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2007-12-14 by subscriptions@aeolusdevelopment.com
Steven Hodge Wrote >Yes, my application is (sort of) automotive. Specifically it is a boat >environment, which is 12 VDC. My guess is that in some respects it's not >quite as harsh as automotive, but in others, eg, high power RF transmissions >and need to shield magnetic compasse
2007-12-14 by David VanHorn
> Why couldn't you use a N-channel fet at the bottom end of the voltage > divider, with fairly high resistors for the divider? This would save on > mosfets and resistors, and I don't think would draw any power when off > (the AVR's analog inputs are high resistance - 100M accordi
2007-12-14 by Steven Hodge
Ok, OP back again. I was away for most of yesterday. Yes, my application is (sort of) automotive. Specifically it is a boat environment, which is 12 VDC. My guess is that in some respects it's not quite as harsh as automotive, but in others, eg, high power RF transmissions and ne
2007-12-14 by Tim Mitchell
Steven Hodge wrote: > I have used VP3203 enhancement mode P-channel mosfets (actually DMOS > FET's, I just loosely call them mosfets) on PCB's in the past and I > see no reason why one of these, with its gate driven directly by a uC > output pin, could not be used to turn on/off
2007-12-14 by Roy E. Burrage
Why not just stick with MOSFETs, Graham? Use something like a 35 cent TP0610 for the the P-channel FET and a 10 cent 2N7000 for the N-channel FET. Leakage currents at that point would be more than likely a function of board cleanliness than component leakage. Overall circuit curr
2007-12-14 by Graham Davies
--- In AVR-Chat@yahoogroups.com, "Roy E. Burrage" wrote: > Why not just stick with MOSFETs, Graham? Sure. An NPN transistor is just an alternative. > He might also want to use some sort > of gate/source protection scheme ... That would depend on the application, which we don't kn
2007-12-14 by Tim Mitchell
Graham Davies wrote: > --- In AVR-Chat@yahoogroups.com, "Tim Mitchell" wrote: > >> Why couldn't you use a N-channel >> fet at the bottom end of the >> voltage divider, with fairly >> high resistors for the divider? > > The microcontroller analog inputs are now permanently connect
2007-12-14 by Graham Davies
--- In AVR-Chat@yahoogroups.com, "Tim Mitchell" wrote: > Why couldn't you use a N-channel > fet at the bottom end of the > voltage divider, with fairly > high resistors for the divider? The microcontroller analog inputs are now permanently connected to the supplies to be measured
2007-12-14 by Tim Mitchell
Graham Davies wrote: > --- In AVR-Chat@yahoogroups.com, "David VanHorn" > wrote: > >> For this business, you really need >> some software, and some hardware, >> specifically ANALOG! > > Agreed. So, shall we do it? It seems like an interesting problem > and it isn't someone's home
2007-12-14 by David VanHorn
> If a little compexity is acceptable, this could work. You'd have to > figure out exactly where to put the MOSFETS and how to drive their > gates without getting back into the problem you're trying to get out of. This is why people who do software only, have such a hard time wit
2007-12-14 by Graham Davies
--- In AVR-Chat@yahoogroups.com, "David VanHorn" wrote: > For this business, you really need > some software, and some hardware, > specifically ANALOG! Agreed. So, shall we do it? It seems like an interesting problem and it isn't someone's homework. I would use a P-channel enhanc
2007-12-14 by Graham Davies
--- In AVR-Chat@yahoogroups.com, "smhodge" wrote: > ... additional current drains of > the order of what the uC consumes ... Ah, so the question is really how can you monitor a 12 volt source with a low voltage microcontroller while drawing less than a dozen microamps. I'm not su
2007-12-13 by Steven Hodge
Excellent idea on the "expanded scale" thing. Thanks. Steve From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On Behalf Of David Kelly Sent: Thursday, December 13, 2007 11:15 AM To: AVR-Chat@yahoogroups.com Subject: Re: [AVR-Chat] Re: ADC Vref On Thu, Dec 13, 2007
2007-12-13 by Roy E. Burrage
It can be done, Cat C, but must be done with an inverting amplifier in a differential amplifier configuration in order to get the less-than-1 gain. This would necessitate either a dual supply with another inverter with gain following the differential or a reference offset for the
2007-12-13 by David Kelly
On Thu, Dec 13, 2007 at 10:31:38AM -0700, Cat C wrote: > > Why never use gain of less than 1? Stability? Can't that be sorted > out and still use gain of less than 1? With a gain of 1 your feedback current equals your input current. With gain of less than 1 the current through th
2007-12-13 by Cat C
Why never use gain of less than 1? Stability? Can't that be sorted out and still use gain of less than 1? Thanks, Cat > Yes, "subtract", but remember never to use gain of less than 1. If gain > of less than 1 is desired use a gain of 1 to buffer, then drive a > voltage divider.
