Hey guys,
I am currently working with the "SparkFun Load Cell Amplifier - HX711" (product page).
When I used it with 10 SPS everything worked grear. However, I modified the board to achieve 80 SPS according to this entry by a Sparkfun Employee on this site
On the back, there is two little solder pads in brackets, with “rate” written under it, to “open the jumper” take a scalpel and just separate the connection which is part of the printed board.
The board now spits out 80 SPS but there are extrem spikes every now and again. The interval between them starts at about 5 seconds and decreases over time.
screen shot
Have you got any idea what to do about this? I am very grateful for any help!
You might watch for "fliers" (readings that are out of reason) and just ignoring them.
// pseudo code
if(reading > low bound && reading < hibound)
upddate reading;
Can you post your code? HowToPostCode
edgemoron:
You might watch for "fliers" (readings that are out of reason) and just ignoring them.
// pseudo code
if(reading > low bound && reading < hibound)
upddate reading;
Well this would be a quick and easy fix but it gets increasingly worse to the point where half of my data consists of "fliers".
Here are Screenshots from different times.
Also I want a high update rate because I want to generate a trust curve of an engine of a modell rocket.
The time between spikes does NOT "reset" when I reset the Arduino but it goes down again when I unplug the Arduino for a couple of seconds.
My code is just the example code from the library only modified a bit:
#include "HX711.h"
HX711 scale;
void setup()
{
Serial.begin(38400);
Serial.println("HX711 Demo");
Serial.println("Initializing the scale");
// parameter "gain" is ommited; the default value 128 is used by the library
// HX711.DOUT - pin #A1
// HX711.PD_SCK - pin #A0
scale.begin(A1, A0);
scale.set_scale(2280.f); // this value is obtained by calibrating the scale with known weights; see the README for details
scale.tare(); // reset the scale to 0
}
void loop()
{
Serial.println(scale.get_units(), 1);
}
Any ideas? 
Try disconnecting your load cell from the HX711 and feed half of the excitation voltage to both A+ and A-. Then look at the raw counts: should be stable at about half of the maximum count. If it is stable, then your load cell and its wiring may have...problems.... Loose wires? EMI?
PS: is the code you posted your code? Judging from the scale factor (2280), it probably isn't your code. Post YOUR code. And nice clear photos of your wiring may be helpful.