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Topic: Access to T1,T3 and T4 inputs on Mega 1280, etc. (Read 2 times) previous topic - next topic

Paul Stoffregen


But that doesn't mean that you'll get official agreement that T1/T3/T4 should have been accessible...


Maybe not, but I would absolutely agree with wholder's original post.  It's a shame those pins weren't at least brought to pads within the large interior space of the Mega, and assigned higher pin numbers, so they could at least be used.

It is a strength of Arduino that hardware can be utilized.  But in this case, with 4 on-chip 16 bit timers, only 2 of them have ICP pins exposed and only one has the clock input pin exposed.  You can't actually use those other timers for these hardware functions, much like a Basic Stamp, due to design decisions made in the board layout and pin assignments.

I believe that's really unfortunate.

wholder

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But that doesn't mean that you'll get official agreement that T1/T3/T4 should have been accessible...

I hate to sound harsh, but don't the makers of "closed" hardware make just those source of arguments about what kinds of uses are "permissible" with their hardware?  I would certainly hope that Arduino not become closed to certain uses and applications just because someone feels that Arduino is only really intended for a certain target audience build "permissible" sorts of projects...

Come, on is it really that hard to at least makes these extra functions available in some form that doesn't require micro soldering skills just to make an electrical connection?  Are these digital pins so extraordinarily dangerous that we must make sure novice users cannot get access to them?

Wayne

retrolefty



But that doesn't mean that you'll get official agreement that T1/T3/T4 should have been accessible...


Maybe not, but I would absolutely agree with wholder's original post.  It's a shame those pins weren't at least brought to pads within the large interior space of the Mega, and assigned higher pin numbers, so they could at least be used.

It is a strength of Arduino that hardware can be utilized.  But in this case, with 4 on-chip 16 bit timers, only 2 of them have ICP pins exposed and only one has the clock input pin exposed.  You can't actually use those other timers for these hardware functions, much like a Basic Stamp, due to design decisions made in the board layout and pin assignments.

I believe that's really unfortunate.



Well it was noted by the forum community when the first mega1280 board was released that there were 16 I/O pins not exposed to PCB traces or pads. But being a open source project, another vendor, Seeeduino, built their version of the mega1280 board that went ahead and brought those pins to a added header connector. So for those that want to utilize such pins there is a path to proceed without having to build your own board, but you will have to supply your own software functions in some cases to support using those added pins.

To suggest that the arduino team must meet all requirements to all users in all their products is somewhat unrealistic, there are always trade-offs to be made for any engineering effort. At least the open source nature of the arduino platform allows SOMEONE to proceed if they so wish as there are no proprietary, trade secrets, or closed source code to prevent improvements.

I have several issues with most of the arduino boards such as the auto voltage selection design, auto-reset design, shield connector spacing, and that is just on the hardware side. But none of these things are show stoppers that can't be worked around or eliminated by selecting another vendor's version of a compatible design. The easy part is finding faults with others decisions, but that need not stop progress for users. It's not like you need permission to change anything you have the ability to change.
   
Lefty

westfw

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But that doesn't mean that you'll get official agreement that T1/T3/T4 should have been accessible...

I hate to sound harsh, but don't the makers of "closed" hardware make just those source of arguments about what kinds of uses are "permissible" with their hardware?

I think you're reading too much into my words.  You probably also won't get a strong statement of "yes, we left those unconnected intentionally because we don't want people using the timers for other than their official purpose!"  It'd probably be more along the lines of "oh.  We didn't think anyone was using that feature, so we focused on getting more PWMs and analog inputs out..."  (I think this is the first thread I've seen complaining about these particular pins being missing, for example.)

And the big difference in this case is that you can download the schematics and pcb design, add the extra pads (or replace other pads) yourself.  I don't think it will be as easy as you think; given the design rules that they're using, it's pretty hard to find space for anything as big as am extra pad.  The MEGA board doesn't have a bunch of empty area; it's got areas that are covered with TRACES.

OTOH, it's clearly possible, since Seeed has done it...

wholder


I don't think it will be as easy as you think; given the design rules that they're using, it's pretty hard to find space for anything as big as am extra pad.  The MEGA board doesn't have a bunch of empty area; it's got areas that are covered with TRACES.

OTOH, it's clearly possible, since Seeed has done it...

Actually, as your own OTOH points out, there's plenty of room on the Mega 1280 board for lots of new pads and traces.  This is especially true considering that the Seeed board brings all the traces to pads on a PCB that's significantly *smaller*.

But, I don't want to get into an argument here.  I would simply like to put forward the proposal (humble request) that, henceforth, pins not be sacrificed in this fashion on new Ardiuno designs.  I don't know who decides these things, but it would be really great if they could consider trying to go the extra mile and leave no pins behind!

Wayne

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