CMPS12 + OLED display help - beginner

Projects General Guidance
1

I'm very new to this so apologies if I'm doing something stupid.

I've setup a cmps14 compass with an OLED display and have merged two codes I found together. It kind of works... except...

I have a strange fault down the left side of the display.
The display updates and the numbers change for the first 5-10 seconds and then it freezes.

any idea what I'm doing wrong?

I tried making my circuit in Fritzing, but the CMPS14 is not available as a component (Frustrating!)

cmps circuit
cmps circuit1280×960 311 KB 

/*****************************************
*   CMPS12 Serial example for Arduino    *
*        By James Henderson, 2014        * 
*****************************************/

#include <SoftwareSerial.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SH1106.h>

#define CMPS_GET_ANGLE8 0x12
#define CMPS_GET_ANGLE16 0x13
#define CMPS_GET_PITCH 0x14
#define CMPS_GET_ROLL 0x15
#define OLED_RESET -1
Adafruit_SH1106 display(OLED_RESET);

SoftwareSerial CMPS12 = SoftwareSerial(2,3);

unsigned char high_byte, low_byte, angle8;
char pitch, roll;
unsigned int angle16;

void setup()
{
  Serial.begin(9600);              // Start serial ports
  CMPS12.begin(9600);  
  display.begin(SH1106_SWITCHCAPVCC, 0x3C);
  display.clearDisplay();
}

void loop()
{

    CMPS12.write(CMPS_GET_ANGLE16);  // Request and read 16 bit angle
  while(CMPS12.available() < 2);
  high_byte = CMPS12.read();
  low_byte = CMPS12.read();
  angle16 = high_byte;                // Calculate 16 bit angle
  angle16 <<= 8;
  angle16 += low_byte;
  
  CMPS12.write(CMPS_GET_ANGLE8);  // Request and read 8 bit angle
  while(CMPS12.available() < 1);
  angle8 = CMPS12.read();
  
  CMPS12.write(CMPS_GET_PITCH);   // Request and read pitch value
  while(CMPS12.available() < 1);
  pitch = CMPS12.read();
  
  CMPS12.write(CMPS_GET_ROLL);    // Request and read roll value
  while(CMPS12.available() < 1);
  roll = CMPS12.read();

     display.clearDisplay();
display.setTextSize(0);
display.setTextColor(WHITE);
display.setCursor(0,10);
  display.print("roll: ");            // Display roll data
  display.print(roll, DEC);
  
  display.setCursor(0,20);
  
  display.print("pitch: ");          // Display pitch data
  display.print(pitch, DEC);
  
  
  display.setCursor(0,30);
  display.print("angle full: ");       // Display 16 bit angle with decimal place
  display.print(angle16 / 10, DEC);
  display.print(".");
  display.print(angle16 % 10, DEC);
  display.display();
  

  display.setCursor(0,40);
  display.print("angle 8: ");        // Display 8bit angle
  display.print(angle8, DEC);
   display.display();
  display.clearDisplay();
  delay(500);                           // Short delay before next loop
}

Thanks
Alastair

2

Does not make a whole lot of sense.

Have you tried some troubleshooting?

display.clearDisplay();
display.setTextSize(0);
display.setTextColor(WHITE);
display.setCursor(0,10);
  display.print("roll: ");            // Display roll data
  display.print(roll, DEC);
  
  //display.setCursor(0,20);
  
  //display.print("pitch: ");          // Display pitch data
  //display.print(pitch, DEC);
  
  
  //display.setCursor(0,30);
  //display.print("angle full: ");       // Display 16 bit angle with decimal place
  //display.print(angle16 / 10, DEC);
  //display.print(".");
  //display.print(angle16 % 10, DEC);
  //display.display();
  

  //display.setCursor(0,40);
  //display.print("angle 8: ");        // Display 8bit angle
  //display.print(angle8, DEC);
   //display.display();
  delay(500);                           // Short delay before next loop
}

Does the above code change give you an error?

and how many of these display.display(); are needed to update the display? Just one?

3

Well done posting code this way, using code tags!
Code that hangs after 10 seconds.... I ask You to post an engineering wiring diagram, pen and pencil, but not any painting named Fritzing
I want to check for power overload somewhere.

4

Thanks for you help! i tried your code but it displays 0's as compass readings. Now I'm very confused!

5

hi railroader,
here's a wiring diagram
cmps + oled.pdf (347.8 KB)

6

Did the display mess up, is the question I want to know if not then uncomment a few more lines. did it mess up, then uncomment a few more lines, till you find the spot where the code messes up the display.

7

Ah i see what you’re trying to do! Will try again tomorrow as its getting late here in Belgium!

8

so this gave me a crazy screen, but I then uncommented the last display.display(); and it worked with showing only the roll data.

yes, only one display.display(); is needed in total.

I think the issue with the updates freezing might be related to a memory issue. I get a message after uploading...

"Global variables use 1695 bytes (82%) of dynamic memory, leaving 353 bytes for local variables. Maximum is 2048 bytes.
Low memory available, stability problems may occur."

9

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