Openlog artemis firmware 1.6 out of box works great (IMU and date-time stamps ) whether LiPo powered or direct USB connected and whether on SD card or on monitor.
When connected to Qwiic Scale (no other I2C devices and via Qwiic only) i get new column of data as expected but all values are “nan” as in “not a number” I presume
I used my Artemis Redboard with Qwiic and load the Arduino library for the Qwiic Scale and I first see negative numbers , so I switch green and white leads from load cell and now get positive numbers that vary appropriately with force applied to load cell. I figure maybe the OL Artemis doesn’t know what to do with negative numbers from Qwiic Scale so with much hope, I reconnect to OLA and still see only “nan”.
The OLA gathers data at 10 Hz so I do not think this is too fast to get data (?) from the Qwiic Scale - although ultimately I want to gather at 320Hz. I want the date-time stamp for logging (good old RTC on the OLA) and would rather not have to code the Artemis Redboard to print date-time with each force measurement, but if I have to … well ?
I want to record times of load and no load events for students to observe distance and time in falling and bouncing in gravity (to start!)
Cannot calibrate via OLA - only see “inf” (no load) and “nan” (with load) reported .
Would a cailibration done with the Artemis Red Board Qwiic remain in effect when I hook up with the OLA? This sounds likely since the NAU should be holding the calibration information , right?
Are you sure you have your scale connected correctly?
The NAU7802 works OK for me. Here is what I see using a “kitchen scale” to weight a 100g weight. The first attachment shows the data in the serial monitor. The second shows the data in the serial plotter. The third shows the calibration process.
all connections from either the OLA or Artemis Redboard to the NAU are with qwiic
I was not able to use the NAU with the OLA (via qwiic) at the beginning , so I brought out my Artemis Redboard qwiic and as noted in my initial message , it was able to log raw values from my 5kg load cell but always negative and, with added weight, the values became more negative. When I switched the white and green wires from the load cell to the NAU , the raw values reported were now positive and increasingly positive with added weight.
No I did not calibrate the NAU while hooked to the Artemis Redboard qwiic, since I do not need calibrated weight. I just need to know if the load cell is at “rest” or “loaded” . Also since I do not get any numerical values when using the OLA with the NAU, I cannot calibrate it. Reviewing your attachments, it is clear that you must have
I can do a Artemis Redboard qwiic calibration once I get a mount for the reference weight .
You can - and must - calibrate the NAU before the OLA will give you any sensible readings. It does not need to be an accurate, absolute calibration. Just a very simple approximate calibration to remove the sensor offset.
Please open the serial menu, select the “Configure Attached Devices” menu, select your NAU7802 from the list, select option 2 to calibrate.
With no load on the load cell, press enter.
Then put a small load on the load cell - it does not matter how much - and press enter.
Now enter a value. It does not matter what value you use. I suggest “100”.
Exit the menu.
The NAU will now be ‘calibrated’ and you should now see values instead of “nan”?
