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by joan
Mon Dec 11, 2017 8:14 am
Forum: Advanced users
Topic: Change GPIO pin state via command line
Replies: 4
Views: 149

Re: Change GPIO pin state via command line

Any number of ways.
  • write a small program interfacing with a GPIO library and make it executable.
  • write a shell script to use the sysfs interface to the GPIO.
  • use the wiringPi gpio utility.
  • use the pigpio pigs utility.
by joan
Sun Dec 10, 2017 8:37 pm
Forum: General discussion
Topic: Something changed
Replies: 23
Views: 559

Re: Something changed

How do you know you can not putty into the system?
by joan
Sun Dec 10, 2017 12:47 pm
Forum: General discussion
Topic: Measuring temperature using python.
Replies: 2
Views: 118

Re: Measuring temperature using python.

What temperature range?
by joan
Sat Dec 09, 2017 8:48 pm
Forum: General discussion
Topic: How to execute program on server without breaking security issues ?
Replies: 51
Views: 1358

Re: How to execute program on server without breaking security issues ?

Because you are trying to run error.log as a program. It is not a program, it is an error log, i.e. it is a text file containing errors. You need to view the messages.
by joan
Sat Dec 09, 2017 4:04 pm
Forum: Python
Topic: High frequency stepper motor
Replies: 1
Views: 95

Re: High frequency stepper motor

The hardware PWM (there are two channels) can certainly generate much higher frequencies (down to pulses a few tens of nanoseconds long). pigpio waves can work in that region (1µs resolution) and can keep count of the pulses transmitted if you use a wave chain. Have a look at http://abyz.me.uk/rpi/p...
by joan
Sat Dec 09, 2017 8:14 am
Forum: Troubleshooting
Topic: GPIO raspberry 3: I read all 0 on gpio
Replies: 2
Views: 137

Re: GPIO raspberry 3: I read all 0 on gpio

Use wiringPi's pintest utility or pigpio's gpiotest.

Either way, post your code.
by joan
Fri Dec 08, 2017 10:46 pm
Forum: General discussion
Topic: 433 Comms.
Replies: 2
Views: 132

Re: 433 Comms.

Have a look at http://abyz.me.uk/rpi/pigpio/examples.h ... on__433_py for sending numbers and perhaps http://abyz.me.uk/rpi/pigpio/examples.html#Python_vw for sending longer messages.

Both examples assume you have a reasonable familiarity with Python.
by joan
Fri Dec 08, 2017 11:10 am
Forum: General discussion
Topic: High Precision AD/DA board ADS1256
Replies: 7
Views: 288

Re: High Precision AD/DA board ADS1256

The Pi's 5V supply is unregulated. Unless you have found a way to make it stable it will be going up and down. You also need to check if the output pin of the ADC is also at 5V - that could harm the Pi.
by joan
Wed Dec 06, 2017 10:34 pm
Forum: General discussion
Topic: How to know PIGPIO demon working
Replies: 10
Views: 350

Re: How to know PIGPIO demon working

You don't have to use pigpio (unless you need a feature only it provides). There are many libraries which allow access to the GPIO.

See https://elinux.org/RPi_GPIO_Code_Samples
by joan
Wed Dec 06, 2017 9:57 pm
Forum: General discussion
Topic: How to know PIGPIO demon working
Replies: 10
Views: 350

Re: How to know PIGPIO demon working

The pigpio daemon is software which runs on a Pi. It is a server running on the Pi. It allows access to that Pi's GPIO. The access is via TCP sockets (network or local) or via a pipe (local). The daemon is used by pigs and the python and pdif modules. See http://abyz.me.uk/rpi/pigpio/index.html
by joan
Wed Dec 06, 2017 9:17 pm
Forum: General discussion
Topic: How to know PIGPIO demon working
Replies: 10
Views: 350

Re: How to know PIGPIO demon working

The pigs command is working which shows the daemon is running. You only need to start it once per boot. The sudo pigpiod error is indicating the daemon has already been started.

You should not use sudo with pigs. Only the daemon needs to be started with sudo.
by joan
Wed Dec 06, 2017 8:51 pm
Forum: General discussion
Topic: How to know PIGPIO demon working
Replies: 10
Views: 350

Re: How to know PIGPIO demon working

It may be installed. Try sudo pigpiod which will start the daemon if it is present.
by joan
Wed Dec 06, 2017 8:43 pm
Forum: Beginners
Topic: help with 1.27mm connector
Replies: 6
Views: 169

Re: help with 1.27mm connector

Perhaps find a header you can stick wires into?

https://www.gradconn.com/Products/BoardToBoard/1-27mm

Easier than soldering to the pins themselves.
by joan
Wed Dec 06, 2017 8:07 pm
Forum: General discussion
Topic: Which GPIO to use and other issues
Replies: 2
Views: 132

