need help with serial monitor

Using Arduino Project Guidance
1

I am doing a project about optical sensor.

I was trying to read from an ADC, if I use the serial monitor, I can see the numbers jumping between -134 to -140. If I check the Serial Plotter ,I can only see a straight line on top of the window without any graduation on left side.

Can any one tell me how to fix it?

2

Hi,
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

Can you please post a copy of your sketch, using code tags?
They are made with the </> icon in the reply Menu.
See section 7 http://forum.arduino.cc/index.php/topic,148850.0.html

Thanks.. Tom.... :slight_smile:

3

Read the input, wait, read the input again, keep the second reading.
Add a 1uf cap across the input pin to GND.

4

Code is very simple,

#include <Wire.h>
#include <Adafruit_ADS1015.h>

Adafruit_ADS1015 ads1015;

void setup(void)
{
  Serial.begin(250000);
  //Serial.println("Hello!");
  //Serial.println("Getting differential reading from AIN0 (P) and AIN1 (N)");
  //Serial.println("ADC Range: +/- 6.144V (1 bit = 3mV)");
  ads1015.begin();
  ads1015.setGain(GAIN_ONE);
  //ads1015.setGain(GAIN_SIXTEEN);
}

void loop(void)
{
  int16_t results;
  results = ads1015.readADC_Differential_0_1();
  //Serial.print("Differential: "); Serial.print(results); Serial.print("("); Serial.print(results * 3); Serial.println("mV)");
  Serial.print(results);
  Serial.println();

}

just simply read from a ADS1015 ADC. I basically used the sample code from their company.

I found that if the output contains negative value only, there will be this problem ; Positive value only, no problem ; negative and positive value mixed, the graduation will be adjusted by the positive values only.
Is this a bug or something?

Another problem is , when the data values changes greatly, the plotter will back to work again, and when the data start to switch between two negative stable values, everythins will gone.

5

Hi.
Have you checked what readings you get with zero differential?

Tom... :slight_smile:

6

TomGeorge:
Hi.
Have you checked what readings you get with zero differential?

Tom... :slight_smile:

you mean the differential_0_1 reading? jumping between -134 and -140