Parts and APPMods

Gadgetman

I'm curious as to what kind of parts Parallax will be stocking as most of the parts already in the shop is for 5V.

The MAX7219 LED-driver doesn't work at 3.3V, and·Maxim reccommends the MAX6951 instead.
(·All right, I just ordered an even 1K of Surface-mount yellow/green LEDs... They were on sale and cost me about $12, so why not... )

Then there's those RAMTRON FRAM chips.

Voltage regulators?

3.3V/5V logic buffers?

Yes, these are all available from other sources, but when I order I prefer to order it from one place to save on shipping.


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Tom Walker

...not to mention, if Parallax is stocking it, you can be sure that there will be good doc on how to interface it...

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Truly Understand the Fundamentals and the Path will be so much easier...

Paul Baker

I see a possible problem with them doing so, thier core business is the Stamp. They really market the thing as an introductory platform into the world of microcontrollers. As such many people buying the stamp and various accessories have little to no experience with electronics. If you notice, every single last accessory they sell is compatible with the stamp, there are no SX only accsessories (SX development products don't count, Im talking about sensors, sound modules etc).

With that said, the propeller will not be marketed as a introductory platform, it will marketed towards moderately to extremely experienced users. Now if they start selling products that will only work with the propeller, they will undoubtedly have novices purchasing them and hooking them up to the stamp because they simply don't know better. This could cause wide spread confusion for the beginners, something they have taken great pains to avoid. I know that they could put "Not compatible with Stamps", or put them in a special area of the website. But if you see how many people ask questions that are specifically answered in the beginning of "What's a microcontroller" (ie they couldn't be bothered reading it or it just went over thier head), they will still find a way to get thier hands on propeller only acessories·and try·hooking it up to the stamp·nonetheless, regardless of what steps are taken to try and prevent it.

Another point to consider is that many of the parts that would be sought by propeller users would mean Parallax would have to become a distributor for the manufacturer. Forgeting about the hassle about becoming one (which is quite considerable), Parallax would in almost all cases be a low volume distributor, meaning they wouldn't be able to aquire the parts at a substantial discount to make the effort of carrying them worthwhile.

Finally, I have personally seen thier stock room, and it is filled, every square inch of shelf space is occupied by bins for thier products. So there is a logistical side to stocking additional parts.

Just my $0.02

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·1+1=10

Post Edited (Paul Baker) : 3/16/2006 4:22:35 PM GMT

Jon Williams

As it turns out, many of the modules we've built recently (like the Hitachi 3-Axis accelerometer) actually run at 3.3 volts internally and we have to include a regulator for use in 5v circuits.

Yes, there are a lot design questions/choices in front of us, but these are problems we don't mind solving.

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Jon Williams
Applications Engineer, Parallax

Paul Baker

Excellent point Jon, perhaps such products could be slightly modified to enable propeller users to bypass the onboard regulator, keeping a single product that is configured work with stamps, but could also be used with propellers.


Another point to make, the demo board for the propeller has 2 regulators on it, a 3.3V and a 5V. This is because the PS/2 peripherals (mouse and keyboard) require 5V. The current incarnation of the demo board doesn't have a header for access to the 5V regulator (requiring soldering a wire to the 5V regulator's output), but there are plans to make it availible in the final version.

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·1+1=10

Post Edited (Paul Baker) : 3/16/2006 4:31:21 PM GMT

LoopyByteloose

Many of the EEPROMs out there run from 3.0 or lower - 5.5 volts. Also a lot of the I2C and SPI interface devices don't care.

For the PROPeller,
A two-tier power supply and some thoughtful mix and match is a real alternative because most of us already have a lot of 5.0v components.

It really doesn't have to be a nightmare.
After all, it seems that you cannot keep the world of microprocessors in a 5.0 volt standard.
If and when it becomes harder to get something in 5.0 volt, they can easily make a 3.3 volt BasicStamp too.

Consider it another level of expertise along the way. Evolution or extinction - your choice.
As Jon points out, many of the newer devices are going there.

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"When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan

Chris Savage

Paul Baker said...(trimmed)
Excellent point Jon, perhaps such products could be slightly modified to enable propeller users to bypass the onboard regulator, keeping a single product that is configured work with stamps, but could also be used with propellers.
Another point to make, the demo board for the propeller has 2 regulators on it, a 3.3V and a 5V. This is because the PS/2 peripherals (mouse and keyboard) require 5V.

Paul,

·· You can actually interface 3.3V and 5V devices without more than a resistor in many cases.· As you pointed out the Propeller is already interfacing with the PS/2 devices which are 5V.· I connected the Parallax Serial LCD using a 1K resistor to an I/O line and, using the Serial Object was sending text/commands to it.· As you might imagine I had to jumper the I/O line and ground from the PDB since there is no 5V supply on the current board.· Designs are subject to change and when ready could be different.·

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Chris Savage
Parallax Tech Support
csavage@parallax.com