Would you buy this Logic Meter? - Page 1
Forum section: electronics / projects

author: rea5245
author_rank: Frequent Contributor
timestamp: April 29, 2022, 07:01:01 pm
content: A year ago, I made a gadget I call a Logic Meter. It resembles a handheld multimeter but its functions are targeted at microcontroller-based projects.It uses a multimeter-like UI for ease of use. Its features include a UART monitor (with auto baud detect), an SPI monitor, a UART source of canned data, a servo pulse generator, a PWM generator, a GPS simulator (you can generate NMEA sentences for any location and time), and a low-end logic analyzer.The idea is not to be a full-featured logic analyzer. The idea is to take certain tasks that you frequently do, and be able to do them with just the turn of a knob, instead of connecting a device to a PC, running an app, and configuring pins.E.g. I'm frequently in need of monitoring a UART's output, like for reading logging messages. So there's a UART input feature available with just a turn of the knob. And since I often don't know the baud rate, it defaults to auto-detect. I also often want to test whether my code is receiving UART input. So turn the knob a press a button to just send the printable ASCII characters. It doesn't matter if my code considers it garbage; I just want to see if my code is receiving anything. I'm frequently working with GPSs. I want to test conditions like whether the code handles time zones and daylight saving time transitions. Thus, a GPS simulator: turn the knob and set a time and place. And I frequently want to know if a digital signal is active. Forget about whether the signal is doing the right thing ... is it even doing ANYTHING? Thus, a three pin quick and simple "logic analyzer": turn the knob and see if it's a flat line on not.I think it's a cool idea, but maybe it's just me.So I'd like to do a little market research. If something like this existed, would you buy it? How much would you be willing to pay? What do you like/not like about the idea?Here's my demo video. It's 30 minutes long, but the last 10 minutes are a teardown and a description of the software that you don't really need to watch. And I try to move quickly through the demo. Start watching, and you think you've seen enough... stop. ;-)https://youtu.be/55UjsmX5F90

author: tggzzz
author_rank: Super Contributor
timestamp: April 29, 2022, 07:25:32 pm
content: You need a 30s "elevator pitch", that would tell me enough that I might feel it worth spending 30mins of my remaining life thinking about your idea.

author: rea5245
author_rank: Frequent Contributor
timestamp: April 29, 2022, 07:32:30 pm
content: Quote from: tggzzz on April 29, 2022, 07:25:32 pmFair enough. I've edited my original post. I hope it helps.

author: ataradov
author_rank: Super Contributor
timestamp: April 29, 2022, 08:23:51 pm
content: Quote from: rea5245 on April 29, 2022, 07:01:01 pmNo. Combined tools like this are always limited in usability. Usually they would be considered fine for use in the field, but for the desktop use, dedicated tools are much better.Quick UART monitor may be good to have, but eventually you would like to save the output for reference when debugging, or to capture the reported error, for example. And then you may need to send some data too and if you have to download that to the device first, then what is the point? Dedicated USB to UART adapter does not take much space and provides way better functionality.Dedicated tools are just better and more flexible.And for other tings it is easier to come up with dedicated tools as you go, or make things using dev kits or generic breakout boards.For other protocols, I have this toolhttps://github.com/ataradov/dgw, for example. It just provides an interface to the PC, where it is much easier to implement any logic you like and quickly change it as needed for the project.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: April 29, 2022, 08:29:17 pm
content: Nope.For measurements a Logic Analyzer with a big PC screen and comfortable mouse operation is hard to beat. Especially because Sigrok / Pulseview is available as open source and it has some 100+ software decoders for lots of signals.I have a thorough dislike for the hobby servo's, It's a backwards arsed protocol with very low resolution that's almost impossible to use for anything useful.Of other signals that can be generated from a uC, probably it's just easier to stick a uC on a breadboard and write some lines of code to generate some PWM USART strings or other stuff.I also think that the bus pirate does this sort of thing, but it uses a PIC and I do not use those uC's.You also seem to be aiming for a small portable device, while I guess that typical use is probably on the bench in the lab, and size is not such a big concern, but a better ui with more knobs and displays is probably preferable (but also make it bigger)

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: April 29, 2022, 10:43:48 pm
content: Were you trying to remake the Logic Dart?https://www.keysight.com/ca/en/product/E2310A/advanced-logic-probe.htmlNo one wanted one then either. I don't know why. I still want one, just not for the prices on eBay...

author: rea5245
author_rank: Frequent Contributor
timestamp: April 29, 2022, 10:48:27 pm
content: Quote from: Alex Eisenhut on April 29, 2022, 10:43:48 pmI was not aware of the Logic Dart when I started on my Logic Meter.I wanted something that was quicker to set up than a logic analyzer (even the USB ones that connect to a PC). In my experience, I succeeded: for certain tasks, I just connect wires and turn the knob.

