5
Sure, longer pins do exist:
An alternative is to have male pins on one side and female pins on the other:
Searching for "GPIO 2x20" in your favorite shopping site should give you similar results.
In both cases, you may need an iron which is thin enough to go between the pins to make sure the solder flows evenly around each pin.
5
You might be interested in Stacking headers (eg: https://www.adafruit.com/product/85)
Several boards all with stacking headers can be connected on top of each other, including to a breadboard at the bottom of the stack too.
Photo example to illustrate, just an arbitrary google images result:
3
There are really two parts to this question. Can you boot from floppy, and can you put an OS on a floppy.
As to whether you can put an OS on a floppy, yes of course you can. Quite apart from the good old days of MS-DOS 3.1, CP/M, et al, I have written small OS that will run from a floppy, it isn't difficult.
As an intellectual exercise or learning process, ...
3
Callbacks are emitted by one thread. Each callback will therefore run to completion before the next is called.
This is true for RPi.GPIO and all the other Pi GPIO Python and C modules that I am aware of.
Treat callbacks as interrupts. Do the minimum possible before returning, e.g. set a flag to be picked up in the main thread.
3
Just for reference, there are two well-known approaches for addressing multiple keys with fewer pins: voltage ladder if you have analog pins and key matrix if you have digital pins. The Pi itself has no analog pins, but if you use an ADC, it's possible to use some of its channels for buttons.
Any non-standard wiring schemes are either suboptimal compared to ...
3
You asked, "How should I interface a solenoid to a RPi GPIO input?", and solicited some feedback on the schematic in your question:
Does the optocoupler circuit look like it will work (without destroying the GPIO)? Are there any potential pitfalls I have missed? Is there a more sensible approach to detecting the doorbell press?
General Answer:
...
2
I found an online simulator here, but you can't modify the hardware: https://create.withcode.uk/python/A3
https://fritzing.org/ has hardware and code, but I have not tried the coding yet. It costs about $9 but is worth it in my opinion. They also have the option to create and upload your schematics and will send you a PCB board (for a fee).
2
See gpioSetAlertFunc. Do the maths to work out how often a 400 nanosecond pulse will be picked up.
For short pulses use gpioSetISRFunc. That will pick up pulses a few nanonseconds long.
2
It is unclear exactly what you have done (list full code & connections).
What is R_US
The fundamental problem is your circuit.
Using an emitter follower is POOR practice; it will attempt to put 2.7V across the LED when ON, overloading the GPIO with unpredictable results. You have shown the LED connected in reverse.
Try a more conventional circuit; the ...
2
You could try something like the following - which will at least isolate buttons.
Pushing the centre button will activate both inputs - the others a single input. Strictly no diode is required on the isolated buttons.
simulate this circuit – Schematic created using CircuitLab
1
You can get extended headers - I use these on my Pico so it plugs into a breadboard but still has accessible pins.
NOTE this will not let you use 2 HATs (as the pins would be inverted).
The normal solution is to use extended headers on the HAT.
1
You can only control two servos independently with the Pi's hardware PWM.
GPIO 12/18 share a channel.
GPIO 13/19 share a channel.
The same settings apply to GPIO which share a channel.
E.g. If servo1 is on GPIO12 and servo2 on GPIO18 they will get the same signal (same frequency, same pulsewidth).
pigpio supports the hardware PWM features of the Pi. So you ...
1
This is an EE Question, not Pi specific.
What you propose should work (depending on current transfer ratio of opto-isolator - which should be adequate).
I can see only one potential issue - the snubber diode may impact on the ding on release.
If so, you could protect the opto-isolator by connecting the diode across the opto-isolator input (D2 in your diagram)...
1
Shorting 5V with GND only really stresses the power supply, and, depending on the Pi model, the polyfuse. After a cooling down time, everything should work again.
However, it's pretty much impossible to know what else was shorted in your setup. mpu6050 is a 3.3V device, so applying 5V on any of its pins has a good chance of destroying it.
1
I endorse joan's comments.
It is simple to control a fan with inexpensive circuit.
See https://raspberrypi.stackexchange.com/a/105820/8697
See https://docs.google.com/document/d/1bxIzUXLXdrtTo7DwAYv8maLeBssYau4nWwyeAAjot-0 for a picture of my module.
1
You should NEVER connect a GPIO to an inductive load. Eventually you will destroy the GPIO and the Pi.
You should NEVER connect a GPIO to a voltage outside the range 0 to 3.3 volts. Eventually you will destroy the GPIO and the Pi.
A GPIO can only supply (source or sink) about 20 milliamps at 3.3 volts. Nowhere near enough to power a motor even if it was ...
1
I was able to fix the pip3 install RPi.gpio with this:
export CFLAGS=-fcommon
pip3 install RPi.GPIO
Source: https://www.raspberrypi.org/forums/viewtopic.php?t=289084
1
Reduce or remove bouncetime=200 entirely in
GPIO.add_event_detect(button, GPIO.BOTH, callback=buttonpressed, bouncetime=200)
Then in your callback, add a static variable and a condition statement that will accept the input only if the edge is different from the previous one :
def buttonpressed(channel):
if "previous_edge" not in buttonpressed....
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