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31  Using Arduino / Project Guidance / Re: 6 digit 7 Segment display - TPIC6B595 schematic component? on: March 13, 2013, 10:11:12 am
Ok, seems simple enough.  I'll have to dig through the datasheet on the LCD screen and see how I need to modify my code to send it text using SPI.

As for the PPS signal, I haven't played around with providing any input to the Arduino.  I guess I need to look into the pulseIn information?
32  Using Arduino / Project Guidance / Re: 6 digit 7 Segment display - TPIC6B595 schematic component? on: March 13, 2013, 08:30:20 am
I changed the baud rate for the LCD screen and it didn't change how the 2 displays were out of sync.  So, I'm thinking that it is either: code related, using serial with the display is slow, or the display is just slow regardless.  I'll try using SPI with it. (I just need to solder on a few more pins to my lcd)

Now, if I want to use SPI with the LCD screen, do I just daisy chain the MOSI & SCK lines from my 7 segment displays along with adding another line from my Arduino as a second Latch?

Some other questions...
1. I've noticed that my LCD screen flickers.  It seems to be in time with when it updates every second.  Could this is something to do with the power?  Speaking as a non-electronics guy, if it is power related (and not simply a cheap screen with inherent defects) would adding a capacitor help?  If so, how do I add it into my circuit? (polarized electrolytic across + to - at the display?)

2. Looking at 7 segment LED display, the time sometimes skips over a second or laggs. Like it will display 11:40:01 then 11:40:03.  I'm using the example code from the Adafruit website to grab the GPS time.  Like this:
Code:
// if a sentence is received, we can check the checksum, parse it...
if (GPS.newNMEAreceived()) {
    GPS.parse(GPS.lastNMEA());   // this also sets the newNMEAreceived() flag to false
   
    // Update our clock variables with the GPS time
    clocksecond = GPS.seconds;
    clockminute = GPS.minute;
    clockhour = GPS.hour;
}

I then use my clock variables to set the numbers on the display.  Could it be that the GPS isn't always sending out an update every 1 second?  The GPS is using a SoftwareSerial connection to the Arduino. Could that be part of the reason?  Or, could it be taking the Arduino longer to parse the serial data at one time and less at another time?

Or, should I be going about getting the time from the GPS in a different way?  I was searching around and came upon this post:
http://forums.parallax.com/showthread.php/116008-How-accurate-can-a-data-quot-time-stamp-quot-be-made-for-a-GPS-with-the-Propeller?p=840749&viewfull=1#post840749

Quote
Yeah, typically the serial data starts transmission on the PPS, but at 9600bps, it can be a long time before you actually get your data out of it (and it's not really convenient to watch for an edge on serial data like it is to watch for a PPS line). I typically watch for the PPS, then I know what time that PPS was by reading the GPS data that follows it.

There is a PPS pin on the GPS unit.  Anyone have experience with using this?  I might try posting my question over on the Adafruit forum...
33  Using Arduino / Project Guidance / Re: 6 digit 7 Segment display - TPIC6B595 schematic component? on: March 12, 2013, 08:14:29 am
From the LCD datasheet, it looks like I can change the BAUD rate with a command.  The default is 9600.  The display can go all the way to 115.2K.  I'll try changing it tonight and see if I get better results.

Also, the LCD display can be controlled by either Serial, I2C, or SPI.  Is one better over the other?
34  Using Arduino / Project Guidance / Re: 6 digit 7 Segment display - TPIC6B595 schematic component? on: March 11, 2013, 10:47:53 pm
Ok, I think I understand.  As for the battery, I'll probably go 15V w/switching regulator.

Some more updates.  I have my breadboard now hooked up to my GPS and it is pulling in the GPS time and displaying it on the 6 digit displays.  I also have a 4 line 20 character LCD screen.  It is hooked up to the Arduino via a Software Serial connection.  I have both the 6 digit LED displays and the 4 line LCD displaying the time from GPS. 


Now, my problem.  The LCD lags behind the 6 digits.  It is around a half second delay.
Is this because there is a long delay with using Serial?  Or could it be the cheap screen I'm using?
35  Using Arduino / Project Guidance / Re: 6 digit 7 Segment display - TPIC6B595 schematic component? on: March 11, 2013, 01:04:52 pm
Ok, so I'm starting to get together a list of components for my full size prototype, and I'm thinking about power requirements.

Can anyone help me or point me in the right direction with batteries?

For instance, I'm looking at 2 LiPo batteries.  One is 5500mAh at 7.5V and the other is 5500mAh at 15.0V.  I plan on using a DC-DC switching regulator to step down the battery voltage to 5V for the Arduino (like this: http://www.digikey.com/product-detail/en/OKI-78SR-5%2F1.5-W36-C/811-2196-5-ND/2259781?cur=USD) and use the voltage straight from the battery to power the LED displays.  (good / bad idea?)

For the sake of simplicity, lets say each of my display segments uses 6 LEDs and each LED is 2.5V.  So, for my 7.5V battery I could wire 2 rows of 3 LEDs in series and for my 15V battery I could wire 6 LEDs in series (correct?)

