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Interface BOE with 4DSystems Display — Parallax Forums

Interface BOE with 4DSystems Display

PridborPridbor Posts: 30
edited 2014-01-22 22:11 in Propeller 1
I'm trying to put a system together using the BOE as a data acquisition system, just a few parameters,
and want to display values of these on one of 4dSystems LCD displays. I have seen that Parallax also offers these
displays, and was wondering if there was somebody who could give me a few hints how best to interface
with one of these.

If possible then I would like to feed 2 displays, serial multi-drop of sorts, and only forward, no duplex communication
with the display

Thanks in advance

Preben

Comments

  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-01-01 23:30
    I've used a couple different 4DSystems displays and don't see why there would be problem using one with a BOE. As long as it's one of the many displays which are controlled by serial commands, the BS2 could just send the needed commands with the serial out statement.

    I think some displays are use 3.3V logic so you would want to make sure the 5V TTL signal from the BS2 wouldn't be a problem (I doubt it would).

    I also don't see a problem with using two displays.
  • PridborPridbor Posts: 30
    edited 2014-01-02 13:18
    Could you please point me to a place where I can find the connector pins for the 2 serial ports?

    I have looked through the misc downloadable docs but can't seem to find an example for
    a simple RS 232 like interface

    Thanks
  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-01-02 14:09
    I've used a display like this with the Propeller. I just used a wire between the two devices to communicate. I was under the impression you could do the same with a Basic Stamp.
  • PridborPridbor Posts: 30
    edited 2014-01-02 16:25
    The Board of Education is a Propeller based module.

    Thanks
  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-01-02 16:45
    Pridbor wrote: »
    The Board of Education is a Propeller based module.

    Thanks

    There is a Propeller Board of Education but in general the words "Board of Education" or "BOE" as in "BOE-Bot" refers to the Basic Stamp version.

    IMO, the Propeller version is way cooler than the BS2 version.

    The main thing to worry about with the display is if you're receiving a signal from the display and the display uses 5V logic, then you'd need to use current limiting resistors on the receiving I/O pin.

    IMO, having a PropBOE makes this a much easier task.

    Which display did you want to use? (A link would help.)
  • PridborPridbor Posts: 30
    edited 2014-01-03 08:34
    I thought that the Basic Stamp was one of the very early simple uCs and not Propeller, but doesn't matter really

    The Display I have chosen is this one: uLCD-32 PTU

    Somehow I couldn't get the ctrl C/V to work here for a direct link (it's too long for me to manually enter :-)

    My plan is to only feed the display data as a dumb terminal, but if I was to change my mind later, could you please
    point me to a diagram of what you mea. E.g is it a voltage divider or a serial resistor, my electronics knowledge
    is a bit rusty

    I should have added that it's for my car, older Citroen, where the old LCD displays are getting very unreliable
    due to their elastomeric connectors, so I can't read them half of the time :-(

    This project is actually more just for the fun of it to keep my mind a bit active and restore/upgrade the car a bit,
    as I'm retired and mostly do my stone sculpting and on and off fiddle with he car.

    I have gone through a lot of the Spin examples, and a number of C programs as well, and I am trying to get
    the C "libraries to work" get an error msg when hitting the include simple libraries, or something like that.

    But that's tonight's problem t be solved :-)

    Thanks for your insight d help!

    Preben
  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-01-03 09:27
    Pridbor wrote: »
    I thought that the Basic Stamp was one of the very early simple uCs and not Propeller,

    Yes, it is/was a very early uC but it's still very popular (despite my best attempts of converting people over to the Propeller).

    There are very many more Basic Stamp versions of the Board of Education (BOE) than there are Propeller Board of Education devices in the world (my guess is the BS2 version still out sells the Prop version).

    The names "Board of Education" (BOE) and "Propeller Board of Education" (PropBOE) are comparable to "sugar" and "brown sugar". If one says "sugar" without "brown" it's assumed to be white sugar. The same goes for the "Board of Education". If "Board of Education" is used without the word "Propeller" or "Prop" it's assumed to be the Basic Stamp version.
    Pridbor wrote: »
    but doesn't matter really

    Yes and no. It can be very helpful when communicating on the forum. But it's not a big deal.

    It just now noticed this thread is in the Propeller forum. That should have been a clue. (I check the forums with the "What's New" button and I don't always pay attention to which forum the post is in.)
    Pridbor wrote: »
    The Display I have chosen is this one: uLCD-32 PTU

    I found this display at SparkFun (Parallax has one too) which I'm guessing is about the same as the one you're thinking of purchasing?
    Pridbor wrote: »
    My plan is to only feed the display data as a dumb terminal, but if I was to change my mind later, could you please
    point me to a diagram of what you mean.

    It looks like the display uses 5V logic so a wire from the Propeller I/O pin (tx) would be connected directly to the display's rx pin. If/when you want to receive information back from the display, you want to make sure there is a resistor between the display and the Propeller's receive pin. This series resistor should be at least 3K. I generally use 10K resistors when receiving 5V signals. A Propeller input pin can tolerate 5V but only at very low currents. The clamping diodes can be damaged if more than 500uA (microamps) pass through them.

