[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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