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2009-04-12 by David VanHorn
Dammit. I got bit again. Now those who know me here, know that this is a hot button issue for me, and I'm posting this to illustrate just how sneaky this problem is. I'm currently using an M644 with 20 Mhz external crystal, for a sensor processing app. I'd scanned the data sheet,
2009-04-11 by Graham Davies
--- In AVR-Chat@yahoogroups.com, "Roy E. Burrage" wrote: > > Here are a couple of application notes > that show the power MOSFET structure ... Well, we've drifted off to power MOSFETs here, so I've changed the subject line. Looking at these applications notes and Fairchild's desc
2009-04-10 by Robert Adsett
Roy E. Burrage wrote: > There's also a "depletion" mode device that's normally on, turned off, > much like a standard JFET device. These were actually called Insulated > Gate Field Effect Transistors (IGFET) back in the old days. I don't > know that these devices are available ex
2009-04-10 by Roy E. Burrage
Here are a couple of application notes that show the power MOSFET structure, how the diode comes about, and that it's there to stay: http://www.vishay.com/docs/70572/70572.pdf http://www.vishay.com/docs/71933/71933.pdf http://www.irf.com/technical-info/appnotes/an-1084.pdf These
2009-04-10 by David VanHorn
> Do you have a reference? I've not heard of a BATFET and the only > reference's I was able to find were TI and Linear datasheets where they > labelled regular mosfets as BAT FET based on its circuit location I > believe. Not offhand, I just remember seeing them on a data sheet s
2009-04-10 by Robert Adsett
Graham Davies wrote: > --- In AVR-Chat@yahoogroups.com, Robert Adsett wrote: >> The diode is inevitable in >> the MOSFET structure isn't it? > > No, I don't think so. Diodes between both source and drain and the substrate are usual, but you can get rid of those too if you don't w
2009-04-10 by Robert Adsett
David VanHorn wrote: > On Fri, Apr 10, 2009 at 11:29 AM, Robert Adsett > wrote: >> Graham Davies wrote: >> > the diode, present in many MOSFETs from drain to source, >> >> The diode is inevitable in the MOSFET structure isn't it? It can be >> optimized for a particular applicatio
2009-04-10 by David VanHorn
On Fri, Apr 10, 2009 at 11:29 AM, Robert Adsett wrote: > Graham Davies wrote: > > the diode, present in many MOSFETs from drain to source, > > The diode is inevitable in the MOSFET structure isn't it? It can be > optimized for a particular application but not eliminated. There ar
2009-04-10 by Robert Adsett
Graham Davies wrote: > the diode, present in many MOSFETs from drain to source, The diode is inevitable in the MOSFET structure isn't it? It can be optimized for a particular application but not eliminated. In fact I use MOSFET's as diodes in certain applications since they are n
2009-04-10 by Graham Davies
--- In AVR-Chat@yahoogroups.com, Robert Adsett wrote: > > The diode is inevitable in > the MOSFET structure isn't it? No, I don't think so. Diodes between both source and drain and the substrate are usual, but you can get rid of those too if you don't want them (in the extreme ca
2009-04-10 by Roy E. Burrage
I don't like it. This scheme may work most of the time, but I agree that we can't guarantee it will work when the drain is pulled low. I come from an old school that states we should never count on active component characteristics that vary widely, that we should use the active c
2009-04-09 by Jonathan King
On Wed, Apr 8, 2009 at 1:22 PM, Graham Davies wrote: > > My question for the non-"digital only" folk is this ... will just about any > MOSFET (with an appropriate threshold) perform well in this circuit? I > understand that the beginner-level textbook structure of a MOSFET is > s
2009-04-09 by Steve Hodge
It's going ok, thanks, but it's currently stalled waiting for a pcb to be made. I'm going to give I2C a try; switching to RS485 (which I do use for other, longer-distance communication) adds complexity and other disadvantages that I'd prefer to avoid if possible. It will be the b
2009-04-09 by Graham Davies
--- In AVR-Chat@yahoogroups.com, "Steve Hodge" wrote: > > ... Phillips App Note AN97055 ... Yes, I think this is the canonical reference for this type of level translator. The description of the operation again states that the MOSFET will turn on when the source is pulled below t
2009-04-09 by Graham Davies
--- In AVR-Chat@yahoogroups.com, "Mike Perks" wrote: > > To answer your question I googled the following paper: > http://www.vartists.com/engineering/N-MOSFET_bidirectional_level_shifter\ > _analysis.pdf That's an interesting paper for anyone not familiar with the circuit, but I
2009-04-09 by Graham Davies
--- In AVR-Chat@yahoogroups.com, "Steve Hodge" wrote: > > Isn't that what a PCA9517 ... does No, not at all. I think Brian is telling you to use differential signaling without understanding the I2C bus. However, it turns out that the PCA9517 is a solution to the problem I describ
2009-04-09 by Brian
