What handy 'gadgets' could you use?

[JackP]

  First of all, I'd like to apologise for the uninformative title - I had too much info to cram in there otherwise! Also, sorry for any double letters or misspelling, my laptop keyboard is acting up ATM. EDIT: I have edited the title to reflect the direction in which I wish this thread to go (AKA my second original query).

  Primarily, I started this thread for some information about a concept I came up with. I appreciate what I like to call uDesign (patent pending  ), or the design of USEFUL products to be as small as reasonably possible. Thus, I was thinking about a system of standalone sensors that could log some environmental (or other) change over time, independently of the main system. The initial image is of small coin cell-powered sensor boards with a connector; after a certain period has elapsed, you retrieve the sensor(s), plug them into the 'motherboard' which handles UART comms, and then see graphs and data for each sensor in a C#/Python interface (both work with UART, just need to figure out which will be easiest and best looking, but I am still open to suggestions of other methods and languages). BTW, I have initially decided against WiFi as it will drive the cost up of every single sensor board, and who knows the range that will be needed?

  So what do you think? Does this idea have commercial validity, and can you see it being useful to some people? And yes, I am designing this to be an exercise in DFM, so things like BOM cost and PCB complexity will matter.

  Another major query I have of you guys is what 'tech' would you find useful to have on you, which has never really been done before (at least in this form factor). I'm not talking smart watches or phones, just simple little things that can make your life just a little bit easier. I ask because I have another idea, closely linked to the one detailed above, about small (keyring, pocket? sized) gadgets which can comfortably be carried around on your person. I use the term 'gadgets' begrudgingly, seeing as so often the word is a synonym of unnecessary and novel. This being the main reason for including this question, so you could give me ideas about what you would find useful (obviously within the bounds of plausibility), whether it links to you specifically as an EE, machinist, IT guy, or whatever, or the general public.

  I apologise for the openness of these queries, but I love the concept so much, yet just haven't quite got that killer idea that I need. And believe me, it been a while since my last project so I need something to sink my teeth into, lest my EE hobby lose its interest for me (anyone else have trouble coming up with actually useful project ideas, seeing as pointless pursuits do not give me the same driving force as a decent, solid goal?). I am also aware that there are many different questions presented in this thread, so I would be grateful if you could answer even one of these.

  Thank you for taking the time to read this.

[Fsck]

you mean like a modular, compartmentalized, more specific sensordrone?
http://sensorcon.com/products/sensordrone-multisensor-tool

I feel like it'd be a grand endeavor to get decent coverage, you typically use a couple of sensors at once depending on what exactly you're monitoring and you end up rolling them all into one unit.

what'd be really great is if you can connect a bunch of them together to have them log multiple parameters simultaneously.

[funkathustra]

I was thinking about a system of standalone sensors that could log some environmental (or other) change over time, independently of the main system. The initial image is of small coin cell-powered sensor boards with a connector; after a certain period has elapsed, you retrieve the sensor(s), plug them into the 'motherboard' which handles UART comms, and then see graphs and data for each sensor in a C#/Python interface

Why on earth would anyone want this? What is the intended application?

Why do I have to retrieve the data off the sensor manually? It should be wireless -- preferably BTLE so it can pair with my phone when in range.

The nrf51822 is less than $2 in quantity, and sleeps at 500 nA. Done.

[JackP]

The intention was to place the sensors for an extended period, and then collect the results into one database on the program, which could be viewed graphically. Essentially, a time correlated (RTC) environmental datalogging system. I just thought for a low price point, people may be interested in examining their environ, and it could be useful in some situations (for example, a greenhouse or even just an office space).

Fsck, my idea was to have multiple sensors, which could then log data simultaneously. But this idea offers flexibility with the individual modules.

Anyway, criticism noted and I will consider adapting the design. Still interested in the other question about 'pocket tech'. What are the benefits of logging data locally Vs. connecting to a PC or control unit wirelessly, taking into account range, cost...?
Thanks a lot guys.

[Kalvin]

If you want to have the lowest BOM, select the lowest cost microcontroller, SPI FLASH for data storage and other components that get the job done. Typically you will spend more time in developing due to the constrained microcontroller and trying to squeeze everything into a smallest possible PCB.

If you want to make your life a bit easier, there are some nice microcontrollers in $2 - $3 range that are quite painless to program in C, has decent amount of Flash for the program and RAM, has on-chip RC oscillator for the CPU clock, has on-chip RTCC (needs 32kHz external crystal) which can wake the processor periodically, has on-chip 12-bit ADC for the measurements, and are targeted for low power applications running from a single coin cell down to 1.8V (typical current consumption is below 1uA when the RTCC is running and the processor is stopped). For example the Microchip's 16-bit PIC24F and the Cypress's 32-bit ARM PSoC4 are such families. There are even on-chip op amps that might become handy when interfacing to sensors. Of course, other manufacturers will have quite similar microcontrollers available.

[JackP]

Thanks for that Kalvin.

  I now have a decent basis to start work on the implementation of the sensor system. However, this will likely end up as a long-running project, so I'd like to have an immediate goal. As such, I'm still interested in designing a small system of 'pocketable' tech, running off standard coin cells (CR2032, or rechargeable variant?). I guess it seems like I'm clinging to a solution without having established a problem, but low power, small scale design interests me.

  So the question is: what little 'gadgets' (see above for quotation marks) could be handy for you in day-to-day life? Whether relatively complex, or just a simple 'life hack', I'm really interested to research how small bits of tech can influence a person's lifestyle. Literally anything you could use, it would be great to hear from you. I'm having a complete mind blank, and need a goal over the summer holidays, so any help you can give is much appreciated.

Thanks again.