author: wizard69
author_rank: Super Contributor
timestamp: April 30, 2022, 02:10:15 am
content: Quote from: rea5245 on April 29, 2022, 07:01:01 pmI probably wouldn't be interested if it is as limited as I imagine.QuoteIf I might I will tell you what my job was/is, which is automation in a manufacturing plant. Some of the capability you describe would be very useful in a small device, that is portable field use. The problem is I''d rather have a programmable device, possibly a table or cell phone format with a built in DMM.QuoteHonestly I wish Fluke would pull head from the sand and come up with a truly modern DMM replacement. These days you often need to lug a whole tool box full of electronics to address a problem in the field.QuoteMaybe! My vision of a similar solution that melds multiple devices into a tablet type device.QuoteProbably the same as a higher end Apple iPad. The only thing is it can't be locked up the way iPad is.An of the top of my head feature list:Must run Linux and be totally open software wise.Must have multiple USB ports to plug various protocol dongles and such into.Must support DMM functions and it must be easy to access the data coming from the DMM. The DMM must be isolated of course.Must support WiFi and cellular networking wouldn't hurt either.Rugged. Obviously for field use the device should be nearly bullet proofIt would be ideal to have multi channel scope functionality again with isolated inputs. In my case bandwidth doesn't have to be amazing but simultaneous sampling on the supported channels would be goodAn array of environmental input sensors that are always available. At the vary least temperature, air pressure and humidity sensing.QuoteLimited band width, maybe later with the movie.

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 30, 2022, 02:05:16 pm
content: Just take the (classic) "Bus Pirate" design and replace the USB to UART chip with a Bluetooth to UART chip. Then write an Android app for it.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: April 30, 2022, 10:05:42 pm
content: I just remembered, maybe yo like the Gabotronics Xprotolab:https://www.gabotronics.com/products/oscilloscopes/xmega-xprotolab

author: rea5245
author_rank: Frequent Contributor
timestamp: April 30, 2022, 10:10:54 pm
content: Quote from: Doctorandus_P on April 30, 2022, 10:05:42 pmMy goal with the Logic Meter is not to make something small; it's to make something easy to use.For the tasks that the LM does, it's dead simple to set up. You just turn the knob. It's easier and faster than plugging a device into a PC, running an app, and configuring the app to do the specific task.For me, it's worked out great. But it seems not to appeal to others.

author: james_s
author_rank: Super Contributor
timestamp: April 30, 2022, 11:06:46 pm
content: Quote from: Doctorandus_P on April 29, 2022, 08:29:17 pmIt made sense in the early 70s when it was developed, and it is still quite useful for the intended purpose. I have quite a few RC airplanes that all use standard servos and for that the PWM interface works just fine.

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: May 02, 2022, 01:05:33 am
content: I would not say that your idea is completely out of the world. As Alex Eisenhut said, that is a product category which a very reputable company tried to fill. And I would not fall for the same ideas as wizard69, as he was asking for about everything in instruments that he needs in one package.As someone who often had to do non-trivial and intrusive testing away from a bench or lab, I could find uses for a dedicated 'logic multimeter'. And yet, your idea has some way to go..Some thoughts on such an instrument:1.) It needs more signals/channels. 4 might work, but I would rather go for 8.2.) It would need a very sophisticated design for the input circuit in order to be both fast and robust enough. Logic thresholds need to be programmable, preferably over a very wide range. Imagine someone who wants to look at a parallel interface between an absolute rotary encoder and a PLC. Or a output from a PLC. There you have 24V logic, while inside a circuit you should be able to work with modern low-volt logic series.3.) add a dedicated trigger signal output (BNC), so that the device could work as a word recognizer probe for non-MSO oscilloscopes or whatever.4.) Looking at UART data by itself is (IMO) not very useful, if you do not have the possibility to set a condition which freezes the output and/or stores data. Also, you just display all data like it came in continuously. There is a need tor timestamping. Also, display format should be selectable. Also useful would be a loopback function.And the really useful thing would be to monitor BOTH channels of a serial communication, while fulfilling the previously mentioned functions.5.) concerning the UI, I would use a dedicated up/down control at the side of the display for scrolling etc. Maybe a wheel or a switch with two detents per direction. Then add a hex keyboard (+clear/enter) below the mode switch.6.) The logic analyser needs much more functionality to be of any relevance. Timing between signals, pulse width, occurence of certain overlaps etc.7.) If you want someone to take this up commecially, you have to think about a market. If you think of a mobile test aid for professional electronics, discard the servo thing outright. Add I²C. One possible baseline here is to look at the functions of serial testers and make one which can cope with all usual interfaces without additional converters. But then most users would want the mostly used connectors in the right pinout. But that could be a dumb part connected over the signal interface connector as an add-on box.8.) The GPS simulator is not a bad idea, given how many applications use GPS for timing and/or location reference. You would have to include the 1PPS pulse, although. And make some arrangements to select/deselect sequences and introduce common error conditions (for example, number of satellites suddenly dropping).Now those are only partial, unconnected functions and ideas which would have to be integrated anew. I think that it is very likely that you would need a faster processing capability, which could be a µP/FPGA combination. But of course, this drives up complexity and power demand.And even for the instrument outlined, I can't guarantee that someone would take it up. I have seen fine ideas to be ignored and left to die, from hand tools to software products. Then youwould have been right to base it on your own needs, so that at least your time and energy isn't lost.BTW, I own a HP Logic Dart and would miss it. While it is far from the outlined device, it is much more than a simple logic probe. It did help me several times.