Sorry. it been a while. In your original post, you were going to use it incase the distance was great. I was saying, using a diff driver on the parent board and a reciever on the child board regardless of distance would be better. Even short distances without a diff driver can ca
2009-04-08 by David VanHorn
> You can determine if your device is among those that act this way by checking the datasheet description of the register containing the watchdog enable bit. Where it gives the "initial value" you'll see either "0" or "X" where the latter means that the bit is not cleared in resp
2009-04-08 by Don Kinzer
--- In AVR-Chat@yahoogroups.com, David VanHorn wrote: > Do a build and run, or reset, and notice that the WDE > bit is on at reset. It is worth noting that on many (perhaps all) newer devices, the WDE bit is not affected by reset, no matter the source. Once you turn it on it stay
2009-04-08 by David VanHorn
> Switching back to JTAG Ice Mk2 "FIXED" all my problems........ > Not saying that you are as crazy as me but.. No. I'm definitely in the emulator. I've switched over to sim to verify that my WDT code works, which it does. The emulator is loosing control of the target frequently,
2009-04-08 by John Samperi
At 01:03 AM 9/04/2009, you wrote: >Even more fun.. The craziest thing that happened to me this week with the JTAG Ice Mk2 is that the new code would NOT upload into the chip, the old code kept on running happily for a good half hour. This was working code (yep in C...). The embar
2009-04-08 by wagnerj@proaxis.com
> --- In AVR-Chat@yahoogroups.com, "Roy E. Burrage" wrote: >> Since this comes up from time to time on the list: >> http://focus.ti.com/lit/an/scea040/scea040.pdf > > I took a quick look at this, since I have a logic level translation > problem in a product under development. My
2009-04-08 by Mike Perks
I agree with your first post. I didn't find the TI white paper very useful. The FET switch discussion using the CB3T bus switch lead to a dead end in terms of useful ICs that could do the job. > I think the only logic level translation problem that doesn't have a number of straig
2009-04-08 by Graham Davies
--- In AVR-Chat@yahoogroups.com, "Roy E. Burrage" wrote: > ... The intent was to address some > of the issues brought forward by the > occasional digital only folk who > subscribe to this list. OK, there are no other hot threads running right now, so let's chat about this. I thin
2009-04-08 by Roy E. Burrage
I'm sure you're correct, Graham. I didn't look at it thoroughly as it just came through this morning on an EDN blast. Novel? Probably not, for those of us who have been doing this sort of thing for a while. The intent was to address some of the issues brought forward by the occas
2009-04-08 by Graham Davies
--- In AVR-Chat@yahoogroups.com, wagnerj@... wrote: > > You can use the output enable pin of a > [tristate inverter] as a non-inverting > input if you do the "correct thing" > with the normal logic input. Of course, if this has the logic function you require, but this has nothing
2009-04-08 by Roy E. Burrage
Since this comes up from time to time on the list: http://focus.ti.com/lit/an/scea040/scea040.pdf [Non-text portions of this message have been removed]
2009-04-08 by David VanHorn
Yet more fun with tools..I've noticed two new things in the last couple days. 1: WDT always on, even though the chip is NOT programmed for this. Do a build and run, or reset, and notice that the WDE bit is on at reset. Go out of debug, into programming, check the fuses, and WDT a
2009-04-08 by Dave VanHorn
Even more fun.. I decided to trap this condition at boot, and force the WDT off in code. I'm uploading a file, MADWDT.PNG that shows a screen cap. At the first breakpoint, I'd run the code, and let it reset on it's own. The contents of Temp (R24) at that point was 0x00, which say
2009-04-08 by Graham Davies
--- In AVR-Chat@yahoogroups.com, "Roy E. Burrage" wrote: > Since this comes up from time to time on the list: > http://focus.ti.com/lit/an/scea040/scea040.pdf I took a quick look at this, since I have a logic level translation problem in a product under development. My impression
2009-04-01 by Stefan Wimmer
--- In AVR-Chat@yahoogroups.com, "Steve Hodge" wrote: > > Thanks for everyone's input. It's always good to get confirmation! I'll > use one pair for SDA+GND and another for SCL+GND. Or I may substitute V+ > for one GND. working in vehicle electronics (trains) I always cringe when
2009-03-31 by Steve Hodge
Isn't that what a PCA9517 effectively does (among other things)? Steve From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On Behalf Of Brian Sent: Tuesday, March 31, 2009 4:10 PM To: AVR-Chat@yahoogroups.com Subject: [AVR-Chat] Re: i2c and twisted pair Twisted pair
2009-03-31 by Brian
Twisted pair with ground is good. What about diff driver to increase reliability and performance? Brian --- In AVR-Chat@yahoogroups.com, "Steve Hodge" wrote: > > I would like to use standard shielded Cat 5/6 cable to carry I2C signals > between boards, i.e., between microcontroll
2009-03-31 by Steve Hodge