2007-12-13 by Philippe Habib
I don't think anyone said it was owed. I think he was acknowleging the value of the help he received from those patient and helpful engineers in the past. The measure of being welcoming and helpful is the stuff you do that is not owed. On Dec 12, 2007, at 5:41 PM, Tom Becker wrot
2007-12-13 by David Kelly
On Wed, Dec 12, 2007 at 11:47:55PM -0500, David VanHorn wrote: > > You'll most likely have to use a voltage divider to ensure that your > > analog input voltages remain below the maximum level. > > You can also use an op-amp to subtract X volts from the input signal, > if you do
2007-12-13 by smhodge
--- In AVR-Chat@yahoogroups.com, "Graham Davies" wrote: > > --- In AVR-Chat@yahoogroups.com, "Steven Hodge" > wrote: > > > Can I ... input to Vref a voltage > > reference value equal to the maximum > > of what I need to measure, say 15 V, > > even though that is well above AVcc?
2007-12-13 by smhodge
--- In AVR-Chat@yahoogroups.com, "David VanHorn" wrote: > > > You'll most likely have to use a voltage divider to ensure that your > > analog input voltages remain below the maximum level. > > You can also use an op-amp to subtract X volts from the input signal, > if you do that
2007-12-13 by David VanHorn
> You'll most likely have to use a voltage divider to ensure that your > analog input voltages remain below the maximum level. You can also use an op-amp to subtract X volts from the input signal, if you do that properly. Op-Amps were originally intended as building blocks for an
2007-12-13 by David Kelly
On Wed, Dec 12, 2007 at 02:47:05PM -0700, Dennis Clark wrote: > > Now I'm pretty thick skinned so I could be wrong, but it seems to me > that the majority of folks here are quite friendly but could get > prickly when asked an unanswerable question like "how high is up?", > which
2007-12-13 by Don Kinzer
--- In AVR-Chat@yahoogroups.com, "Steven Hodge" wrote: > In fact, nowhere in the main text of the ADC section of > the data sheet does it explicitly state, or even imply > that Vref cannot be greater than AVcc. Perhaps so. But in the section titled "ADC Characteristics" (way in t
2007-12-13 by Graham Davies
--- In AVR-Chat@yahoogroups.com, "Steven Hodge" wrote: > Can I ... input to Vref a voltage > reference value equal to the maximum > of what I need to measure, say 15 V, > even though that is well above AVcc? No. > Or does the spec "maximum" truly > imply that Vref cannot, under a
2007-12-13 by Tom Becker
--- np np wrote: > ... it's time the old-timers in electronics were a bit more tolerant [] but due to _other_ understanding and patient engineers, I learned. What makes you believe those _others_ were not very-tolerant, understanding and very-, very-patient old-timers who humbly
2007-12-12 by Zack Widup
I would kind of hope that people have some idea of using microcontrollers and some experience writing code when they join this forum. I first wrote code for the Z80 many years ago; that's where I cut my teeth so to speak. I then got interested in the 8051, 8085, MC6800, eventuall
2007-12-12 by Dennis Clark
Tsk tsk. You're talking personalities, not engineers! We come in all shapes and temperaments. That latter is also somewhat determined by the time of day and day of week as well. :) Now I'm pretty thick skinned so I could be wrong, but it seems to me that the majority of folks her
2007-12-12 by np np
I think its time the old timers in electronics were a bit more tolerant to the newbies. There was a time when I didnt understand the basics but due to other understanding and patient engineers I learned. I know on most groups you get the clever clogs or the high and mighty. I wou
2007-12-12 by Steven Hodge
I would like to measure voltages using the ADC on an AVR (ATmega644P specifically), but voltages higher than AVcc. I gather from the data sheet that AVcc cannot be greater than Vcc by more than 0.3 V. I intend to use Vcc = 3.0 V, so that implies AVcc needs to be essentially Vcc.
