21
votes
pigpio Can't lock /var/run/pigpio.pid
You need to stop the pigpio daemon if you run a program directly linked with the pigpio C library.
In effect your program becomes the pigpio daemon and only one may be running at a time.
So
sudo ...
- 70.4k
15
votes
Raspberry as an I2C SLAVE
Since this topic is very poorly covered and Sebastião's snippet
and helped me to solve this problem I want add a complete solution on how to setup a RaspberryPi right here (tested on a RPi 3 and Zero ...
- 151
9
votes
Accepted
pigpio - set_PWM_dutycycle vs hardware_PWM
hardware_PWM >>> set_PWM_dutycycle >>> software PWM
where >>> is orders of magnitude better pulse stability.
hardware_PWM
rock solid pulses
large choice and range of frequencies
large number of ...
- 70.4k
7
votes
Accepted
Raspberry as an I2C SLAVE
This is almost identical to your previous question. You probably should have edited that rather than asking a new question.
You need the bscXfer to be within the while loop. That is how the xfer ...
- 70.4k
6
votes
Accepted
gpiotest problem and gpio 30
That is a fault in pigpio/gpiotest and/or the hardware revision returned by the Pi Zero W.
gpiotest relies on pigpio to tell it which GPIO are safe to write.
pigpio relies on the hardware revision ...
- 70.4k
6
votes
Accepted
Is there a way to read the pullup status of a GPIO pin in python with, or if not, without pigpio?
It is not possible.
Page 100 of BCM2835 ARM Peripherals
GPIO Pull-up/down Register (GPPUD)
SYNOPSIS
The GPIO Pull-up/down
Register controls the actuation of the internal pull-up/down ...
- 70.4k
6
votes
Accepted
Is there a GPIO current limit function available, and where is the documentation?
Yes. The definitive source for RPi hardware documentation is the Raspberry Pi Foundation. The Foundation updated their published documentation to include programmable GPIO current limits recently (Jan,...
- 20.7k
5
votes
How to read Wiegand card ID?
You can reliably read Wiegand devices with my pigpio library.
There is C, C++, and Python example code at http://abyz.me.uk/rpi/pigpio/examples.html
- 70.4k
5
votes
How to use piscope from my pigpio library on python
If you are running piscope on a Pi enter the following commands.
sudo pigpiod # Start the daemon if not already running.
piscope & # Run piscope in the background.
The main piscope display will ...
- 70.4k
5
votes
Accepted
How does pigpio's wave_chain() method happen in hardware?
The Raspberry Pi has 16 hardware DMA (Direct Memory Access) channels.
Using DMA you can copy the contents of memory from one memory address to another memory address without software involvement. ...
- 70.4k
5
votes
Is there a way to slow down servo movement speed?
This may work as an example, give it a start and end position, and the time(seconds) you want it to take to move there. It will break the movement up into 100 incremental moves this will slow down ...
- 1,043
4
votes
Accepted
pigpio PWM and ALSA
By default pigpio uses the PCM peripheral to time the DMA leaving the PWM peripheral free for standard audio.
Perhaps your ALSA device is using high quality audio. If that's the case you need to use ...
- 70.4k
4
votes
Accepted
Does pigpiod feature a verbose / debug mode?
Errors are reported to /dev/pigerr on the Pi running the daemon.
So cat /dev/pigerr may provide useful information.
You can enable tracing of the API by using the pigs csi command.
Numbers 1 to 7 ...
- 70.4k
3
votes
python library to generate pulse frequency of "n" hz
Actually the pigpio Python module can do this quite easily for a single stepper.
You would use the wave functions in combination with wave chains.
Say you want a ramp of 20ms, 10ms, 5ms, 2ms, 1ms.
...
- 70.4k
3
votes
Accepted
12v+ on Raspberry Pi Ground Pin
It sounds like you were lucky in that the Pi appears to still work.
To test the GPIO use either my gpio test (requires pigpio) or wiringPi's pintest utility.
These test the basic GPIO functions.
