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by amcdonley
Tue Nov 12, 2019 2:54 pm
Forum: Troubleshooting
Topic: Cannot determine i2c baud rate on rpi 3
Replies: 16
Views: 4747

Re: Cannot determine i2c baud rate on rpi 3

You can get the current value with something like this: ... Thanks - I put your code into a file i2c_baudrate.sh (then chmod +x i2c_baudrate.sh): #!/bin/bash # Print current maximum i2c rate var="$(xxd /sys/class/i2c-adapter/i2c-1/of_node/clock-frequency | awk -F': ' '{print $2}')" var=${var//[[:bl...
by amcdonley
Thu Sep 26, 2019 11:24 am
Forum: Troubleshooting
Topic: Odd WiFi Drop Out Issues
Replies: 13
Views: 560

Re: Odd WiFi Drop Out Issues

You did set static ip in the Pi and dedicated ip in the router, correct?

Check the router log for events with the MAC address.

Did you try a stretch Os and don’t do an update? There may be some weird things from the 4.19 kernel.
by amcdonley
Wed Sep 25, 2019 2:01 pm
Forum: Troubleshooting
Topic: Where to report ALSA cutoff issue after Stretch update?
Replies: 1
Views: 85

Where to report ALSA cutoff issue after Stretch update?

I see that lots of people are having "XXX cutting off", where XXX:{aplay, espeak, espeak-ng, ...}, after updating Stretch to Linux 4.19.66-v7+ #1253 SMP Thu Aug 15 11:49:46 BST 2019 armv7l (and also some Buster folks). aplay /usr/share/sounds/alsa/Front_Center.wav cuts off at "Front Cen" in my case....
by amcdonley
Mon Sep 23, 2019 8:35 pm
Forum: Automation, sensing and robotics
Topic: Raspberry Pi model 3B video processing speed
Replies: 5
Views: 437

Re: Raspberry Pi model 3B video processing speed

Interesting, so the CPU loads were 1.5%-2% yet temperature was high? PS/ Your link doesnt work well Thanks. Fixed the link. Not %. Load average is some weird number that seems to correspond to the number of cores in use when the number is less than the number of available cores. So 1.5 is an averag...
by amcdonley
Mon Sep 23, 2019 12:27 pm
Forum: Automation, sensing and robotics
Topic: Raspberry Pi model 3B video processing speed
Replies: 5
Views: 437

Re: Raspberry Pi model 3B video processing speed

This is my analysis of motion detect on a “non-aspirated” Pi 3B Video Surveillance (TL:DR 10fps heat limited) My testing of “Recognition” such as faces, color and size, lane markings run around 1 FPS. All these are single threaded Python3 with “stock packaged” OpenCV. One multi-processing test resul...
by amcdonley
Mon Sep 23, 2019 1:49 am
Forum: Troubleshooting
Topic: aplay and espeak issues after (Stretch) OS update
Replies: 0
Views: 75

aplay and espeak issues after (Stretch) OS update

I had aplay and espeak (text-to-speech) working great for the last year, until this week I executed the OS update sequence: sudo apt-get update sudo apt-get upgrade $ uname -a Linux Carl 4.19.66-v7+ #1253 SMP Thu Aug 15 11:49:46 BST 2019 armv7l GNU/Linux Now aplay is cutting off the last part of a w...
by amcdonley
Mon Sep 23, 2019 1:27 am
Forum: Troubleshooting
Topic: espeak doesnt work
Replies: 10
Views: 796

Re: espeak doesnt work

After updating my Raspbian Stretch: ``` Linux Carl 4.19.66-v7+ #1253 SMP Thu Aug 15 11:49:46 BST 2019 armv7l GNU/Linux ``` espeak stopped working completely for me. I got it to speak again by adding the following to my /home/pi/.bashrc ``` PA_ALSA_PLUGHW=1 export PA_ALSA_PLUGHW ``` (and rescanning i...
by amcdonley
Tue Sep 17, 2019 3:32 pm
Forum: Automation, sensing and robotics
Topic: How Many Sensors/Motors Can a Raspberry Pi 3 Handle at Once?
Replies: 6
Views: 363

Re: How Many Sensors/Motors Can a Raspberry Pi 3 Handle at Once?

