Log Weight Changes to EEPROM

[alexanderkjones]

Story
As a User, I want to measure pour data from a keg and store locally on the device, in order to capture data for batch analysis.

Desc
The device when monitoring a Keg is looking for changes in weight to signify a pour start and stop to calculate the pour size and timestamp. We've implemented a method for monitoring the keg for pours below. We want to store all readings locally ATC EEPROM not ESP EEPROM for batch export. Export will be a separate Story/Issue

Method
To measure keg pours we watch for stable weight readings in 5 second intervals. Every 5 seconds the weight is checked, if the weight is the same as the last reading the reading is considered stable. If the reading is different we know there is a pour occurring which may take more than one 5 second interval to complete so we begin a new comparison for a second stable reading. I've organized this using two setpoints in an array setpoint[0,1]. Once we have a second stable reading, we mesure the delta between the two points, reset setpointp[0] with the latest stable weight, and store the delta with timestamp as a pour to be transmitted to the system.

Acceptance Criteria

• The device follows the method to store a pour data point ie delta/timestamp
• The developer can execute a Serial.println() of the stored datapoints in EEPROM.

Code Example

int scaleSampleWeight(){
  scale.power_up();
  int sample = scale.get_units(25);
  //Throw away last bit
  sample = (sample/10)*10;
  scale.power_down();
  return sample;
}

void watch_keg(){
  int thisRead = scaleSampleWeight();

  Serial.println(thisRead);

  if(thisRead != setpoint[0]){

    if(thisRead == setpoint[1]){
      int delta = setpoint[1] - setpoint[0];

      if(abs(delta) > 10){
        trackpour(delta);
      }

      setpoint[0] = setpoint[1];

    }else{
      setpoint[1] = thisRead;
    }
  }

} 

[alexanderkjones]

@JLJTGR when's you're next availability for this issue?

[JLJTGR]

I'm still trying to figure out the usage of the HX711 library. So far the only values I get out of it are 2147483647 and -2147483648 (0b01111111 11111111 11111111 11111111 and 0b10000000 00000000 00000000 00000000)

[alexanderkjones]

@JLJTGR Here's working code for initializing HX711. I think you may have pins incorrect.

#include "HX711.h"

/* Initialize Scale*/
HX711 scale(12, 13);

void setup() {

  Serial.begin(115200);
  delay(100);

  scale.set_scale(43.5);
  //scale.tare();

}

[JLJTGR]

I don't think that's quite it at all. Maybe the current library is fairly different than the one you were used to using. 14/12 are definitely the correct pins. Your previous sample code assumes an int where the function returns a float. You then decimate that truncated float by a power of ten, which causes any reading below 10 lbs to become zero. Your scale calibration value is vastly different than my working one.

In short, I didn't understand what your code did, so when I used it blindly it didn't work and I didn't know how to fix it. So I just did that portion from the ground up so I actually had an understanding of it.

[JLJTGR]

Output example...

Sleeping for 5 seconds...
2016-05-04 | 18:21:56
TrackPour: -12
Sleeping for 5 seconds...
2016-05-04 | 18:22:06
Sleeping for 5 seconds...
2016-05-04 | 18:22:16
Starting local AP: ESP_01560E...
Local AP IP: 192.168.4.1
Web server started...
Connecting to SSID: JLJTGR...
Connected; WAN IP: 192.168.173.100
Exporting 4 packets....
2016-05-04 18:19:57 = -14
2016-05-04 18:20:47 = -11
2016-05-04 18:21:17 = -11
2016-05-04 18:21:58 = -12
Done.
Disconnecting...

[JLJTGR]

I should mention that this code requires Arduino 1.6.8 to compile properly by the default IDE. There is a bug that causes the ESP8266 libraries to crash the prototyping function of the default Arduino Builder and the compile will fail.
arduino/arduino-builder#68