We’re rewarding the question askers & reputations are being recalculated! Read more.
3

There's nothing wrong with putting a thermocouple on the chip heatsink like this. You can still damage the Pi if the rest of your setup is inappropriate: for instance if your thermocouple wiring is exposed to ESD or it is powered by a non-isolated power supply (though in the latter case I would worry about my own health more). If the temperature sensor is ...


3

Run (my) gpiotest or run wiringPi's pintest. For both tests nothing should be connected to the expansion header.


3

To add to @Ghanima's excellent answer, you may also wish to consider a latching relay. Briefly, a latching relay has two stable states (i.e. it is a bistable device, similar to a flip-flop). This means that the relay can be latched into an OPEN or CLOSED state, and it will remain in that state until commanded to change by the input. This avoids the necessity ...


3

The first stop to answer such questions should be the datasheet of the part in question. This is where the manufacturer lists the operating conditions of the device. That aside it is usually safe to have a relay active for longer periods of time, assuming you're within the operational range of current and voltage (again, as laid out in the datasheet). ...


2

You can not "control" a standard DC motor directly from the Pi. If you connect a standard DC motor to the Pi's 5V and ground pins the motor will be running at a fixed speed, in a fixed direction, for as long as the Pi is powered. Even this makes the gross assumption that the 5V pin is high enough in voltage and can supply enough current to move the motor ...


2

You've not mentioned which Pi you have but on some models the green/amber activity/status LED comes on at boot and goes off at shutdown, you could monitor that either by removing the LED and soldering wires to the pads or maybe an optoswitch of some sort. A slightly better solution might be to monitor the TX line on the GPIO as described here. Again, you've ...


2

The spec mentions PWM and a 16:1 scan rate, so each LED would only be on for 1/16 of the time.


2

According to this datasheet for the STC-013, the output voltage ranges between 0 and 50 mV for 0 to 100A. An increase of 2/1023*5 gives a measured voltage of around 0.009 V, or 9 mV, which would suggest a current of around 0.9 A. The readings you're getting seem reasonable, just not terribly helpful. In this sort of situation, I believe you can use an op-...


2

What you're looking for is commonly called a solid-state relay (SSR.) SSRs combine solid-state switching of AC power (via a triac) with optical isolation (between the control signal side, vs. the load side), so they're pretty safe if (and only if) you get one rated well above the voltage and current you plan to control. I'd suggest keeping to models with ...


2

One can find many more wirelessly controlled sockets in the market, nevertheless, there are also some based on control via Ethernet. Here is one example. Typically they are more pricy than Wifi-controlled sockets. Depending on the modell they offer different interfaces for control (Windows application, web interface, ...). The one linked above for example ...


2

I2C: Inter-Integrated Circuit, used for communicating between chips on the same PCB. Allows multi-master, multi-slave configuration, slower than SPI. This is a two-wire bus. No two devices can have the same slave address on a single bus. SPI: Serial Peripheral Interface, used for communicating with external devices (chips, sensors, displays etc). Much ...


2

It depends on the microcontroller and what purpose you need out of it. However, most microcontrollers use ICSP or serial UART as a programming interface. Therefore, at the minimum, you would need UART. UART is also trivial to implement in most DIY programs. In most cases, you will simply need to read and write strings to an interface (e.g. \dev\ttyX on RPi, ...


2

You need to connect the ground of the two Pis together as well as any GPIO you want to use for data transfer. If the grounds are not connected the Pis can not tell if a GPIO is set high or low by the other Pi. As @Arnaud suggests it would be sensible to add a resistor somewhere in-line between each Pi GPIO to other Pi GPIO connection. Something of the ...


2

For Fans with integrated PWM controllers Good practice is to install a single series resistor (50-100Ohm) to limit the current in case of accidental short circuit or failure of the fan. No additional hardware is necessary, and if you can tollerate that risk it will be fine for reasonable <1M long GPIO cables without a series resistor. Note that some ...


2

I think the IRLZ44N transistor is extreme overkill for the fan you're using. The blog you've quoted is lacking in important hardware details (I've not read his code), but it appears he's just ON-OFF banging a 2-wire fan with a GPIO pin driving a MOSFET. I'd counsel some caution in following the approach outlined here, but I may be a bit biased by people who ...


1

I did a similar project with a Power Wheels Wild Thing and an Arduino. I settled on buying a couple of BTS7960B motor controllers. They are rated for 43 amps, and I assume they will work for a Pi though I haven't done it myself. Someone used these controllers on a Pi, they may have some helpful pointers. Below is a simple diagram showing how to hook it up. ...


1

Question How much current is required for a 64x32 LED matrix? Spec says 4A max at 5V, when all LEDs (SMD3528 16mA) on Why not 16mA x 64 x 32 ~= 32A? Short Answer How the LED matrix works Well, when they say "all LEDs on", they are a bit misleading. Actually they are "scanning" the LEDs. Each LED is only repeatedly on for a short ...


1

Are RC snubbers needed in this kind of use case for safety? Well, when the relay switch contact breaks, current (of inductive load storing the inductive energy) has no where to go and therefore crazily fly across the contacts of the relay switch, in the form of a spark. The sparks would shorten the life of the silver contact points of the relay switch. ...


1

It is perfectly save to hold the RUN pin low. There seems little point, because as goldilocks says it will be in the halt state. The GPIO pins also retain their state (which can be used by gpio-poweroff to signal this state). It presumably will use less power (which is small anyway) if the RUN pin is low because this will prevent the Video Core from ...


1

I'm getting error 401 with your Front Panel I/O link, but what you're trying to do seems simple enough. There are two main ways I would recommend to do this: If you want to use a transistor, I would suggest using an NPN BJT; a 2n2222 should work well. The circuit is identical for each switch, with the transistors' collectors connected to PWR_SW_P and ...


1

It seems your L298N is damaged. A switch can never cause this much problem. Try to power raspberry and the module seperately. You r circuit shows that the power of raspberry is drawn from the module thorugh the regulator on the module.


1

You can set the Pi to assert a GPIO output on poweroff. dtoverlay=gpio-poweroff This is intended for use with external power circuitry. There are many pins which may or may not provide a reliable indicator, but in general GPIO pins retain their state when shutdown so do not provide a reliable indicator. See https://raspberrypi.stackexchange.com/a/89298/...


Only top voted, non community-wiki answers of a minimum length are eligible