From: Sean L. <se...@cs...> - 2005-03-02 18:53:27
|
If I'm understanding correctly from the discussion, it sounds like there are three pins for each digital in/out and analog in: power, ground, and signal return. And that the power is presently tied to the raw unregulated power coming into the board (V_BATT?). If this is correct (and I could be misunderstanding), it should *definitely* be changed. A very high percentage of robotics applications for which this board will be used will be running off of batteries whose voltage fluctuates with draw. Sensors of various types absolutely need to have regulated power and don't have their own regulators. Make sure they're getting regulated power through the power pin, and for the same reason I'd strongly suggest a bigger regulator: 700ma may not be sufficient for a large load of sophisticated sensors. >= 1A is desirable. As to higher voltage than 6V: we're presently driving the acroname Brainstems we're using off of 6V 5-cell A or Sub-C packs, with servo power and power to the board tied to the same source (you should provide a jumper or solder jump to do this also). This is because servos cannot run off of more than 6V or they risk damage. So having the board run on 6V seems to be a reasonable value. Craig, if you could hold off for a bit I will forward stuff to the hackers in my class and have them post responses and suggestions. Sean |
From: Sean L. <se...@cs...> - 2005-03-03 00:57:19
|
Arthur Magill wrote: > If you're looking for more than an amp, isn't it reasonable to have a > regulator on the board drawing the current? It must already be doing > something substantial. But, it is extremely useful to have a clean > regulated +5V to send to some simple sensor board to power a little > logic. 500mA should be enough for most - that's still quite a whack. > Just because Vcc5 is present on the header, doesn't mean you have to > use it. I can appreciate the opinion, but I think it strongly misjudges what I think will be the primary users of this board: robotics hobbyists and small-robot researchers and educators. For these people (myself included), the sensors are modular: pull one sensor, plug in another the next day from some other microcontroller. Many such sensors need regulated power, and requiring them to be jury-rigged to a regulated power pin elsewhere on the board, or to their own power regulator, hurts modularity quite considerably. The analog and digital pins' Vcc *really* needs to be regulated. [of course, this may be moot if they already are -- in that case, my apologies Craig] While we're at it, I wanted to verify that (as the schematic _appears_ to be saying) the sensor pins are in the order ground-power-signal, just as the servo pins are. If not, please make them so. Sean |
From: Arthur M. <ar...@ar...> - 2005-03-03 09:44:16
|
> I can appreciate the opinion, but I think it strongly misjudges what I > think will be the primary users of this board: robotics hobbyists and > small-robot researchers and educators. For these people (myself > included), the sensors are modular: pull one sensor, plug in another the > next day from some other microcontroller. Many such sensors need > regulated power, and requiring them to be jury-rigged to a regulated > power pin elsewhere on the board, or to their own power regulator, hurts > modularity quite considerably. I haven't really used modular sensors (prefer to roll my own), so I didn't really get the problem. Sounds like you have a good case after all. Maybe this is a case for another jumper? The robostix board provides Vsensor, which can be jumpered to either take Vcc5 to 500mA, or an offboard supply that can be anything you like. It would allow big heatsinking, etc, somewhere offboard, but still provide power straight to sensors. Or, if you're doing something fairly low power, just use the ATMega128 Vcc5 as before. > The analog and digital pins' Vcc *really* needs to be regulated. Absolutely. Gordon, you're a brave man, asking this many people for an opinion ;-) However it works out though, these are just details. The robostix looks like a useful board. Arthur This message has been checked for viruses but the contents of an attachment may still contain software viruses, which could damage your computer system: you are advised to perform your own checks. Email communications with the University of Nottingham may be monitored as permitted by UK legislation. |
From: Craig H. <cr...@hu...> - 2005-03-03 17:51:18
|
On Mar 3, 2005, at 1:46 AM, Arthur Magill wrote: > Gordon, you're a brave man, asking this many people for an opinion ;-) Some companies pay 3rd parties good money to organize focus groups. We just ask people what they think :) C |
From: Gordon K. <go...@gu...> - 2005-03-04 05:43:22
|
We found a supplier of RS-MMC cards (half the physical dimension of regular MMC cards, so they don't stick out the side of the MMC connector on the 'stix) in capacities 256MB and 512M; so, we have dropped the larger-size, smaller-capacity, cards in favour of these. I am in general hesitant to do new product announcements here on the mailing list; however, I know many of you wanted higher capacity MMC cards, for a while the supply of these might be limited, and I wanted you guys to get the first shot at them. Gordon |
From: Jay P. <jay...@gm...> - 2005-03-03 21:13:21
|
I've seen some boards with the servo type arrangement, but at the end is a two position jumper-- you can chose to provide low amperage regulated 5 V on the power pins in the header, or you can choose to provide battery power at whatever voltage it is. ... that way if you need something funny, you can deal with the voltage seperately. Alternatively, if no 5V regulated power is available... a simple header to allow us to plug in a 5 v source to the row of pins in servo configuration would work fine. Its much more valuable to have those three rows of pins so that standard servo plugs will plug in, than to have just the right power applied. I'll supply my own power if necessary. On Thu, 3 Mar 2005 09:51:34 -0800, Craig Hughes <cr...@hu...> wrote: > On Mar 3, 2005, at 1:46 AM, Arthur Magill wrote: > > > Gordon, you're a brave man, asking this many people for an opinion ;-) > > Some companies pay 3rd parties good money to organize focus groups. We > just ask people what they think :) > > C > > ------------------------------------------------------- > SF email is sponsored by - The IT Product Guide > Read honest & candid reviews on hundreds of IT Products from real users. > Discover which products truly live up to the hype. Start reading now. > http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users > |
From: Dave H. <dhy...@gm...> - 2005-03-04 13:10:34
|
Hi Jay, > Its much more valuable to have those three rows of pins so that > standard servo plugs will plug in, than to have just the right power > applied. I'll supply my own power if necessary. I don't think anybody would disagree with you. All of Gordon's proposals have had 3 pin connectors for the servos, and they've all had a place to power the servo seperately from the main supply. -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ |
From: Arthur M. <ar...@ar...> - 2005-03-02 19:05:34
|
> Make sure they're getting > regulated power through the power pin, and for the same reason I'd > strongly suggest a bigger regulator: 700ma may not be sufficient for a > large load of sophisticated sensors. >= 1A is desirable. If you're looking for more than an amp, isn't it reasonable to have a regulator on the board drawing the current? It must already be doing something substantial. But, it is extremely useful to have a clean regulated +5V to send to some simple sensor board to power a little logic. 500mA should be enough for most - that's still quite a whack. Just because Vcc5 is present on the header, doesn't mean you have to use it. Just my tupence worth ;-) Arthur This message has been checked for viruses but the contents of an attachment may still contain software viruses, which could damage your computer system: you are advised to perform your own checks. Email communications with the University of Nottingham may be monitored as permitted by UK legislation. |