Re: Which GPIO to use and other issues

There are only a few Python libraries. See https://elinux.org/RPi_GPIO_Code_Samples The glaring omission is gpiozero which is a wrapper around the other libraries. Choose a library and spend time understanding what it does and how it works. If you do that you will have learnt enough to use any of th...
by joan
Wed Dec 06, 2017 7:35 pm
Forum: Beginners
Topic: help with 1.27mm connector
Replies: 6
Views: 169

Re: help with 1.27mm connector

Can you provide a photo of the connections?
by joan
Wed Dec 06, 2017 7:30 pm
Forum: General discussion
Topic: How to know PIGPIO demon working
Replies: 10
Views: 350

Re: How to know PIGPIO demon working

The simplest method is to issue a command. I use the following

pigs t

If you get a number the daemon is working.
by joan
Wed Dec 06, 2017 11:25 am
Forum: Advanced users
Topic: Using SMBUS to get something from a weird chip
Replies: 3
Views: 186

Re: Using SMBUS to get something from a weird chip

I would use (my) pigs to try out the commands. It allows you to issue commands from a shell and allows a quick test of what does and doesn't work. In practice a lot of chips do not actually need a restart condition to be sent on the line (and the drivers often automatically add a restart when needed).
by joan
Wed Dec 06, 2017 11:19 am
Forum: Beginners
Topic: Continuous rotation servo control.
Replies: 6
Views: 198

Re: Continuous rotation servo control.

I suggest you use (my) pigpio or servoblaster or RPIO.GPIO for servo pulses. They each use hardware timed pulses. Software timed pulses will be much more subject to jitter (which will shorten the servo's life).

E.g. http://abyz.me.uk/rpi/pigpio/pigs.html#S/SERVO
by joan
Wed Dec 06, 2017 8:54 am
Forum: Advanced users
Topic: Using SMBUS to get something from a weird chip
Replies: 3
Views: 186

Re: Using SMBUS to get something from a weird chip

Have a look at (my) pigpio. It should allow you to do what you want. If the chip is really odd you may have to use the bit bang I2C functions.

http://abyz.me.uk/rpi/pigpio/python.html (search for I2C).
by joan
Mon Dec 04, 2017 9:03 am
Forum: General discussion
Topic: Motor Controller DC Question
Replies: 2
Views: 146

Re: Motor Controller DC Question

The blurb say the solenoid needs 16 watts.

Watts = Volts * Amps.

So if you are powering with 5V you need to supply 16/5, i.e. 3.2 amps. The motor driver you use can only supply 1 amp according to its blurb.
by joan
Sun Dec 03, 2017 8:46 am
Forum: Python
Topic: Cannot Read/Write to i2c bus
Replies: 7
Views: 268

Re: Cannot Read/Write to i2c bus

I don't understand why the I2C write fails with pigpio. You are using bus 1 and the register 0xFA is legal.

Could you try the following code which works with that module.

http://abyz.me.uk/rpi/pigpio/examples.h ... PCA9685_py
by joan
Fri Dec 01, 2017 8:28 pm
Forum: Troubleshooting
Topic: Using pigpio on Windows 10 pc to control ultrasonic sensor
Replies: 2
Views: 109

Re: Using pigpio on Windows 10 pc to control ultrasonic sensor

Try http://abyz.me.uk/rpi/pigpio/examples.h ... er_echo_py

I had a quick look at the posted code and it seemed to assume the Pi was local so results would be instant. The code I linked allows for communication delays by using a different feature of pigpio (alerts).
by joan
Thu Nov 30, 2017 1:41 pm
Forum: General discussion
Topic: Driving Neopixel leds from multiple GPIOs PIn
Replies: 7
Views: 252

Re: Driving Neopixel leds from multiple GPIOs PIn

I don't think that is possible. Those LEDs need very precise timing which is hard to achieve on the Pi. A special technique is used to drive the LEDs which only works on one GPIO (strictly speaking it is one of 4 GPIO, but only one at any one time, and the driver itself only allows GPIO18). APA102 b...
by joan
Thu Nov 30, 2017 10:20 am
Forum: Beginners
Topic: 2 x i2C buses?
Replies: 9
Views: 234

Re: 2 x i2C buses?

Responding to your subject rather than question. You can have kernel supported software I2C buses on any spare Pi GPIO. You need two GPIO per bus. See /boot/overlays/README.
by joan
Tue Nov 28, 2017 10:42 pm
Forum: Automation, sensing and robotics
Topic: Hall Effect Sensor not Reading Fast Enough
Replies: 2
Views: 148

Re: Hall Effect Sensor not Reading Fast Enough

It sounds like a coding problem. I've used Hall effect sensors to measure in excess of 9000 RPM (the sensors were being pulsed in excess of 18000 RPM).

See viewtopic.php?f=37&t=90243

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