Go to advanced search

by ElEscalador
Fri Feb 21, 2020 8:41 pm
Forum: Beginners
Topic: How do I read serial via GPIO pins
Replies: 4
Views: 131

Re: How do I read serial via GPIO pins

You can bitbang (make a software uart) with any of the GPIO pins but I save that until I've used the UART tx/rx (pins 14 and 15). Try /dev/Serial0 or /dev/Serial1...but do read the docs for configuration info. You can also use a USB to TTL converter - usually whats called an FTDI and use the USB fro...
by ElEscalador
Fri Feb 21, 2020 3:04 pm
Forum: General discussion
Topic: usb camera vs PI camera with OpenCv and raspberry pi 4
Replies: 7
Views: 234

Re: usb camera vs PI camera with OpenCv and raspberry pi 4

I'm not sure..I know rendering that way would be slower than playing directly since imshow is not a free process. Maybe for the testing of cameras you'd be better to try a program like cheese and avoid any opencv-related slowdowns. If it's fast enough in cheese than I'd guess the opencv processes of...
by ElEscalador
Fri Feb 21, 2020 2:15 pm
Forum: General discussion
Topic: usb camera vs PI camera with OpenCv and raspberry pi 4
Replies: 7
Views: 234

Re: usb camera vs PI camera with OpenCv and raspberry pi 4

I don't know how fast you need, but it's far more likely the processing of the frames is going to be the choke-point, not the camera. Do you need more than 30 fps if you can only process 3-10?
by ElEscalador
Fri Feb 21, 2020 1:55 pm
Forum: Beginners
Topic: Interfacing ADS1115 ADC with Raspberry PI
Replies: 4
Views: 141

Re: Interfacing ADS1115 ADC with Raspberry PI

The spec sheet says "WIDE SUPPLY RANGE: 2.0V to 5.5V" so I'd say it good.
by ElEscalador
Fri Feb 21, 2020 1:52 pm
Forum: Automation, sensing and robotics
Topic: Help with Raspberry Pi Controlled Robot
Replies: 3
Views: 116

Re: Help with Raspberry Pi Controlled Robot

Why not use a motor controller designed to take a PWM signal (speed control) and direction signals directly from the Pi?
https://www.amazon.com/s?k=cytron+motor ... _sb_noss_2
by ElEscalador
Thu Feb 20, 2020 11:30 pm
Forum: Automation, sensing and robotics
Topic: Fooling a CT Clamp Sensor
Replies: 2
Views: 229

Re: Fooling a CT Clamp Sensor

The ones I've seen just produce a voltage in scaled response to current. You might start by measuring the voltage at various currents you also measure (or read) and make yourself a map - it's probably a linear relationship. With that, you can fake analog voltage out with PWM, but I'm not sure how mu...
by ElEscalador
Thu Feb 20, 2020 4:49 pm
Forum: Automation, sensing and robotics
Topic: MPU-9250 Magnetometer Wide Range of Values
Replies: 3
Views: 109

Re: MPU-9250 Magnetometer Wide Range of Values

Motors make wicked big magnetic fields and even saturating the magnetometer itself and then turning the motors off it can take a while before the magnetometer ever reads the uncorrupted reading again. Generally speaking, magnetometers are not really useful for indoor robots - too many metal things t...
by ElEscalador
Wed Feb 19, 2020 3:11 pm
Forum: Automation, sensing and robotics
Topic: Magnetometer Project
Replies: 7
Views: 1126

Re: Magnetometer Project

Magnetometers don't "switch" when in the presence of a magnetic field - they output a measurement of the field (in x, y, and z directions). So you don't ened one with "adjustable sensitivity" you just need to write your code to consider a reading of some value you define as "this much be a car." It ...
by ElEscalador
Tue Feb 18, 2020 2:49 pm
Forum: Automation, sensing and robotics
Topic: Acs712 current sensor
Replies: 6
Views: 143

Re: Acs712 current sensor

cgriggry wrote:
Tue Feb 18, 2020 2:42 pm
I am using it to sense a light bulb to send an email, so I need it as accurate as I can get.
You want to send an email when the light bulb comes on? There are far easier ways than an ADC. It might help us if you're a little more specific about what you are trying to do.
by ElEscalador
Mon Feb 17, 2020 12:54 pm
Forum: Automation, sensing and robotics
Topic: Difficulty with automated bots
Replies: 1
Views: 109

Re: Difficulty with automated bots

First, let me suggest that you almost certainly want to use ROS (or other robotics framework). I tried to avoid it at first but ended the amount of data that has to be shared between so many separate components for an autonomous robot is tremendous and spent most of my time trying to write a program...
by ElEscalador
Sun Feb 16, 2020 2:27 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Problem with the Ublox neo 6M gps
Replies: 12
Views: 329

Re: Problem with the Ublox neo 6M gps

bensimmo wrote:
Sun Feb 16, 2020 6:56 am
look at /dev/serial0 and not the ttyAMA0 or ttyS0
It will point to the correct place if you use raspi-config's (or the desktop version) settings to enable the serial port and disable the serial console.
Ah right. I haven't used Raspian flavors in forever.
by ElEscalador
Sun Feb 16, 2020 12:51 am
Forum: Automation, sensing and robotics
Topic: can i use a relay backwards ?
Replies: 4
Views: 203

Re: can i use a relay backwards ?

