Subject:
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Re: RCX3 - Can extra hardware functionality be added?
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Newsgroups:
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lugnet.robotics
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Date:
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Sat, 22 Jan 2005 23:52:49 GMT
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Original-From:
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Mr S <szinn_the1@yahoo.com!nomorespam!>
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Viewed:
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1352 times
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I've seen this topic come up several times, and am
curious why no one suggests that the input and output
ports be extended from the RCX to pods. Using the same
form factor constraints limits the possibilities.
Using a more condensed cable connection between the
RCX and the pods allows for more connectors, and the
pods would use the standard 2x2 arrangement.
Additionally, if the output pod also contained the
motor controls (imagine something 1/3 the size of the
RCX) it could not only have the low density 2x2
connectors, it could make additional room in the RCX
for more circuitry. There could be several output pod
options, allowing for the standard 3 ports, all the
way up to 12 ports using multiple pods.
Adding the external power connector is an option that
seems unanimously agreed on, and moving the batteries
to an external pod that uses that connector would also
open up space for more processing power. (read
additional RAM, program storage space etc.) Being able
to locate the batteries in a space more suited to
balance of the creation is a huge advantage.
The h-bridge functions being in the output pod would
allow for many upgrade option kits ( I'm hoping this
sort of thinking makes this option or one like it seem
like something that would improve the bottom line to
the LEGO folks) I can see some of the LEGO inventions
I've seen greatly benefiting from the ability to
extend the output ports (via the pod) to a place more
local to where the motors are being used.
These style of changes would make room for upgrades to
the motor control options, input options, and power
options while remaining steady with plug-n-play
utility and backward compatability.
I can imagine 6 motor outputs on one pod, and possibly
2 pods per RCX3. Imagine an input pre-processor pod
that has odometry functions built-in, and a processor
to linearize the readings from certain sensors so that
the user sees improved intelligibility on sensor
readings and/or increased range?
This type of 'change' makes sense to me. To improve
the capabilities of the current RCX by removing the
physical limitations that the current form factor puts
on the processor inside. This is what transformed the
original home computers like the Atari and C64 into
the huge processing machines that we have in tower
style pc's... we moved the input and outputs away from
the processor to give it more room.
I can even see a flash card slot on the RCX in the
future, and other such enhancements that make it not
only competative with systems like the basic stamp,
but more capable, and still equipped with the most
amazing building system I've ever had the pleasure to
play with :)
I'd personally like to see a LEGO servo motor option
along with suitable LEGO servo motors, and perhaps
built-in DCC functionality in the output pod so we
could connect many motors to one output if they are
not all to be used at once.
Well, that is what I would put down good money for.
Cheers
--- Mark Bellis <mark.bellis@tiscali.co.uk> wrote:
> Having had a good look inside my RCX, I'm thinking
> seriously about what is
> really possible in the same space envelope, whether
> extra ports or functions
> could be added for RCX3.
>
> I think it's useful for us to know what's inside the
> RCX, especially if we want
> to have any input into what's inside the next
> evolution of it, which is one
> reason why I've been looking into the circuits.
> Perhaps our ideas are more
> likely to be taken seriously if we understand the
> constraints of the space
> envelope and available electrical and processing
> power.
>
> Much of the circuit board is quite densely packed
> with components on both sides,
> and the board already has 3 track layers, so the
> only way to fit more ports in
> (with the necessary components) would be to
> hybridise parts of the circuit.
> (Hybridisation is where all the components without
> their cases (just the silicon
> bits) are put together inside one package,
> miniaturising the circuit. The
> resulting hybrid might be a package looking a bit
> like the processor).
>
> I don't think the motor port circuit could be
> miniaturised, as the motor
> controllers are already 90% of the motor port
> circuit and the diodes need to be
> rated for more power, so they should stay as
> discrete components.
>
> The power supply circuit, likewise, needs to be
> rated for power. The capacitors
> are some of the largest components. Does anyone
> know if some of them (6x300uF)
> been removed in the RCX2? Certainly we want the
> original mains input port to be
> put back for RCX3, though this would require the
> same space as the RCX1 power
> circuit.
>
> The sensor ports could be hybridised. Each sensor
> port requires 3 transistors,
> 5 resistors and 1 diode, plus the protection diodes
> and capacitor, which would
> have to stay as discrete components for power
> reasons. If the pull-up
> components were included then all three (or more)
> sensor port circuits could fit
> into one hybrid. However, the sensor port circuits
> surround the port connection
> clips, so the hybrid would have to go elsewhere on
> the board.
>
> The processor, ROM and Octal flip-flops (74HC377)
> could be made into a hybrid.
> This would not save much space, but it might be
> enough for a sensor port hybrid
> to fit on that side of the board. The processor has
> eight ADC ports, of which
> three are used for sensors. Others may be used for
> power supply or motor
> monitoring, but there may be another one free for a
> fourth sensor port.
>
> The display is a finite size and already has its
> controller chip and the sound
> device underneath it, so no space could be saved
> there.
>
> The IR LEDs and receiver device need to be where
> they are, behind a window at
> one end of the unit.
>
> Summarising, there is the possibility that sensor
> ports or the main computer
> parts of the circuit could be shrunk into one IC, as
> long as the components are
> available in die form. Therefore some space could
> be saved on the circuit
> board.
>
> Given that there is a custom IC inside the RC Tower,
> the miniaturisation of
> circuits onto ICs is not impossible. The question
> is more one of the cost
> feasibility for a production run of maybe 300,000
> units.
>
> I think enough circuit board space could be saved
> for a Bluetooth IC to be
> placed in the space. This would give the RCX the
> freedom to wander out of sight
> and still communicate, which would greatly expand
> its roving possibilities,
> including a colony of RCX robots interacting. I'd
> like to see a port for the
> camera to be plugged in, so that this too could take
> advantage of the Bluetooth
> capability, making a remote spy robot!
>
> The port connection clips are within 8mm of the edge
> of the board, so four ports
> of each type across the case width is not possible
> with the current scheme. The
> control center uses leads cut in half with wires to
> the circuit board, but the
> trend is away from this and towards the clips. I
> don't honestly think that any
> more ports could be implemented in the same box,
> unless an alternative connector
> scheme were used.
>
> Those of us with greater robotic ambitions,
> requiring more ports, probably have
> the skills to interface two or more RCXs into one
> robot.
>
> In conclusion, I think TLC did a really great job of
> fitting as much as they
> could into the box. With the addition of Bluetooth
> and the restoration of the
> mains port, the RCX3 would have as much extra
> hardware functionality as
> possible, given the advance in technology since the
> RCX1 was produced.
>
> Perhaps, given the anticipated release date and the
> long programme to produce
> the next RCX, our time to suggest new functions has
> now passed, but at least we
> can understand the limits if not everything we want
> is implemented.
>
> PLMKWYT
>
> Mark
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Message has 2 Replies:
 | | Re: RCX3 - Can extra hardware functionality be added?
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| (...) Having built a number of prototype "clone" bricks, I feel reasonably certain that the RCX's internal space is not the limiting factor. The surface area occupied by 2x2 I/O connectors is the true limit. (Assuming you dedicate a board to hosting (...) (20 years ago, 23-Jan-05, to lugnet.robotics)
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