- 70.4k
3
votes
Accepted
pigpio = DHT22 humidity sensor + TMP36 readings PROBLEM
Okay, you are using GPIO 8 to power the DHT22.
GPIO 8 is actually the chip select for channel 0 of the main SPI device.
So choose another GPIO, or power the DHT22 from 3V3 and set the power ...
- 70.4k
3
votes
Counting Pulse Length Using PiGPIO
I'm not going to delve too deeply into the code.
I had a look at the datasheet and it seems to encode the reading in the low time over some sort of interval. It seems a little light on details.
A ...
- 70.4k
3
votes
pigpio servo control
The only problem I can see with the code is that it terminates straight away.
When the program ends the pigpio library will shut down so servo pulses will stop.
I suggest you add a time_sleep(10) or ...
- 70.4k
3
votes
Accepted
Measure rpm using hall sensor and pigpio
Q1
I don't remember but the code may well use a rolling average to calculate the RPM. This helps smooth the data.
Q2/3
The code as given is instantiated with
p = read_RPM.reader(pi, RPM_GPIO)
...
- 70.4k
3
votes
2 pigpio programs at the same time
Only one program linked against the C library (pigpio) can be running at any one time. This program in effect becomes the pigpio daemon.
Many programs can talk to the pigpio daemon at the same time ...
- 70.4k
3
votes
Accepted
High speed bit bang GPIO reading
I do not remember why the limit is 250k rather than say 500k or 1000k. I expect there was a reason. It may simply have been there was too much jitter at the higher bit rates to reliably clock the ...
- 70.4k
3
votes
Accepted
pigpio spiXfer in C++
Using a char type to hold bytes is fairly common in C. char is one of the basic C types and holds one byte.
Here is some C code to read channel 0 of the MCP3008. The example should make clear how ...
- 70.4k
3
votes
Two data parsing frames for SPI reads of MCP3008 ADC, any advantages or disadvantages of either one?
The difference is whether you put the padding on the left or the right side of the data. The Adafruit implementation seems to start sending data immediately, which leaves the last 7 bits as padding, ...
- 119
3
votes
Any way to add more GPIOs to the AIY Voice Kit?
You can use a break-out board like the Black HAT Hacker or Pico HAT Hacker.
Alternatively, connect another Pi Zero as a USB gadget and use the GPIO expander.
- 2,431
3
votes
Accepted
pigpiod callback is exiting my code
As the code is written in your question, it is creating an unlimited number of callbacks. Eventually the system will fall over because of a lack of resources.
Also a pigpio callback receives a set ...
- 70.4k
3
votes
Segmentation faults on every GPIO STR
You get the error because you didn't map the IOBASE address range to your process' address space. Accessing an unallocated address is exactly what a SEGFAULT is.
Check the source code of any GPIO ...
- 27.6k
3
votes
Accepted
High Impedance state for GPIO
Tri-state output circuitry as used for most computer busses can be set Low, High or HiZ. In fact many circuits actually have 4 states as they can be set as Inputs. The state of a bus (consisting of a ...
- 58.2k
3
votes
Accepted
Full duplex SPI communication with an ADC using the pigpio library
If you want to send 8 NOP bits send a byte containing 0xFF.
count, rx_data = spi_xfer(handle, [0xff])
If you want to send 16 NOP bits send two bytes containing 0xFF.
count, rx_data = spi_xfer(handle, [...
- 70.4k
3
votes
Accepted
How fast are C & Python libraries
I wrote programs for a number of libraries, both c and python.
These just toggle a GPIO pin as fast as possible.
NOTE In case anyone misunderstands I am aware this is an artificial test with no real ...
- 58.2k
3
votes
Accepted
How to correctly identify the pin addresses in the Pi4J 2.2.1 GPIO API?
There are 3 pin numbering conventions in use on the Pi; BCM, Physical (or Board) and WiringPi.
BCM is the native numbering (and is the only convention understood by the SoC).
Board numbers correspond ...
- 58.2k
Only top scored, non community-wiki answers of a minimum length are eligible