Thanks. I was figuring on 5K, but I'll drop it to 1.2 K. I'm running it at 3.3 V so 1.2 K still keeps the drain slightly under 3 mA, which is another spec isn't it? Or would you choose something else given the 3.3 V? Steve From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogrou
2009-03-31 by Ken Holt
Also, be sure to keep your I2C pullup resistors (Rp) as low as possible, down as far as 1K is allowed by the spec. This will help help your rise-time and speed with that long shield capacitance. Also it may help your noise immunity in that boat-electrical environment. Steve Hodge
2009-03-31 by David VanHorn
On Tue, Mar 31, 2009 at 2:13 PM, Steve Hodge wrote: > Thanks. I'm aware of ground loop issues. My boards always have jumpers to > allow disconnecting ground lines when otherwise there would be multiple > ground connections. Similarly for the shield, so that it can be grounded at
2009-03-31 by Steve Hodge
Thanks. I'm aware of ground loop issues. My boards always have jumpers to allow disconnecting ground lines when otherwise there would be multiple ground connections. Similarly for the shield, so that it can be grounded at only one end. The application is for a boat, which at time
2009-03-31 by David VanHorn
> I have other reasons for wanting to use Cat5: shielding, quick & easy > connect/disconnect, relatively cheap and easy to make up cables, and for my > situation cables that are flexible and easy to run convoluted paths is very > important. I also have other uses for the remainin
2009-03-31 by Steve Hodge
Thanks for everyone's input. It's always good to get confirmation! I'll use one pair for SDA+GND and another for SCL+GND. Or I may substitute V+ for one GND. I have other reasons for wanting to use Cat5: shielding, quick & easy connect/disconnect, relatively cheap and easy to mak
2009-03-31 by David VanHorn
As others have indicated, you want to go with signal and ground in a pair. Putting two signals on a pair will cause large crosstalk. I don't see why this won't work, but be prepared to insert some series resistance in the driving end, maybe 100 ohms or so, to cut down on ringing.
2009-03-31 by Tim Gilbert
You are correct that twisted pair will only help if you're running a differential signal. In fact, running SDA and SCL on the same pair could, in theory, make the signal worse. Why bother with Cat5? I'd probably use a ribbon cable. You can tie every other conductor to ground if i
2009-03-31 by John Samperi
At 12:04 PM 31/03/2009, you wrote: >So now I'm thinking they should be on separate twisted pairs. Perhaps with >GND as the other half of each pair. That would be my choice and have in fact done something similar except that I used 1 wire as V+. ie only used 2 pair. Regards John S
2009-03-31 by Steve Hodge
I would like to use standard shielded Cat 5/6 cable to carry I2C signals between boards, i.e., between microcontrollers on separate boards. Distances are not the question here, because if they end up a factor I'll just use a PCA9517 buffer or something similar, but should someone
2009-03-30 by Brian
I set the following: GICR = 0x40; //for int0 MCUCR = 0x01; //int for logic change //enable global int #asm ("sei") Not sure how to verify if everything is set. Still working with/learning the Studio4 debugger. Brian --- In AVR-Chat@yahoogroups.com, "s.holder123@..." wrote: > > Ho
2009-03-30 by Brian
The mega16 does have level change for int0, page 67. I haven't come across anything that says this is not true. I'll have to look at my code better. Brian --- In AVR-Chat@yahoogroups.com, "stevech11" wrote: > > I hope I'm mistaken, but I recall that the older mega's lacked the "p
2009-03-30 by s.holder123@btinternet.com
How are you writing to the MCUCR ? the default setting for the interrupt pins is low level detect (iscx1 = 0, iscx0 = 0), sounds like you are not actually setting the required value in the MCUCR, can you verify that the value is as you think it is. Regards --- In AVR-Chat@yahoogr
2009-03-30 by stevech11
I hope I'm mistaken, but I recall that the older mega's lacked the "pin change" interrupt capability. This has a register where you enable interrupts for a change in state on a given pin. Look at the PCICR register explanation for the mega168. I don't think the mega16 has that. -
2009-03-30 by David VanHorn
On Sun, Mar 29, 2009 at 6:07 PM, s.holder123@btinternet.com wrote: > I notice that just before the crash you are setting the device pinb5 to an output pin, is the pull up enabled when set as an input ? > > Might be an idea to insert an intermediate state, might possibly be gettin
2009-03-30 by Brian
I have asked this on the codevision site also but wondering if anyone here could help. I am using a mega16 Int 0 with an encoder, no sleep, WDT or other special items. For each detent of the encoder the input to the int 0 goes from 5 - 0.5 - 5 - 0.5 and so on, like it is designed
2009-03-29 by David VanHorn
On Sun, Mar 29, 2009 at 5:48 PM, Jim Wagner wrote: > Hmmm. ... > > Can you set a "variable watch" that triggers on a memory value that > should not change but IS getting changed? I don't remember if Studio > has that. I have that in code, no triggers. > Another possibility is tha