Arduino GPS Speedo

[Ribenapigeon]

Anyone here a dab hand with Arduino?

Ive started making a GPS Speedo HUD. Ive got the optics worked out basically using an old objective lens from a cheap pair of binoculars and some semi reflective film. Ive managed to get a GT-u7 GPS working hooked up to a Arduino UNO R3 and I've also got a small Oled i2C working with an example script. IM struggling to write a script to take the speed output from the GPS and then put that value to output to the Oled but I'm lost. The library I'm using for the GPS is TinyGPS++ and the Oled is SSD1306_128x32_i2C

I would prefer to output to seven segment display really as that would be clearer for projecting the number onto the HUD but i only have an Oled display.

Cheers.

BTW I've tried the Arduino forums but they're more anally retentive than Mumsnet

[WD Forte]

Interesting, how are you projecting it on a visor? any pics?

(Could it perhaps wash the visor and save lives while its at it?
Just asking)

Cant help with code I'm afraid as I'm very very rusty and only recently dug out
my Arduino stuff after such a long time that I'm having to do all the basic stuff
all over again just to refresh my brain.
I have some 7 seg common cathode led displays and they'd need a lot of pins, multiplexing or shift register circuits,so serial displays score there for me.
Having said that, I see Sparkfun offer a 41x23mm serial type 4x7 segment display which would cut down on pin/cable use.
https://www.sparkfun.com/products/11629

As for code, I usually shamelessly grab other peoples and butcher/feck about with it to get it to do what I want it to.

Edit
A quick google got me this based on a pro mini
but it may have some handy snippets you can borrow
to get it functional then deal with the method of display/HUD as a seperate project

https://create.arduino.cc/projecthub/fanatic-series/gps-speedometer-using-arduino-pro-micro-0a8fde
____________________
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[The Shaggy D.A.]

Some time back I found a post showing how to use PWM and a cheap digital voltmeter as a cheap display :-

https://picaxeforum.co.uk/threads/1-digital-voltmeter-becomes-one-pin-led-display.27594/
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[Ribenapigeon]

[Ribenapigeon]

[Easy-X]

Best to break these projects into stages. I dunno what sort of Arduino you have but it helps if you have one (most I think) that has serial console I/O. You then have a simple way of outputting data.

For example: Step 1 might be to just get a speed output from your GPS module. Spit out the results to the console. Start with getting raw data out, they do some calculations to get lat/long, and so on.

Step 2 might be to take input, e.g. a number and show it on your display. There should be some standardised libraries to magic up the console operations to save you some work.

Also, if you get frustrated with the GPS you can just switch over to the display side for a bit of a rest.
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[Ribenapigeon]

[Easy-X]

You'll probably be needing something like a font generator:

Text -> Font generator -> Bitmap -> Raw Hex Image -> OLED library

Something like that?
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[WD Forte]

I just ordered an I2C 128x64 oled screen to fiddle with
had a quick shufty at the code and text looks simple enough
along the lines of-

display.clearDisplay();
display.setTextSize(1);
display.setTextColor(WHITE);
display.setCursor(0, 0);
// Display static text
display.println("Hello world");
display.display();
I reckon you'd just need to extract and store the speed from the GPS data stream
as a variable, say 'gps_speed' for instance which will probably be in kms
then use summat like
display.println(gps_speed*0.62);
to get MPH

The quality and update speed of the gps model will affect how accurate it is
of course
Graphics are bitmaps and more memory or program space hungry and more code intensive
as well.

The link I posted above shows you how do it, you could easily mod that code.
Arduino gps looks pretty easy as there's a lot of off the shelf
resources to borrow from.
Its getting a good HUD without it looking all Heath Robinson of feckin up your night vison that will be the tricky part.
____________________
bikers smell of wee

[Easy-X]

Dunno if the display library handles automatic number to text conversion...

[Ribenapigeon]

[WD Forte]

Got one o them wee displays today and had feck about with it tonight
running it from a Nano.

Handheld Sat knavery
https://imgur.com/SVGBdwY.jpg

Hooked up an LM35 temp sensor and displaying a variable was easy enough, just like any other display.

https://imgur.com/3U2OAmV.jpg

will look into fonts,formatting and graphics in more detail later
____________________
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[Im-a-Ridah]

GPS messages come over UART, just loop commas until you get to the speed value.

[Ribenapigeon]

I need to get back on this.

[Ribenapigeon]

OK I have this script for the GPS Speed Data.

#include <SoftwareSerial.h>

SoftwareSerial ssPort(4, -1);

const byte numChars = 64;
char receivedChars[numChars]; // an array to store the received data
char rmcLine[64];
boolean newData = false;

char *strings[16];
char *ptr = NULL;
float knots2MPH = 1.1507794;
float speed = 0;
boolean speedIsValid = false;

void setup()
{
Serial.begin(115200);
ssPort.begin(9600);
Serial.println("<Arduino is ready>");
}

void loop()
{
recvWithEndMarker();
getRMCdata();
}

void recvWithEndMarker()
{
static byte ndx = 0;
char endMarker = '\n';
char rc;

while (ssPort.available() > 0 && newData == false)
{
rc = ssPort.read();

if (rc != endMarker)
{
receivedChars[ndx] = rc;
ndx++;
if (ndx >= numChars)
{
ndx = numChars - 1;
}
}
else
{
receivedChars[ndx] = '\0'; // terminate the string
ndx = 0;
newData = true;
}
}
}

void getRMCdata()
{
if (newData == true)
{
if (strstr(receivedChars, "$GPRMC") )
{
strcpy(rmcLine, receivedChars);
//Serial.print("This just in ... ");
//Serial.println(rmcLine);
byte index = 0;
ptr = strtok(rmcLine, ",");
while (ptr != NULL)
{
strings[index] = ptr;
index++;
ptr = strtok(NULL, ",");
}
if (*strings[2] == 'A') // if the fix is valid print speed
{
speed = atof(strings[7]) * knots2MPH;
speedIsValid = true;
Serial.print("Speed = ");
Serial.print(speed);
Serial.println(" MPH");
}
else
{
Serial.println("Speed not valid");
speedIsValid = false;
}
}
newData = false;
}
}


I have this for running the oled. It gets the error "serial does not name a type" when i try to compile. I don't understand this of course but i don't understand much of it anyway, I just cut out all the nonsense stuff in an example script for the old and left what i think is the bit i need to take the speed variable from the above GPS script (speed). How do i combine these two scripts? Im guessing W D Forte has basically done something simerler with his temp display?



