Best way to interface multiple signals from Laptop to a sensors, ADC etc? - Page 1
Forum section: electronics / general

author: abhaymv
author_rank: Contributor
timestamp: September 01, 2013, 06:05:45 pm
content: Hey,In my final year project I need the data from a temperature (LM35), voltage and current sensors transferred to my laptop. The temperature sensor data would be taken at regular intervals as it is a part of temperature control mechanism. The Voltage and current readings will be converted to digital data by an ADC. (For the record, the V and I values are sampled from a charging capacitor used to find the VI charecteristics of a solar cell).I also need to output a PWM waveform to drive LEDs (HV9910) and another PWM to control a peltier element.My Laptop has 2 USB ports, 1 Ethernet and 1 Audio port. (Ofcourse, there is the VGA port, but that's useless here isn't it?)I'm trying to do all the interfacing withMATLAB.Would I need to use another programming language? (Like C? C++?)What's the best way to doall of this at the same time? Would I need a microcontroller at all? Can I generate and transmit a PWM from my laptop (Will a stream of bits work?)?I was thinking serial communication (USB->Serial) with a 74153 MUX... Will it work? I'm a bit new with this...

author: Skimask
author_rank: Super Contributor
timestamp: September 01, 2013, 08:01:56 pm
content: Part 1Quote from: abhaymv on September 01, 2013, 06:05:45 pmPart 2Quote

author: TopLoser
author_rank: Unknown
timestamp: September 01, 2013, 08:56:38 pm
content: http://labjack.com/ue9I'll sell you one cheap as well!

author: kripton2035
author_rank: Super Contributor
timestamp: September 01, 2013, 09:23:41 pm
content: take a look here :http://www.tuxgraphics.org/electronics/200906/home-climate-control.shtmland modify a little the device to add voltage and current measurment and you're in.you can buy the board for 43 euros...regards,

author: Paul Price
author_rank: Super Contributor
timestamp: September 02, 2013, 12:46:47 pm
content: https://www.google.dk/search?q=usb+to+parallel+port+converter+circuit&client=firefox-a&hs=m1U&sa=X&rls=org.mozilla:en-US:official&channel=fflb&tbm=isch&tbo=u&source=univ&ei=OogkUt3kK4GctQa0qYCACw&ved=0CD8QsAQ&biw=1280&bih=861Don't spend US $500 when you can get USB to parallel I/O for $20http://numato.com/8-channel-usb-gpio-moduleMyself, I got a free older laptop that has a standard parallel port and I use it for fast bi-directional I/O between a PC and the external world using QBasic or Visual Basic with a free downloadable driver.Old slow laptops or Desktop PC's make fast and almost free in cost serial or parallel port I/O connections to the real world.

author: Stonent
author_rank: Super Contributor
timestamp: September 02, 2013, 02:14:05 pm
content: Quote from: Skimask on September 01, 2013, 08:01:56 pm

author: abhaymv
author_rank: Contributor
timestamp: September 02, 2013, 04:37:06 pm
content: Quote from: Stonent on September 02, 2013, 02:14:05 pmAlright. So I haven't had the need to interface multiple signals before. We all have to start somewhere...I was thinking of modifying an old model USB data cable for mobiles to get my serial lines. Not the new types, but the ones that have ICs in them...

author: Bored@Work
author_rank: Super Contributor
timestamp: September 02, 2013, 04:59:00 pm
content: Quote from: abhaymv on September 02, 2013, 04:37:06 pmThe point is that you should have learned in the last few years how to acquire the skills you need. And asking people on the Internet to do your work is not the way how it is done. You should also have learned how to extrapolate from a single case and how to combine individual solutions into more complex solutions. Copy-past is not engineering.

author: abhaymv
author_rank: Contributor
timestamp: September 02, 2013, 05:05:34 pm
content: Quote from: Bored@Work on September 02, 2013, 04:59:00 pmWhat should one do when my course does not focus on interfacing? The interfacing I've done was out-of-course. If I were just following the lab sessions, I wouldn't know that either. I have tried reading up on this, but without practical knowledge, there will be confusion on which route to take...Its electronics with telecommunication, so that's probably the reason much focus was not given to the subject. I'm sorry if this is bothersome to you.