power a small servo like the SG90, from the 5v gpio pin , probably 200mA max, (Corrected) "GPIO 5v pin" means one of the two 5v pins on the GPIO connector. The SG90 can draw 600-700 mA stall and instantaneous which can sag the 5v supply in some cases. It would be advisable to add a small 5v switchi...
by amcdonley
Sun Sep 08, 2019 4:44 pm
Forum: Automation, sensing and robotics
Topic: Challenge of Powering Robot 24/7
Replies: 6
Views: 343

Re: Challenge of Powering Robot 24/7

You should get a higher number of cycles with LiFePO4 cells. ... Some guys don't get enough for 24/7 from 30W ... It's a challenge.all right. The 8x NiMH AA cells fit in 4x4x1.25 inches and deliver 18-21 Watt-Hours (318mA idle * 9.6v nominal * 6 to 7 hours "fairly idle play time"). What allows 24/7...
by amcdonley
Sun Sep 08, 2019 4:26 pm
Forum: Automation, sensing and robotics
Topic: Challenge of Powering Robot 24/7
Replies: 6
Views: 343

Re: Challenge of Powering Robot 24/7

A dc-dc buck converter ... charging equalizers ... PS It would be just as interesting to explain how the charger works mechanically and how the robot locates it and plugs in. Yes, powering my bot would need some combination of converters, equalizers AND UPS function. The total requirements / constr...
by amcdonley
Sat Sep 07, 2019 3:48 pm
Forum: Automation, sensing and robotics
Topic: Challenge of Powering Robot 24/7
Replies: 6
Views: 343

Challenge of Powering Robot 24/7

For more than 20 years I have wanted my robots to become independent - managing their own charging to allow 24/7 operation. This year, with a GoPiGo3 robot, I substantially achieved this goal, and have learned more about the challenges facing a 24/7 robot. Specifically, in my case, the capacity of N...
by amcdonley
Mon Aug 26, 2019 7:16 pm
Forum: Automation, sensing and robotics
Topic: HDMI Off Power Saving Reality
Replies: 1
Views: 528

HDMI Off Power Saving Reality

After reading I could save 25mA by turning off the HDMI interface on my RPi 3B robot, with the command "sudo /usr/bin/tvservice -o", I was expecting to see my robot enjoying an extra 20 minutes of idle playtime. It would appear to be less than 6 minutes, or perhaps nothing at all when no display is ...
by amcdonley
Sat Aug 24, 2019 4:28 pm
Forum: Automation, sensing and robotics
Topic: Data Logging, Plotting Help
Replies: 9
Views: 1903

Local: Data Logging, Plotting

For simple logging sensor data to a file and then plotting it, all local: 1) Log Battery Voltage and Plot on linear scale by hour of day, and by time since first measurement 2) Log PiCamera Brightness Value and Plot on log scale by hour of day It is also possible to tie sensor readings into the RPi-...
by amcdonley
Mon Aug 19, 2019 7:16 pm
Forum: Automation, sensing and robotics
Topic: Simple Variable Sharing Between Python Processes?
Replies: 4
Views: 1239

Re: Simple Variable Sharing Between Python Processes?

You may consider a generic messaging queue (eg mosquitto) to communicate state changes across processes. I have to admit I am intimidated by the whole IoT complexity. I've watched rosie the red robot as he ventured there, but I have kept my distance. After 40+ years of doing commercial software sys...
by amcdonley
Mon Aug 19, 2019 6:28 pm
Forum: Automation, sensing and robotics
Topic: Simple Variable Sharing Between Python Processes?
Replies: 4
Views: 1239

Re: Simple Variable Sharing Between Python Processes?

SQLite3 doesn't support multiple writers. You very rapidly destroy your database if you get two writers running. Use python multi-threading to run everything in a single python process. Results on my Pi3B using multiprocessing pool.map to 3 "worker/inserter" processes that each obtain closing_lock/...
by amcdonley
Mon Aug 19, 2019 1:03 am
Forum: Automation, sensing and robotics
Topic: Simple Variable Sharing Between Python Processes?
Replies: 4
Views: 1239

Simple Variable Sharing Between Python Processes?