2007-12-12 by Graham Davies
--- In AVR-Chat@yahoogroups.com, Philippe Habib wrote: > I've only been on this list a > couple of weeks and I have not > found this kind of attitude > from a few people very helpful > or welcoming. There's nothing wrong with this list. This is the way lists are. When you join, y
2007-12-11 by David VanHorn
> I'm still chewing on the pointers I got on my PWM problem so I should get > back to work. My first real hardware arrived yesterday and it doesn't work > so its not like I should be on line anyway. Translated to newbiespeak: "PLZ HELP ME MY NEW HARDWARE DOSENT WORK WHAT CAN I DO
2007-12-11 by Philippe Habib
I didn't mean to suggest that more screening or more evaluation of people's contribution should occur, I just wanted to say that it was the only way I could think of the address the behavior. I understand how much work it can be to start and moderate a group and I am nothing but
2007-12-11 by Roy E. Burrage
What you're asking here, Philippe, is an awful lot of work for the moderators. I'm not one here, but do moderate others and have moderated several over the years. I don't know about the others, but I get a bit frustrated with those who want someone else to do the work for their g
2007-12-11 by Tom Becker
> ... limited to professionals and qualified hobbyists. Does that mean an on-line quiz you have to pass to join? I believe most here and those on similar groups truly enjoy spontaneously helping others when they can. Those who don't, just lurk and are rarely heard and are not a p
2007-12-11 by David VanHorn
> I've been thinking about it and I don't think I have a solution either. I > thought that maybe the group should be limited to professionals and > qualified hobbyists. You're always free to start your own group.. I started AVR-Chat when I got mad at the original AVR mailing list
2007-12-11 by Philippe Habib
I guess that in saying I didn't like the responses without suggesting a fix, I was doing it too. At least no one suggested I was trying to get a solution from others as part of a sociology class. I've been thinking about it and I don't think I have a solution either. I thought th
2007-12-10 by Philippe Habib
On the surface, your algorithm makes sense for what you're doing. As for help writing the code, if you need help with that you need to work on the specific language you're having problems with. I think the purpose of this group is to work out processor specific issues, not genera
2007-12-10 by John Clymer
Nice work. If you have to ask about actual code with a fairly straight forward algorithm like that, then you either need to read your datasheets some more, or hire a programmer. If I assume you have the rest of the program done, then you must be struggling with AVR specific part
2007-12-10 by huiyangdoh
I have come out with the exact schematic and algorithm for DAC program using AD7528. Assume you connect to the following: 1. 8 x bit Data input you can connect to all of Atmega Port D, 2. For CS, DAC A/B & WRITE, you can connect to Port C [pin 0, 1, 2] respectively, For algorithm
2007-12-09 by John Samperi
At 08:18 PM 9/12/2007, you wrote: >11 ports lines of Atmega16 where PortC0-PortC7 >would be input to the 8-bit parallel AD7528 chip If you can avoid the use of portc2-portc5 for the chip, then you will have the JTAG port available for debugging or programming without too much mes
2007-12-09 by John Clymer
D0..7, WR*, DAC1*/DAC2 lines can be shared between the multiple AD7528's. You will need seperate CS* lines for each AD7528, this way you can select which DAC chip you are selecting to write to, all the other control lines can be in common and work together. John C huiyangdoh wrot
2007-12-09 by Roy E. Burrage
Answers to your questions: 1. Yes, you can make these chips comply. The question now is, how much will it cost you. It's only a matter of the depth of your pockets. 2. With wire and solder. Wire wrap if you prefer. You can use a UART, USART, or just plain old gas. 3. Their names,
2007-12-09 by Enki
On 9 Dec 2007 at 15:01, Musab Fakrhi wrote: > Hi > > The query is about RFID , I have RFID tag ( Transponder) Clamshell as > 125Khz ,so: > > 1.chip number U2270B or H4102 could comply with this kind of RFID tag ? > 2.if yes, how can I connect this chip ( IC ) with micro controlle
2007-12-09 by Musab Fakrhi
Hi The query is about RFID , I have RFID tag ( Transponder) Clamshell as 125Khz ,so: 1.chip number U2270B or H4102 could comply with this kind of RFID tag ? 2.if yes, how can I connect this chip ( IC ) with micro controller AVR ? by UART ,maybe? 3.what is difference between ISO 1
2007-12-09 by Roy E. Burrage
It's all in the datasheet. I suggest you look there first and write your code. Then if you have problems getting your code to work you can ask specific questions, maybe post your code and we'll try to help you. Grandpa always told us when we were kids that when you need a hand, l
2007-12-09 by Roy E. Burrage
The '7528 is over 30 years old...1970s technology. I don't remember if it was invented by Precision Monolithics or Analog Devices with PMI as a second source, but it's old technology and if you're developing a product intending to use them you'll eventually have issues trying to
2007-12-09 by huiyangdoh
It is a good suggestion to use MCP4922 since it is cheaper than AD7528 but it is running out of stock over here. I could get AD7528 though. Anyway, can you show me how to interface MCP4922 with Atmega 16 if it were to design 4xDAC and also some of the codes? Regards. --- In AVR-C
2007-12-09 by Roy E. Burrage
You might do better using something like a Microchip MCP4922. It has a serial SPI interface, 12 bit accuracy, 14 pin dip package, dual DAC, and rail to rail outputs for starters. We use the MCP4921 single DAC version here regularly with good results. We have used the '4922 in a c
2007-12-09 by huiyangdoh
Yeah I know. In fact MCP4725 is my first choice but since I couldn't get it from the shop here, I would go with AD7528. So, any suggestion to design the 4X DAC using AD7528 for Atmega16? I crack my mind to search for this topic using Google but to no avail. --- In AVR-Chat@yahoog
2007-12-09 by huiyangdoh
I am trying to develop DAC circuitry for Atmega 16 since Atmega16 doesn't have in-built feature of DAC. The circuitry design will be 4X DAC design using AD7528 DAC Chips. To my understanding,the 4X DAC circuit would be using 11 ports lines of Atmega16 where PortC0-PortC7 would be