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  • mborgerson's Avatar
    08-11-2020, 08:37 PM
    I'm glad you got something working. Your "Collect during yield" approach should work OK, since the SD routines will keep checking for data during the longer SD card write intervals. Note: If you are using SDFat...
    12 replies | 270 view(s)
  • mborgerson's Avatar
    08-10-2020, 04:23 PM
    I can understand that. Serial.flush() starts a series of USB transactions to send the data. How fast that can be done probably depends on how busy the computer on the other end of the USB cable happens to be at the...
    24 replies | 789 view(s)
  • mborgerson's Avatar
    08-10-2020, 02:22 AM
    To make that kind of decision you need to specify very carefully what you mean by 'accuracy'. If your sensor has significant output impedance, or you add an RC filter at the ADC input, if you sample too quickly your...
    24 replies | 789 view(s)
  • mborgerson's Avatar
    08-10-2020, 01:05 AM
    I modified my sample code to use interleaved ADC collection per jonr's sample code and added some timing data collection using the ARM cycle counter. I also tested with the resolution set to 12 bits. With the new...
    24 replies | 789 view(s)
  • mborgerson's Avatar
    08-09-2020, 04:01 PM
    Note that the sample code writes the ADC data in binary format as a series of bytes. Part of the process of uploading the binary data would be to convert the series of binary bytes to human-readable format. Simply...
    24 replies | 789 view(s)
  • mborgerson's Avatar
    08-06-2020, 12:24 AM
    Just out of curiosity I dug out a PCB with a Linear Technology LTDC1867L and wired it up to a T4.1. I collected data at 1000 samples per second to check noise levels. Test Setup: T4.1 connected to LT1867 reading...
    35 replies | 651 view(s)
  • mborgerson's Avatar
    08-05-2020, 04:22 PM
    It gets even worse when you try to write the data to an SD Card. Parts of the write cycle can involve short current spikes of 100mA or more. That puts a lot of stress on the Teensy's 3.3V regulator. The SD card...
    35 replies | 651 view(s)
  • mborgerson's Avatar
    08-05-2020, 04:09 PM
    I ran the posted example code overnight and it collected good data for about 16 hours. Once you get the GPS collection and file open/close stuff under control, you can start to work on the really interesting part: ...
    12 replies | 270 view(s)
  • mborgerson's Avatar
    08-04-2020, 11:58 PM
    The generic logger code and examples were posted in the "Project Guidance: forum a month or two ago. You can search for "generic data logger:. Here is a mod of your code that I've simplified a bit and added a...
    12 replies | 270 view(s)
  • mborgerson's Avatar
    08-04-2020, 06:29 PM
    You do not need to open and close your file each time you write to it. Your code should look more like this: file myFile; void setup(){ // generate initial file name, start timers, etc. myFile =...
    12 replies | 270 view(s)
  • mborgerson's Avatar
    06-27-2020, 05:16 PM
    I haven't worked with external card readers on the T4.0. I got out my binocular microscope, finest tweezers and soldering tip and coerced a micro-sd card socket to bond with the misfit pads on the bottom of the T4.0. ...
    86 replies | 2400 view(s)
  • mborgerson's Avatar
    06-27-2020, 02:31 AM
    Here is a link to the MTP library I am using. I haven't posted it before because you have to edit some of the core USB libraries to get it to work. If you've gone through that before, you should be able to get a USB...
    86 replies | 2400 view(s)
  • mborgerson's Avatar
    06-26-2020, 09:58 PM
    I've attached a zip file with the latest incarnation of the generic data logger. It has been updated to allow the use of more than one logger object in a program. I have added an example that uses a slow and a...
    86 replies | 2400 view(s)
  • mborgerson's Avatar
    06-25-2020, 05:07 PM
    With some simple mods to the generic logger, I am now able to use two logger objects to save data to two different files at different collection rates. Apparently, SDFat 2.0B has no problems having two files open for...
    86 replies | 2400 view(s)
  • mborgerson's Avatar
    06-24-2020, 08:00 PM
    Your comment that some applications really don't fit the timer-based buffering and storage model is spot on. The GPS logger is really a bit of a stretch. It might be be better done by increasing the size of the...
    86 replies | 2400 view(s)
  • mborgerson's Avatar
    06-24-2020, 03:13 PM
    I've considered the possibility of event-triggered logging, and I think it could be implemented with a modification of the solar logger example. For event-triggered logging, the attached binary writer would examine the...
    86 replies | 2400 view(s)
  • mborgerson's Avatar
    06-24-2020, 03:02 AM
    Sorry about the delay in response to questions---but I was on a camping trip where I tested a version of the data logger software to collect GPS data. GPS collection is a bit of a PITA in that you get a swarm of NMEA...
    86 replies | 2400 view(s)
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About mborgerson

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About mborgerson
Biography:
building embedded systems for oceanographers since 1978
Location:
Corvallis, OR
Interests:
travel
Occupation:
Retired embedded systems engineer

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teensy 3.5 freezes when data logging 08-11-2020 08:37 PM
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02-01-2018