the receiver to match your modulation
frequency. What you get out of the receiver is your raw data pulse
train (with the 30kHz or whatever carrier subtracted out).

An example:

http://www.radioshack.com/product/in...ductId=2049727

"D-Shap" <> wrote in message
news:7da10c21-82a5-4377-acf6-...
> I'm taking a senior design class in college (I'm an Electrical/
> Computer Engineering major) and my final project is a laser tag game.
> My partner and I are trying to pick a good microcontroller for the
> guns and we're looking for recommendations. Throughout the class we've
> been working with the Freescale/Motorola 6811 (very old school) and
> writing pure assembly code but we can pick any modern microcontroller
> for the project. The guns need to communicate wirelessly with a base
> station so our professor recommended a chip that has ZigBee support
> but it's not a requirement - something with a relatively user-friendly
> RF protocol is probably important though. Also we'd like to use some
> sort of IR protocol (for the "laser" shots) but we haven't found many
> chips that come with this built-in and so we are thinking about using
> an external module chip that does IR encoding/decoding (a
> recommendation on one of these to use with the microcontroller would
> be awesome). For the optics part of the project we're basically
> following this (http://www.lasertagparts.com/mtoptics.htm) and using
> the IR emitters/receivers that they use. If you could recommend any
> microcontrollers/components for this project I would appreciate it
> very much! Thanks.

I'm the 'GrandDaddy of Laser Tag.... if you have done your research, you
will know who I am, having designed laser tag systems since 1989. I'd be
happy to help/advise off group.
I would not use a zigbee device for a start...The processor of (my) choice
would be an atmel part with 64K flash.
I/R encoding/decoding can be done by the processor, including the 38/40K
modulation.Either AVR or 51 core. I'm sure there's a myriad of other
suitable vendors( dallas 89c450).
Design the whole core around interrupts and 'goto to sleep mode' while doing
nothing to get long battery life.
2.4G for radio is not the right choice- range and obstacle interference are
a real issue so look at 868/433 or whatever is correct for your FCC regs.
Chose I/R detectors with a metal can.The cheap plastic ones are poor on
interference rejection. U/V strip lighting in a laser arena are a nightmare
for generating interference.

>
> Why do you need wireless?
>
> People go round 'shooting each other', unit detects if it has been hit
> and by which code. At end of game download the table of "been hit by"
> even via serial links as the equipment is returned (and reset for next
> game) collate the table of codes of who was hit by who into transposed
> matrix of "who hit who" print results.
>
> Nobody needs the results until the end anyway.

Real time 'position/status ranking', that's why.

>
> Don't make it too complicated otherwise you will never complete the
> project. You will have enough to do with creating the detector arrays
> to put on the player and link to the gun, as well as multiple
> simultaneous hits (e.g. three people hit same person at same time). If
> you want to save power and make things easier save results in gun/back
> pack, forget wireless.

I agree with the bit about never completing the project
Multiple simultaneous hits? Impossible.
If there are two concurrent incoming I/R streams ( statistically unlikely,
but possible), the Rx data from the IR detector will be garbage, and
rejected by the processing mechanism.

>
> Let alone someones bluetooth phone/pda/gadget interferring with zigbee
> just when you need it NOT to. Let alone the fact that wifi is in the
> same band and many devices have wifi built in as well (e.g. iPhone).

With the right frequency choice, there wil be no issues here with SRD.
>
> --
> Paul Carpenter |
> <http://www.pcserviceselectronics.co.uk/> PC Services
> <http://www.pcserviceselectronics.co.uk/fonts/> Timing Diagram Font
> <http://www.gnuh8.org.uk/> GNU H8 - compiler & Renesas H8/H8S/H8 Tiny
> <http://www.badweb.org.uk/> For those web sites you hate

In article <hfdEm.35405$2>,
says...
> >
> > Why do you need wireless?
> >
> > People go round 'shooting each other', unit detects if it has been hit
> > and by which code. At end of game download the table of "been hit by"
> > even via serial links as the equipment is returned (and reset for next
> > game) collate the table of codes of who was hit by who into transposed
> > matrix of "who hit who" print results.
> >
> > Nobody needs the results until the end anyway.
>
> Real time 'position/status ranking', that's why.

To be seen by who?

You are assuming that the majority of people taking part in these games
are VERY large crowds, where they monitor the current teams. This is
rare as the majority of these games every day are used by small teams
sometimes I have seen places where different groups get involved, to get
the numbers up.

> > Don't make it too complicated otherwise you will never complete the
> > project. You will have enough to do with creating the detector arrays
> > to put on the player and link to the gun, as well as multiple
> > simultaneous hits (e.g. three people hit same person at same time). If
> > you want to save power and make things easier save results in gun/back
> > pack, forget wireless.
>
> I agree with the bit about never completing the project
> Multiple simultaneous hits? Impossible.

Have you ever seen one of these 'laser' game shoot em ups?

Competitors have sensors usually donned like a bullet proof vest,
that has multiple sensors, to detect 'hits' on back, front, and sides,
sometimes also detect gun, legs, arms.

So multiple hits from different sensors is VERY LIKELY.

> If there are two concurrent incoming I/R streams ( statistically unlikely,
> but possible), the Rx data from the IR detector will be garbage, and
> rejected by the processing mechanism.

Two into same sensor, but the system each competitor 'wears' has to deal
with MULTIPLE sensors.

> > Let alone someones bluetooth phone/pda/gadget interferring with zigbee
> > just when you need it NOT to. Let alone the fact that wifi is in the
> > same band and many devices have wifi built in as well (e.g. iPhone).
>
> With the right frequency choice, there wil be no issues here with SRD.

The frequency choice being avoid 2.4 GHz like the plague, with
potentially so many nodes, the collision, dead spots, range and
interference problems are horrendous.

What's inside the 'arena' and what the walls of the arena are made of
will effect range and transmission paths. Having seen too many cases
where 2.4GHz devices have trouble going from one room to the next.

--
Paul Carpenter |
<http://www.pcserviceselectronics.co.uk/> PC Services
<http://www.pcserviceselectronics.co.uk/fonts/> Timing Diagram Font
<http://www.gnuh8.org.uk/> GNU H8 - compiler & Renesas H8/H8S/H8 Tiny
<http://www.badweb.org.uk/> For those web sites you hate