Newbie on the block

Discussion in 'The Projects Forum' started by theripley, Apr 22, 2013.

  1. theripley

    Thread Starter New Member

    Apr 22, 2013
    3
    0
    Hi. Good day.

    I am a newbie on this forum. My experience is more on system integration using PLC, not PIC. I got interested in PIC as I wanted to put up/ make a new business opportunity for our company, I mean, for the company that I am working with. This project is a data logger, measuring & data saving RH & temperature.

    With this, I would like to seek advice as to what should my first steps be in acquiring necessary skills? What references should I read? What materials should I buy?

    Please help me:)
     
  2. Meixner

    Member

    Sep 26, 2011
    116
    21
    What skolls do you already have.
     
  3. panic mode

    Senior Member

    Oct 10, 2011
    1,318
    304
    introduction was ok so welcome to the forum

    i would start with writing down specs like
    - size of each sample (8bit, 16 bit, 32bit)
    - number of samples to be stored
    - sampling period
    - compute memory requirements
    - is it enough to just collect samples or there need to be timestamp (at least recorded at begin, along with sampling period)
    - how to retrieve the data (network, direct connection, memory card with file system)
    - how to bring the sample value into microcontroller
    - how to control it (some PC app as GUI or local interface with LCD and keypad)
    - how to power it and what is expected battery life
    - is there particular external trigger or is it manual one
    etc.


    using RTC (real time clock) and SD card with FAT filesystem seem to work nicely.

    one can quickly swap card and device can continue operation while you get the motherload of data
     
  4. takao21203

    Distinguished Member

    Apr 28, 2012
    3,577
    463
    PIC24F seems to be good these days for a starter.

    There are ready-made developement boards available.

    It is also possible to start with blank chips.

    data logger, measuring & data saving RH & temperature.

    Best for this is a small color TFT, or monochrome GLCD.
    You don't neccessarily need SD cards, serial FLASH is a bit easier to use and cheaper.

    Depends on the data volume.

    How much are you going to invest for the prototype? Or the developement equipment?

    I would not recommend the older 16F series, also 18F are 8bit only.

    Starting up a PIC 24F is not so difficult with the new MPLABX as there are templates. I did recently with a blank chip, and the blink LED program works...wasn't a big effort.

    If you want to do the investment, I think Microchip has demo and evalution boards for the 24F.
     
    theripley likes this.
  5. panic mode

    Senior Member

    Oct 10, 2011
    1,318
    304
    i think there is a picstick also using PIC24, and thee is a book from Reese on Pic24 programming. his website also has tons of code samples.
     
  6. edwardholmes91

    Member

    Feb 25, 2013
    181
    18
    Can I suggest looking at a system like PICAXE, GENIE or Arduino to start with? I have personally had experience in using PICAXE before. They are easy to use and provide lots of support along with their own online communities. The only downside to them is that they do cost slightly more than using a generic PIC.
     
  7. theripley

    Thread Starter New Member

    Apr 22, 2013
    3
    0
    Hi Panic mode. I know you from another forum, PLCS. Here are my answers in bold, red texts.

    There were questions, I haven't answered because I am not sure if I understand the question correctly. I hope I have given enough information.

    Theripley
     
  8. panic mode

    Senior Member

    Oct 10, 2011
    1,318
    304
    hello ripley,

    yes, i frequent several forums, including ones about industrial automation. i guess if i want to hide, i better try different identities ;-)

    sounds like your application is not very demanding, so if you have 700 samples each of T and RH you need only 1.4kb of storage. in this case writing to local flash is an option and usually easier (no need to handle file system, you can just store raw data and send it out via RS232 for example). writing to flash wears it out. this is why writing to external device is in general better option (cards can be easily replaced when needed, otherwise you get brick). this is why flash is organised in small pages (like 200-300 bytes). one option to reduce wear is to buffer data in RAM for part or entire page and then dump it to flash in one write. but one has to be careful not to loose the data if power is interrupted for example. also since the sampling period is so long, you will probably want to spend most of the time in sleep to preserve batteries etc.
     
    theripley likes this.
  9. theripley

    Thread Starter New Member

    Apr 22, 2013
    3
    0
    Takao21203 had suggested using PIC24F to get me started with this application. I think I'll better try that one. This will be the first time that I will try programming PIC. I am pretty excited.
     
  10. panic mode

    Senior Member

    Oct 10, 2011
    1,318
    304
    the product i had in mind is called Microstick
    http://www.reesemicro.com/Home/the-microchip-microstick

    the link above also shows all the code samples. this gives you easy start but you can make your own board and replace ICs as they are socketed.

    technically you can use USB to program the chip (because it contains small bootloader code) but i strongly recommend getting PicKit2 or PicKit3. That way even if you make mistake and your program somehow corrupts bootloader (it happens), you can always flash the chip and start over. but if you have PicKit, you are covered, you can put the bootloader back any time (and load it into any new chips you may want to use) or .... you have a choice and if you like, you don't need to use bootloader at all, just download hex file using pickit.
     
  11. panic mode

    Senior Member

    Oct 10, 2011
    1,318
    304
    nce thing is that these chips have built in PLL and even built in oscillator is stable enough to allow RS232 (over USB) communication, no need for crystal and the 18pF caps. this means that you could use this as a development platform and then move the chip to target board that has only few parts.
     
Loading...