author: rea5245
author_rank: Frequent Contributor
timestamp: May 02, 2022, 01:54:35 am
content: I'd like to thank everyone for their responses.I think I might not have communicated the use cases for this gadget very well.I'm not trying to make a general-purpose product. I'm not trying to put a logic analyzer into a handheld package.Instead, I wanted to take tasks that I do frequently, and make a tool that is quickly configured (with a turn of the knob) to do those tasks.I'm frequently in need of monitoring a UART's output, like for reading logging messages. So there's a UART feature. And since I often don't know the baud rate, it defaults to auto-detect. Yes, logic analyzers can do it and Bus Pirates can do it. But this is configured to do that task faster.I also often want to test whether my code is receiving UART input. So my logic analyzer has a quick and easy way to just send the printable ASCII characters. It doesn't matter if my code considers it garbage; I just want to see if my code is receiving anything.I'm frequently working with GPSs. I want to test conditions like whether the code handles time zones and daylight saving time transitions. Thus, the GPS simulator.I frequently want to know if a digital signal is active. Forget about whether the signal is doing the right thing ... is it even doing ANYTHING? Thus, a three pin quick and simple "logic analyzer".Are there things you find yourself doing over and over? Would it be nice to have a fast way to do them? I.e. something faster than dragging out a USB analyzer, connecting it to the computer, running the app, and configuring the pins? How about having a gadget where you just turn the knob and go?- Bob

author: ataradov
author_rank: Super Contributor
timestamp: May 02, 2022, 02:13:33 am
content: Quote from: rea5245 on May 02, 2022, 01:54:35 amYes, and I have a lot of tools I made for myself. But I don't have any expectation of them being useful for others, and I don't expect them to be marketable.Quote from: rea5245 on May 02, 2022, 01:54:35 amIf the UI is limited to a knob, the functionality would be similarly limited.Even when generating NMEA data, what if I want to emulate movement? What if I want to test specific time? You may never need that, and this is fine, but you must see that this is a limiting factor for a general purpose tool you try to sell to others.

author: rea5245
author_rank: Frequent Contributor
timestamp: May 02, 2022, 02:18:40 am
content: Quote from: ataradov on May 02, 2022, 02:13:33 amMy logic meter also has 5 buttons that are used for tweaking the functions. In the case of the GPS simulator, they allow you to change the location and time. I show that in the demo video. Yeah, once you start doing that, it's not as easy as turning a knob. But it's still pretty darn easy.- Bob

author: free_electron
author_rank: Super Contributor
timestamp: May 02, 2022, 05:26:35 am
content: - more channels (8 digital out , 8 digital in)- spi and i2c sniffers with read(sniff) and write ability. for i2c : bus scan for slaves)- digital pattern generator in sync with digital input- touchscreen keyboard for uart : be able to type messages and use as simple terminal (vt52/ vt100 emulation)- at least 2 analog inputs, prefer 4. ( two ranges. 0..1 volt and 0 .. 10 volt ) with long term recording ( 10/100/1k/10k samples/second, 10 bit a/d and DEEP memory. 1 megasample per channel minimum) . not intended as oscilloscope, just a chart plotter- thermocouple interface (routable as extra channel to plotter)i would ditch the local user interface and set up a bluetooth link driven from an app. your hardware would be a recording/playback to and from a large buffer. a small fpga combined with lots of ram could do the work.app developed with b4x so it can run on iphone , android , pc , macthe hardware would be universal and abilties only limited to creativity on the frontend.

author: markhen
author_rank: Regular Contributor
timestamp: May 02, 2022, 09:15:46 pm
content: Bob - I applaud you taking the time to build this tool, and to share it with the community - thank you!Putting functions you do often into a compact and usable "grab and go" tool totally makes sense. It also makes sense that others, who don't perhaps have the same recurrent needs, might not be as enthusiastic.As wizard69 said:"come up with a truly modern DMM replacement. These days you often need to lug a whole tool box full of electronics to address a problem in the field"Totally agreed! So we (the community) must continue thinking and trying to innovate in the tool space!!!We all use DMMs regularly, even though a scope/buspirate/PC/sound card etc. can be configured to measure V, I, R !! So let's keep working on ideas for tools that just might be something like "a truly modern DMM replacement"!!!Cheers -Mark

author: thm_w
author_rank: Super Contributor
timestamp: May 02, 2022, 10:11:41 pm
content: OPs github:https://github.com/galacticstudios/Logic-MeterThey mention i2c and a few other things there.