author: krish2487
author_rank: Frequent Contributor
timestamp: September 02, 2013, 06:59:43 pm
content: QuoteThe point everyone is trying to make is this :-If your interest and need to learn is purely dependant on your need to get good grades then you are in the wrong forum.Period.All the members here are united by their interests, not their professions. Consequently, the heterogenous mixture of such dissciplines allows others to learn, acquire and hone a skill, NOT GET READYMADE ANSWERS FOR THE FINAL YEAR PROJECT.Asking someone vaguely on the internet to guide you for your final year project will earn contempt and disapproval at best.You should havelearnthow to do your work yourself, not give excuses for your lecturers/ curriculum inability.And please stop posting such absurd nonsense on this forum after repeated ( and some very blatant) hints.

author: Skimask
author_rank: Super Contributor
timestamp: September 02, 2013, 08:27:15 pm
content: Yep, that's what I'm getting at.Seems like the bulk of the "college graduates" only know exactly what was taught in the classes/lectures/etc.Lack the ability to learn, only have the ability to repeat.A complete lack of ability to think outside the box.

author: Paul Price
author_rank: Super Contributor
timestamp: September 02, 2013, 09:00:29 pm
content: Seems like the bulk of the "college graduates" only know exactly what was taught in the classes/lectures/etc.Lack the ability to learn, only have the ability to repeat.A complete lack of ability to think outside the box.What college, what university, turns out graduates like this?To find the answer to this OP's question, one only had to type a few words into Google, as I did for him. Shouldn't a college education at least resulted in a student knowing how to use a web search engine to get answers to his problem. One would expect this skill would have been acquired by the time a student becomes an undergraduate of an elementary school.Seems like a complete inability to think even inside the box.

author: free_electron
author_rank: Super Contributor
timestamp: September 02, 2013, 10:20:52 pm
content: Quote from: Skimask on September 01, 2013, 08:01:56 pmWhat is even worse is that driving 2 pwm's, reading two voltages and an lm35 is something an 8 year old (elementary school level) with an arduino could do in half an hour .... And it would communicate over usb as well...Sad... Very sad... A waste of an education.Note that this is not direct critiscism toward abhaymv ! It is critiscism towards the education he follows.- Either the level of education is total crap where they do nothing but the most elementary stuff ,- or it is a non electronics education , but them why this graduation work ?- or it so uninspiring that the student doesnt get motivated to do stuff on his ownUsb cables and a ttl shift register ? Absolutely no clue what usb is or how it works. And this a telecommunications course ? Sheesh.. Ah wait. Tele .. That means distance... I guess smoke signals count as distance communication...With the given education the best you could do is make the matlab program and use variable names that will be 'populated' with live data. And come up with a block diagram of the hardware needed. The base electronics knowledge is simply not there. So yes, he did the right thing tapping into a forum trying to help with the bit he doesn't know. Nothing wrong with going to seek help.So ,in essence i have given the solution. Get a cheap arduino board. They all have usb. The dev environment is free and it has multiple pwms and analog and digtal inputs.So that solves that problem. It'll jumpstart the project and bridge the knowledge gap( note : it bridges the gap , it does not close the gap ! There is a difference. Closing the gap gives you the knownow to do it yourself, bridging it lets you sidestep and move on. In this case , given timepressure, closing the gap is not possible. You should yell at your teachers and educational onstitute why they let the gap be that wide...)Now, try to work out the signal conditioning you will need (bringing you voltage and current and temperature into signals that can be read by the analog inputs). And them figure out what you need to put behind the pwm generators to drive the peltier. You need abit of electronics there.When you think you got it figured out ,post it so we can take a peek to see if it is right.

author: marshallh
author_rank: Unknown
timestamp: September 02, 2013, 10:49:10 pm
content: I have bad news for you, OP

author: tszaboo
author_rank: Super Contributor
timestamp: September 12, 2013, 06:43:24 pm
content: I totally understand the OP. I came from an Uni, where education meant math, and more math. They were more eager to paste in my head the exponential characteristics of the transistor, than show me one in TO-92 package. Some students never really accomplished anything practical until final year. I was lucky, that I bought my first microcontroller, when I was 17, and acquired some basic know-how, before the brainwashing started.So I also suggest to buy an Arduino. Or better, some breadboard and DIP package PIC16 or Atmega. And start having fun already.