Right now I have a python module to manage concurrent access to some robot variables stored in a file "carlData.json" carlDataJason.py : * saveCarlData(dataname, datavalue, logit=False) # adds datanaem:datavalue to carlData.json file * getCarlData(dataname=None) # either returns dictionary with all ...
by amcdonley
Sat Aug 17, 2019 7:05 pm
Forum: Automation, sensing and robotics
Topic: Raspberry Pi High Frequency Sampling
Replies: 5
Views: 1475

Re: Raspberry Pi High Frequency Sampling

That is samples per second, not bytes per second. So if each sample was 12 bytes (4 bytes each of X, Y, Z) then that would be 20,000 times 12 or 240,000 bytes per second. The top line is 1 byte per second, the bottom line slower for 5 bytes per second, which implies 12 bytes per second will be even...
by amcdonley
Sat Aug 17, 2019 4:34 pm
Forum: Automation, sensing and robotics
Topic: Raspberry Pi High Frequency Sampling
Replies: 5
Views: 1475

Re: Raspberry Pi High Frequency Sampling

Hey guys, ADXL355 digital accelerometer over SPI and would like to sample at 4000hz. Does the pi have a maximum sampling rate cap, According to How Fast Is SPI the Linux SPI driver (in a C language program) seems to max out around 20K bytes per second. I don't know how many bytes each ADXL355 sampl...
by amcdonley
Fri Aug 09, 2019 10:43 pm
Forum: Troubleshooting
Topic: RPi 3B WiFi Down - recovered by unplug, replug dongle
Replies: 1
Views: 83

Re: RPi 3B WiFi Down - recovered by unplug, replug dongle

I think I see what happened - a few hours prior I did a: sudo rpi-clone sda and after it finished and unmounted both partitions, I unplugged the USB microSDcard adapter. Guess that did it. /var/log/messages: Aug 9 17:54:35 Carl kernel: [171141.137968] usb 1-1.4: USB disconnect, device number 5 Aug 9...
by amcdonley
Fri Aug 09, 2019 10:21 pm
Forum: Troubleshooting
Topic: RPi 3B WiFi Down - recovered by unplug, replug dongle
Replies: 1
Views: 83

RPi 3B WiFi Down - recovered by unplug, replug dongle

I just found my RPi 3B robot incommunicado by both wlan0 and wlan1 and this printed on the closed remote SSH login: packet_write_wait: Connection to 10.0.0.188 port 22: Broken pipe In spite of a solid blue light on the WiFi dongle, the RPI disk activity light seemed to indicate the bot was still run...
by amcdonley
Tue Aug 06, 2019 6:54 pm
Forum: Astro Pi
Topic: PiCamera as Luminosity Sensor?
Replies: 8
Views: 4416

PiCamera as Luminosity Sensor - Python Code Available?

Would love a post project report and to see luminosity sensor code.

I want to use PiCamera (v1.3) to measure room light level over 24hr periods - don't need calibrated value, just continuous values from darkness to brightly lit.
by amcdonley
Fri Aug 02, 2019 9:20 pm
Forum: Automation, sensing and robotics
Topic: Agree? “IMU worthless for simple robots' x, y, heading?”
Replies: 9
Views: 597

Re: Agree? “IMU worthless for simple robots' x, y, heading?”

You might be right but the question on the title I answered to was different than the one you are thinking at, since it did not had the "x, y heading" words at the end.. Kind of author changes its ckick-baity question then argues people gave him wrong answers, Please - I asked my question wrong, yo...
by amcdonley
Thu Aug 01, 2019 1:08 am
Forum: Automation, sensing and robotics
Topic: Robot Shared Values / DB impact on RPi SD card
Replies: 2
Views: 229

Re: Robot Shared Values / DB impact on RPi SD card

Thank you - great response. consider in memory databases https://en.wikipedia.org/wiki/List_of_in-memory_databases Or. if it suits you, a faster in memory key-value datastore like LMDB https://en.wikipedia.org/wiki/Lightning_Memory-Mapped_Database I have heard of, but know nothing about, SQLite whic...
by amcdonley
Wed Jul 31, 2019 8:32 pm
Forum: Automation, sensing and robotics
Topic: Agree? “IMU worthless for simple robots' x, y, heading?”
Replies: 9
Views: 597

Re: Agree? “IMU worthless for simple robots”

blimpyway wrote:
Wed Jul 31, 2019 8:09 pm
try to make a simple two wheel balancing bot (segway bot) without an imu.
Understandably impossible for the "keeping its head up" function, but can it provide accurate (world frame: x, y, theta)? It's a serious question. Am I wrong about that application of IMU?

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