#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 32 // OLED display height, in pixels

// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
#define OLED_RESET 4 // Reset pin # (or -1 if sharing Arduino reset pin)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);


Serial.begin(9600); //This gets the compiling error "serial does not name a type"

// SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally
if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // Address 0x3C for 128x32
Serial.println(F("SSD1306 allocation failed"));
for(;; // Don't proceed, loop forever
}


void testdrawchar(void) {
display.clearDisplay();

display.setTextSize(1); // Normal 1:1 pixel scale
display.setTextColor(SSD1306_WHITE); // Draw white text
display.setCursor(0, 0); // Start at top-left corner
display.cp437(true); // Use full 256 char 'Code Page 437' font

// Not all the characters will fit on the display. This is normal.
// Library will draw what it can and the rest will be clipped.
for(int16_t i=0; i<256; i++) {
if(i == '\n') display.write(' ');
else display.write(i);
}

display.display();
delay(2000);
}

void testdrawstyles(void) {
display.clearDisplay();

display.setTextSize(1); // Normal 1:1 pixel scale
display.setTextColor(SSD1306_WHITE); // Draw white text
display.setCursor(0,0); // Start at top-left corner
display.println(F("Hello, world!"));

display.setTextColor(SSD1306_BLACK, SSD1306_WHITE); // Draw 'inverse' text
display.println(3.141592);

display.setTextSize(2); // Draw 2X-scale text
display.setTextColor(SSD1306_WHITE);
display.print(F("0x")); display.println(0xDEADBEEF, HEX);

display.display();
delay(2000);
}


}
}
}
}

This is making my brain hurt. I could go the year long route of learning arduino form scratch but ya know......

[WD Forte]

It looks like you're trying to run the oled and serial monitor
at the same time?.
what if you comment out the spi.h - wire.h and 'serial begin' lines
and just use the Oled?

As I'm so rusty and never was an expert anyway K.I.S.S. helps.
I copy paste/butcher code to the absolute minimum to help myself
get my head around it all and this is what I used to get the oled running and display the temp sensor values
The idea is to start simple and get all elegant and fancy as I learn

Tip:
Select Arduino code and use Edit/'Copy for forum' to paste it here

[Easy-X]

On the second piece of code: sorry, never gonna work

You've missed off the setup() and/or loop() functions. Yer basic Arduino is looking for those in the same way a Windows Command Prompt program is looking for main()

void setup()
{
//Code here run on "boot up"
}

void loop()
{
//Code here run over and over
//Need to sleep at end if there aren't any blocking functions
}
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[Ribenapigeon]

[WD Forte]

mmm....... nearly

You put the #include libraries and global variable stuff before the

void setup() stage

There's where you do stuff like
Serial.begin(9600); to start the serial monitor
and
// SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally
(which lights the wick in the display engine dont it?)

Not sure what the rest means or where it goes
but basically its all run once stuff in setup().

Then you run the void loop() stuff in well.. a loop.

Any void stuff after that main loop is what I'd have called sub routines
many years ago, i think they may be called functions now?
dunno.
____________________
bikers smell of wee

[Ribenapigeon]

Thanks, I'll have another crack at it today. I used to be able to concentrate on this stuff when I was a pimpley teenager but these days I just can't.

[WD Forte]

Does yer bloody head in at times dont it?
I'm struggling to get my 128x64 oled to work properly
as I noticed it worked fine but only as a 128x32 with blank pixels in the vertical giving it a somewhat grainy look.
Going down a google rabbit hole in the wee hours I found its not just me
struggling, the feckin libraries are at fault so I'm not as thick as I thought
Apparently a library roll back sorts it, I hope.
I got the neo6 gps module running fine on a serial monitor, no problem there
When I get that fookin display to work properly, I'll see about combining them.
____________________
bikers smell of wee

[Ribenapigeon]

Ive used the AdafruitSSD1306 with no problems for both 128x64 and 128x32

[WD Forte]

Got it working in full res now
AdafruitSSD1306 my arse, its an SH1106
Similar, kinda works, but needs a different library.
That Ebay sellers' going to get a strongly worded letter in green ink!
____________________
bikers smell of wee

[WD Forte]

I must say that Neo6 gps module works pretty damn well.
I set it up on a breadboard on the window sill and ran a sketch
to output basic info (Lat/long/time/date/speed) to the serial monitor.
Putting the co-ordinates it gave on to google maps got it to within
an arms reach of where its actually located.
No speed info of course cos window sill
The Time to first fix ( TTFF) is damned fast as well,
I'd say within 10 seconds, a lot quicker than
my old 7" car satnav
IR Impressed.

next job, adding a display to make it portable
____________________
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[Ribenapigeon]

Im usnig a GT-u7 which i think is an update of the Neo6. Theres another one called a Grove but its three times the price and not worth it unless you know what your doing, which i clearly don't. Ive gone off to do something i understand better, digging the garden.