Yes - the relay doesn't care which way the current is flowing and they are used all the time in commercial controls to toggle a machine from automatic to manual control - where the load is hooked up to common and two possible sources of energy are on the no/nc pins. Insert warning statement about sa...
by ElEscalador
Sun Feb 16, 2020 12:47 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Problem with the Ublox neo 6M gps
Replies: 12
Views: 329

Re: Problem with the Ublox neo 6M gps

Once you get it bootable again, as topguy suggested trying using only the raspi-config to disable the serial console. When that's done, plug in your gps to the uart pins 14 and 15, as well as supplying it 3.3v and ground from the pi. It should show signs of life... in any case, before you mess with ...
by ElEscalador
Sat Feb 15, 2020 12:02 am
Forum: General discussion
Topic: Is a Neodymium magnet a viable Raspberry Pi mount
Replies: 1
Views: 209

Re: Is a Neodymium magnet a viable Raspberry Pi mount

Yes and no. I've used magnets a few times where I wanted to be able to move PIs. Often all was just fine, but there is some point where too strong a field will prevent a PI (proven on a zero, at least) from booting. Here was my PSA and findings from a while back https://www.raspberrypi.org/forums/vi...
by ElEscalador
Sat Feb 08, 2020 2:34 pm
Forum: Troubleshooting
Topic: Magnetometers problem...
Replies: 4
Views: 111

Re: Magnetometers problem...

The standard solution is to move the imu as far as possible from these sources. I did notice as a kid that copper interfered with magnetism and have wondered if it could be used to block or minimize the distortion from something like motors, but have not spent any time looking into it. (if it would ...
by ElEscalador
Sat Feb 08, 2020 1:42 pm
Forum: Troubleshooting
Topic: How do I get data from my car?
Replies: 3
Views: 148

Re: How do I get data from my car?

U.S. cars since 199-something should have an OBD2 connector and interface - not sure about elsewhere. That makes it easy to plug in an inexpensive Bluetooth adapter. There might be better resources than reverse engineering an android app, but there are several to choose from that interface and read ...
by ElEscalador
Sat Feb 08, 2020 1:33 pm
Forum: Troubleshooting
Topic: Magnetometers problem...
Replies: 4
Views: 111

Re: Magnetometers problem...

I didn't study it closely but this looks like a decent primer.
https://appelsiini.net/2018/calibrate-magnetometer/
by ElEscalador
Sat Feb 08, 2020 1:31 pm
Forum: Troubleshooting
Topic: Magnetometers problem...
Replies: 4
Views: 111

Re: Magnetometers problem...

What software are you using to get an "angle?" Magnetometers have to be calibrated in place on their machine because parts on the machine will warp the magnetic field. If it's too close to motors the cause will be hopeless (it sounds like its too close to something on your machine that has a strong ...
by ElEscalador
Sat Feb 08, 2020 1:02 am
Forum: Automation, sensing and robotics
Topic: Tennis ball collector
Replies: 24
Views: 1146

Re: Tennis ball collector

That's fair - I'm all about doing things for the challenge.
by ElEscalador
Fri Feb 07, 2020 3:05 pm
Forum: Troubleshooting
Topic: raspberry pi, L298N motor driver with 12v 8amp battery
Replies: 5
Views: 142

Re: raspberry pi, L298N motor driver with 12v 8amp battery

There's plenty out there but this one and the ten-amp version by the same company have served me well. https://www.amazon.com/gp/product/B01M4 ... UTF8&psc=1
by ElEscalador
Fri Feb 07, 2020 12:39 pm
Forum: Automation, sensing and robotics
Topic: 12v door lock using usb port
Replies: 2
Views: 151

Re: 12v door lock using usb port

Almost certainly not. Electromagnets take a lot of power - you could do something like use stepped-up and current-limited power from the PI's USB port to trickle-charge a 12v battery or something, but that's a ridiculous complication compared to just using a 12v supply to the door lock and a relay a...
by ElEscalador
Fri Feb 07, 2020 12:33 pm
Forum: Automation, sensing and robotics
Topic: Tennis ball collector
Replies: 24
Views: 1146

Re: Tennis ball collector

When it's time to move up from a Pi3 because you need more speed for image processing, it's time to skip the Pi4 and move right to the Nvidia Jetson Nano. A few $ more and many times faster. Make that "many, many, many times faster" if you run your processes on the 128 core GPU.
by ElEscalador
Thu Feb 06, 2020 3:42 pm
Forum: Automation, sensing and robotics
Topic: AlphaBot + Raspberry Pi 4 issues
Replies: 6
Views: 188

Re: AlphaBot + Raspberry Pi 4 issues

The Pi 4 has all sorts of shortcomings and packages not prepared for it that I find it far too big a pain to work with for robotics except where I have to. Especially since it really doesn't provide any real benefit for most basic robot applications and consumes a lot more power. I don't know anythi...
by ElEscalador
Thu Feb 06, 2020 1:32 pm
Forum: Beginners
Topic: Fitting a fan without using GPIO?
Replies: 20
Views: 424

Re: Fitting a fan without using GPIO?

It's a petty pet peeve of mine that we can't get a couple of pins for a fan without interrupting access to the entire header. The choices are to splice into your ribbon cable, find a place on the board to solder to, or power via USB - you can get little US breakouts with screw terminals.

Go to advanced search