[carpe] 2017-09-26 CARPE Conscribillati: donkey car; I2C level shifting; link farm

jep200404 at columbus.rr.com jep200404 at columbus.rr.com
Tue Sep 26 16:52:05 EDT 2017


DIY autonomous car (that uses Python)

    Donkey Car
    http://www.donkeycar.com/

http://www.autonomyhub.com/workspace
http://www.autonomyhub.com/events
https://www.meetup.com/AutonomyHub/

    Joint Meetup with VR Columbus: VR demo and robotics racing in the works
    https://www.meetup.com/AutonomyHub/events/243521906/

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Texas Instruments' TCA9406 chip is great for interfacing I2C chips at voltages
other than 3.3 V, such as the Melexis MLX90621 sensor that wants to interface
at 2.6 V. The edges are very fast, so it works very well at 1 MHz, not just 100
kHz.

    http://www.ti.com/lit/ds/symlink/tca9406.pdf
    https://www.melexis.com/-/media/files/documents/datasheets/mlx90621-datasheet-melexis.pdf

The TCA9406 is much better than using FETs as in Philips/NXP's application note
"Level shifting techniques in I2C-bus design" AN10441.

    http://www.nxp.com/docs/en/application-note/AN10441.pdf

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    2016-11-29

    Second prototype interface works great.
    It works well at 1 MHz as well as the default (100 kHz?)
    The TCA9406 chip worked great.

    Rise and fall times

        at sensor chip

            scope probe clipped directly to legs of MLX chip.

            SCL
                fall: 10 ns
                rise: < 50 ns

            SDA
                fall: 10 ns, 80 ns
                rise: 40 ns

        at 40-pin connector of interface board
        at end of 17 inch long 40-pin ribbon cable

            scope attached indirectly to 40-pin connector
            with daintly clip cables that were each 20.5" long

            SDA (from pin 9 to pin 3)
                fall: 10 ns, 55 ns
                rise: 40 ns

            SCL
                fall: 10 ns
                rise: forgot to write it down. it was quick enough

    power supply at MLX chip:

        2.594 V with DMM

        120 mVpp noise on power observed with 'scope

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Packet radio lives on through open source software
https://opensource.com/article/17/9/packet-radio

$17 RPi HAT features 8-channel ADC and industrial temps
http://linuxgizmos.com/17-raspberry-pi-hat-features-8-channel-adc/

Arduino unveils tiny, battery powered MKR boards for LoRa and 3G
http://linuxgizmos.com/arduino-unveils-tiny-battery-powered-mkr-boards-for-lora-and-3g/

Ubuntu Touch OTA-2 Rolls Out for Ubuntu Phones, Including Nexus 4 & Nexus 7 2013
Nexus 4, Nexus 5, Nexus 7 2013 (Wi-Fi only), OnePlus One, and Fairphone 2
http://news.softpedia.com/news/ubuntu-touch-ota-2-rolls-out-for-ubuntu-phones-including-nexus-4-nexus-7-2013-517813.shtml

wp:List of open-source mobile phones

Le Potato
First Libre Computer Board AML-S905X-CC
https://libre.computer/2017/03/02/first-libre-computer-board/


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