Now with my battery, will my displays last just as long, since each battery is 5500mAh?
36  Using Arduino / Project Guidance / Re: 6 digit 7 Segment display - TPIC6B595 schematic component? on: March 11, 2013, 07:40:05 am
The way its coded, it will display 654321.

Its up you to define what goes where, there isn' a standard.
Ok, that's what I thought.

You have no current limit resistors? That will burn out your LEDs eventually. The TPIC6B595 can sink a lot of current.
I have 1 small resistor on each of the common anodes of the 7 segment displays.  I sized it so if I was displaying the number 1, it would be about 10mA.  If I show an 8, the display dims more.  I would add resistors to each individual led for my final project, but I didn't want to put in 42 resistors on my breadboard for this. (plus I didn't have that many on hand)
37  Using Arduino / Project Guidance / Re: 6 digit 7 Segment display - TPIC6B595 schematic component? on: March 10, 2013, 09:50:23 pm
Yes, they are daisy chained.

Is there a standard way they should be hooked up? Like, should the first display be on the far left or far right?
Here is what I show with my display and how it's hooked up.


Serial In goes to #1, then Serial out of 1 goes to in of #2, etc...

Using your suggestions, here is my test code. Works so far.
Code:
// Test sketch using 6 TPIC6B595 shift registers
#include <SPI.h>

const static byte charTable[128] = {
  // B-DP-g-f-e-d-c-b-a
  //    a
  //f       b
  //    g
  //e       c
  //    d       DP
 
  //0         1         2         3         4         5         6         7
    B00111111,B00000110,B01011011,B01001111,B01100110,B01101101,B01111101,B00000111,
  //8         9
    B01111111,B01100111
};

const byte LATCH = 10;     //Arduino Latch Pin = 10
const byte NumberOfSR = 6; //Number of Shift Registers

byte DisplayData [NumberOfSR]; //Array for numbers that go in the 6 digit display

void refreshDisplay ()
{
  digitalWrite (LATCH, LOW);
  for (byte i = 0; i < NumberOfSR; i++)
    SPI.transfer (DisplayData [i]);
  digitalWrite (LATCH, HIGH);
}

void clockDisplay ()
{
  DisplayData [0] = charTable[1];
  DisplayData [1] = charTable[2];
  DisplayData [2] = charTable[3];
  DisplayData [3] = charTable[4];
  DisplayData [4] = charTable[5];
  DisplayData [5] = charTable[6];
  refreshDisplay ();
}

void setup ()
{
  SPI.begin ();
}
 
void loop ()
{
    clockDisplay ();
}

I'll most likely use the decimal points for my lights and just use 2 more TPIC6B595's for the other 2 larger digits.  Or, I may even use another 595 for the lights. That way I can daisy chain everything with some headers & cables.
38  Using Arduino / Project Guidance / Re: 6 digit 7 Segment display - TPIC6B595 schematic component? on: March 10, 2013, 05:36:10 pm
Some updates:

I have my TPIC6B595 registers wired up to some small 7 segment displays.  I have tested them with a sketch that I downloaded from Nick Gammon's site http://www.gammon.com.au/forum/?id=11518&reply=1#reply1  and all of the segments light up, so I know everything is wired up correctly and working. Hard to see, but I have a capacitor across the + and - for a decoupling capacitor.  I also just used 1 resistor per display, since I didn't have 42 resistors for each led segment, so it does dim as more segments light up.



Now, my question.  Are there some code samples/examples on how to display numbers onto my 6 digit display?  Previously when I was using the Embedded Lab SPI 7-seg display http://embedded-lab.com/blog/?p=6862  the code was very simple.  Like:

Code:
#include <LedControl.h> //  need the library
LedControl lc=LedControl(4,3,5,1); // lc is our object Pin 4, 3, 5  and 1 display

clockminute = minute();
clockhour = hour();
lc.setDigit(0,6,clockhour,false);
lc.setDigit(0,3,clockminute,false);

Where I used lc.setDigit to send the display what number I wanted for my hour, minute, second.

Is there a similar Library for using 595 shift registers?  Also, should I be using SPI.h or ShiftOut() to update my display? (I've started reading a bit about each)
39  Using Arduino / Project Guidance / Re: 6 digit 7 Segment display - TPIC6B595 schematic component? on: March 07, 2013, 09:55:14 pm
I think I calculated too high (made a newbie mistake) and assumed they are all on at the same time.  Should be more like 3.9A at 20mA per LED.

Anyone have a suggestion for controlling the brightness using the TPIC6B595? 
40  Using Arduino / Project Guidance / Re: 6 digit 7 Segment display - TPIC6B595 schematic component? on: March 07, 2013, 02:33:16 pm
I'm starting to consider the power requirements of my project... and to have a bright display for outdoor use, it seems like I'll need a big battery.

So, using the TPIC6B595, is there a way to control the brightness of the LEDs, in order to reduce my power requirements when it isn't full sun (cloudy days, night, indoors)?