    I just realized I linked to a touchscreen display. If you were to use a touchscreen version then you would need to be able to receive data to know where the screen had been touched.

    I didn't see a non-touchscreen version of the display (though I didn't look very hard) so I don't know what the price difference is. It might be worth having a touchscreen even if you don't use now. It could be added once you're ready to add that feature.

    I hope you take pictures of your project to show us how you end up using the display.
  • Beau SchwabeBeau Schwabe Posts: 6,566
    edited 2014-01-03 09:48
    There are a couple of OBEX examples for our Displays that we sell, and they come with a serial cable.

    uOLED-128-G2:
    http://obex.parallax.com/object/718
    Video DEMO:
    http://www.youtube.com/watch?v=8Ou2VjV_3IE



    uLCD(SK)-32PTU Touch Screen
    http://obex.parallax.com/object/722
    Video DEMO:
    http://www.youtube.com/watch?v=gTWvkO_BC3E



    Setup Video instructions for Serial configuration:
    http://www.youtube.com/watch?v=ZIlAoABmQ0w
  • ratronicratronic Posts: 1,451
    edited 2014-01-03 10:01
    Pridbor here is the serial command set.
    pdf
    pdf
    PICASO-SPE-COMMAND-SET-REV1.5.pdf
    3M
  • Don MDon M Posts: 1,652
    edited 2014-01-03 10:16
    I have quite a bit of experience using the 4D display in serial mode connected to a Propeller. I use the 4.3" version with cap touch sensing. You don't need to worry about 3.3v / 5v levels as the displays are actually running on 3.3v internally (display processor) so the serial connection is at 3.3v levels. The displays are fed 5v to operate but there is a voltage regulator on the displays that I use.

    I just use Full Duplex Serial object to communicate with the display. I wrote my own driver object but I see Beau has submitted one to the OBEX that should work fine. You could get by with only sending data to the display however you won't be able to monitor the return messages from the display to indicate any error messages. Some commands take longer than others and if you just send a bunch of data to the display willy nilly without regard to timing you'll tear your hair out wondering why it doesn't show up on the screen. Also if you are usiing a touch version and want to get the "touch" message back from the display you would need a receive seial channel for that.

    You can run multiple instances of FDS and send to different displays. Shouldn't be any problem.

    Hope this helps.
  • PridborPridbor Posts: 30
    edited 2014-01-03 18:59
    Thanks all you have been great help!

    I read through all of the references and watched the videos and I begin to see a few things that I need to consider.

    First of all I did buy the Displays, and several weeks before I purchased the PropBOE, and had I researched well before
    ordering, I would have noticed that I could have got the same display from Parallax. I had my eyes on a Oled display and
    changed my mind while messing around on the 4Dsystems site. Well there's always another time.

    And yes I did end up picking a Display with touch and you are all right in telling me that I will need some feedback. I will dwell a bit on what exactly the role of each of the components will be. I was thinking of either multi-dropping the serial from the Prop to the displays (2) or using the 2 serial interfaces to each a display.

    Now where I fail is to find the proper serial interface connection points on my module. I'm under the impression that there are
    2 serial interfaces on the module, but I haven't been able to find/figure out the pins for these. I assume that one might be the USB connector? I see all kinds of CLS, RTS etc but no Rx, Tx except at 2 LEDs at the PCI connector.

    Thanks again all

    Preben
  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-01-03 19:15
    Are the pins different than what's shown on the picture at SparkFun?

    11677-03.jpg
    It looks like there's a tx and rx in the bottom row of the 2x5 header.
    I think I see "+5V TX RX GND RES".
  • Don MDon M Posts: 1,652
    edited 2014-01-04 03:28
    You would use the same connector that you use to program the display as Duane pointed out.
  • PridborPridbor Posts: 30
    edited 2014-01-04 13:54
    Sorry gents I was alluding to the PropBOE card where I don't find the pins RX/TX.

    The Display pins are nicely marked like Duane indicated with the image.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-01-04 14:37
    Pridbor wrote: »
    Sorry gents I was alluding to the PropBOE card where I don't find the pins RX/TX.

    Any of the I/O pins P0 through P15 could be used as TX and RX pins. The pins used to control servos would also probably work P16 the P19 but I think the servo pins use series resistors which can interfere with some serial communication tasks (there was a recent thread about someone having trouble using the servo pins when interfacing with an XBee using a Propeller Activity Board).
  • PridborPridbor Posts: 30
    edited 2014-01-04 21:31
    I didn't think of that! Excellent idea.

    I have just found the object which Beau had attached, and I not noticed, and
    that is very helpful!

    Thank you all for your help, I might be back when I have the Displays in hand :-)

    Preben
  • PridborPridbor Posts: 30
    edited 2014-01-22 22:11
    Getting to the point where I shall connect the 4D display and the Propeller together.

    Now you gents have already answered the question on which pins to use for Rx, Tx, and Res, namely any, but the display program defines some pins which I shall then use.

    The question is: Can I safely power the display via the Propeller module? +5V. I assume that the USB and the module have limits as to how much current they can provide?

    or do I need an external supply which I then need to have a common ground between the two modules?

    Asking to be safe rather than sorry :-)

    Preben
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