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  • mborgerson's Avatar
    02-12-2020, 05:49 PM
    A friend asked me to look over the Analog Devices LTC6240 for a piezo-base oceanographic shear sensor. That op amp looks very good for piezo sensors because of the very low input bias currents--in the 1picoAmp range. ...
    31 replies | 2264 view(s)
  • mborgerson's Avatar
    02-11-2020, 07:54 PM
    Minimizing noise pickup from SD card writes is an ongoing project for me. I have found two main sources of noise: 1. The effect of the current peaks on the power supply. As you suggest, lots of capacitance can...
    7 replies | 116 view(s)
  • mborgerson's Avatar
    02-11-2020, 07:41 PM
    I've dug out a bit more information on the effect of sync() on SD Card power. I added a member function to the SDioCard object to return the number of times that transferStop() has been called since the start of the...
    7 replies | 116 view(s)
  • mborgerson's Avatar
    02-11-2020, 05:06 PM
    In order to more clearly illustrate the effect of the sync() call, I modified the data collection sketch to call sync() on odd-numbered writes of the 32KB ping-pong buffers. The result is shown in the following plot:...
    7 replies | 116 view(s)
  • mborgerson's Avatar
    02-11-2020, 04:42 PM
    The current measured in the test data was not measured with a meter. It was measured with a current sensor collecting data at 10KHz. The only integration in the Max471 sensor comes from a 0.1uF capacitor across the...
    7 replies | 116 view(s)
  • mborgerson's Avatar
    02-11-2020, 06:42 AM
    While working on a project to build a low-power data logger using a Teensy3.6, I discovered something a bit counter-intuitive. I found that calling the sync() function after writing a block of data to the output file...
    2 replies | 83 view(s)
  • mborgerson's Avatar
    02-11-2020, 12:08 AM
    I'm working on a low-power logger that runs at 8MHz and draws about 5mA at 2600 bytes/second of data input. Since that is too low for USB to work, I upload data files and set up tests by setting some EEPROM values in...
    1 replies | 48 view(s)
  • mborgerson's Avatar
    02-10-2020, 08:06 PM
    I didn't realize that the forum display didn't like my tab settings. Here is an easier-to-read version of the results table: Algorithm mA with no sync mA with sync() ———————————————————————————...
    7 replies | 116 view(s)
  • mborgerson's Avatar
    02-10-2020, 07:59 PM
    While working on a project to build a low-power data logger using a Teensy3.6, I discovered something a bit counter-intuitive. I found that calling the sync() function after writing a block of data to the output file...
    7 replies | 116 view(s)
  • mborgerson's Avatar
    01-10-2020, 05:04 PM
    The concern for writes of less than 512 bytes goes back to the original implementation of the LFS on an MSP430F148, which has only 2KB of RAM. There are only two allocated sector buffers in the LFS, one for the...
    13 replies | 277 view(s)
  • mborgerson's Avatar
    01-09-2020, 07:05 PM
    I've done some more tests with transferStop and I find that it does indeed reduce power drain significantly: on a T3.6 at 24MHz using a 32GC SanDisk Ultra SD micro card. After SDC.begin but before any calls to...
    13 replies | 277 view(s)
  • mborgerson's Avatar
    01-04-2020, 04:23 AM
    I'm working on a Teensy version of a Logger File System (LFS). It is a sequential file system with a simple directory structure and minimal file system overhead. It was originally written for data loggers using MSP430...
    13 replies | 277 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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Recommendation for piezo buffer op-amp 02-12-2020 05:49 PM
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02-02-2018