If I make my own digits out of LEDs; assuming 28 LEDs for 6 small segment, 77 LEDs for 2 large segments, 10 LEDs for 3 round lights;  I get 352 LEDs  (I might reconsider how many I use for the large ones).  If I run them at 20mA, I'll have about 7000mA for the display.  Seems like a lot of power, since I was considering batteries that have a capacity of 7Ah.  Would only run my display for 1 hour, right?

So... if there is an easy way I could have a dial or menu system control the brightness, I would prolong the display time.
41  Using Arduino / Project Guidance / Re: 6 digit 7 Segment display - TPIC6B595 schematic component? on: March 06, 2013, 05:28:53 pm
Ok, here is my project idea... just an overview of what I'm planning.  Anybody, feel free to make suggestions on components.

42  Using Arduino / Project Guidance / Re: 6 digit 7 Segment display - TPIC6B595 schematic component? on: March 06, 2013, 02:57:35 pm
Wow, looks cool.  Making my own LED segments might be an option I'll consider.  I just initially figured it would be easier to buy the segments so I would have less assembly work.

As for your LED driver board (using TPIC6B595), is this what you mean ?


In the mean time, I'll try and sketch something out on paper and post it here.
43  Using Arduino / Project Guidance / Re: 6 digit 7 Segment display - TPIC6B595 schematic component? on: March 06, 2013, 12:15:47 pm
Thanks for the links.

Do you have any suggestions on the mCD output needed for a display to be visible outdoors?

I'm not opposed to making my own LED digits, kind of like this http://www.ebay.com/itm/LARGE-5-127mm-TALL-BI-COLOR-LED-7-SEGMENT-DISPLAY-100-USA-BUILT-/321036681257?pt=LH_DefaultDomain_0&hash=item4abf470029

Only reservations would be soldering up all of those LEDs onto boards for 6 digits.  Plus, I'd have to make a custom board (unless you know of boards available for purchase)
44  Using Arduino / Project Guidance / Re: 6 digit 7 Segment display - TPIC6B595 schematic component? on: March 06, 2013, 11:23:28 am
I haven't really decided on a specific 7 segment display yet, but most of the larger displays I see are 7-12 volt.  I'm not really set on a certain type or size just yet.

So far I've seen displays like this one:
http://www.ebay.com/itm/4-inch-7-segment-RED-LED-display-common-anode-1pcs-/360608554918?pt=LH_DefaultDomain_0&hash=item53f5f1dfa6
Voltage:10V~12V  Current:160mA

But maybe eBay isn't the best choice?  I don't see many specs on that display (like brightness).  I want a bright display for outdoor viewing in the sun.

I've seen some other displays on Digikey
http://www.digikey.com/product-detail/en/LDS-AD16RI/67-1493-ND/253656
6.8V  10mA

or

Mouser
http://www.mouser.com/ProductDetail/Lumex/LDS-AD14RI/?qs=sGAEpiMZZMvkC18yXH9iIodCS3EcCJg%2fvIF5cWbQeXU%3d
8V 30mA

I've also seen some that are only 1.85V 30mA (although not in stock)
http://www.mouser.com/ProductDetail/Kingbright/SA23-11SRWA/?qs=sGAEpiMZZMvkC18yXH9iIgvC7dgeX7B5331BdgRjLvY%3d

So far, I've been working on a small prototype on my breadboard.  Once I get the software to work how I want it, then I'll start making a full size version.  I've been trying to read a lot and see what others have done before, but lots of projects look to be unique.  Just trying to figure out all of the different options out there for what will work best for me. Daunting task for a non-electronics guy.

I'll PM you later for the component for expressPCB software.  Thanks!
(I'm still amazed at how easy it is to program something on the Arduino and have it do things. Never thought it would be this easy.)
45  Using Arduino / Project Guidance / 6 digit 7 Segment display - TPIC6B595 schematic component? on: March 06, 2013, 09:50:07 am
Hi all.  First off, an introduction.  I'm John Huebbe... new to electronics but experienced with programming.  Just picked up an Arduino and some components a week ago.  So far, so good with simple projects (LEDs, speaker, push buttons, small 7 segment display).

I'm building a large (2 to 5 inch high numbers) 6 digit 7 segment display.  Some background info... I already have my code working while using the embedded-lab SPI7SEGDISP8.56 MAX7219 based serial 8-digit seven segment LED display module  http://embedded-lab.com/blog/?p=6943  (took me longer to solder up than program)

From reading a ton of forum posts (most where CrossRoads has replied) it looks like it would be best not to use the MAX7219 to drive larger displays and I think it best to use the TPIC6B595 to drive them.  Right? 

So, I'm trying to come up with a basic schematic using the ExpressSCH software, but I don't see a TPIC6B595 component.  I already tried searching but couldn't find a component to download.  Does anyone already have this made?  Or, have I missed seeing it in the software?

Also, does anyone already have a schematic drawn up using these?
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