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by joan
Wed Oct 23, 2019 3:05 pm
Forum: Compute Module
Topic: computer module 3+, i need to use SPI1
Replies: 2
Views: 131

Re: computer module 3+, i need to use SPI1

By experiment modes 1 and 3 do not appear to work on the auxiliary SPI. See warning in

http://abyz.me.uk/rpi/pigpio/pigs.html#SPIO
by joan
Wed Oct 23, 2019 9:04 am
Forum: General discussion
Topic: Need 50% wave, not PWM
Replies: 9
Views: 239

Re: Need 50% wave, not PWM

Perhaps something else is using GPIO 4? 1-wire bus?
by joan
Wed Oct 23, 2019 8:28 am
Forum: General discussion
Topic: Need 50% wave, not PWM
Replies: 9
Views: 239

Re: Need 50% wave, not PWM

The link I gave lists the permissible GPIO. Please be aware that GPIO 6 does not appear to work at that frequency on the Pi4B.

If you want to use GPIO 18 I suggest you use hardware_PWM instead.

http://abyz.me.uk/rpi/pigpio/python.html#hardware_PWM
by joan
Sun Oct 20, 2019 7:09 pm
Forum: Beginners
Topic: How do I know what to install for a program?
Replies: 4
Views: 125

Re: How do I know what to install for a program?

You install the package you want to use, deluge I guess. Anything it needs will be automatically installed.
by joan
Sun Oct 20, 2019 12:30 pm
Forum: Off topic discussion
Topic: Can't message anyone
Replies: 7
Views: 278

Re: Can't message anyone

The report post button gives a comment field. Ask your question in the comments field.

To my knowledge only one user has ever had his user name changed. Others just totally stop using one account and start using another.
by joan
Sun Oct 20, 2019 11:30 am
Forum: Off topic discussion
Topic: Can't message anyone
Replies: 7
Views: 278

Re: Can't message anyone

Private Messages have been turned off for a variety of reasons.

Use the report post button (flag, top right of each post) to report your own post for moderator attention.
by joan
Sun Oct 20, 2019 7:36 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Very Innacurate MCP 3008 Readings
Replies: 14
Views: 377

Re: Very Innacurate MCP 3008 Readings

No. It's likely a sign of faulty wiring.

Schematics are pretty and can be useful but are not a substitute for clear photos which show the actual wiring.
by joan
Sat Oct 19, 2019 5:19 pm
Forum: Beginners
Topic: Need guidance on very specific LED use-case
Replies: 9
Views: 467

Re: Need guidance on very specific LED use-case

I can't make out which GPIO you have connected to the data and clock lines. Have you also connected a ground pin to the LED strip ground?
by joan
Sat Oct 19, 2019 11:37 am
Forum: Troubleshooting
Topic: 5V pins output 3.3V and 3.3V outputs 2.5V
Replies: 10
Views: 247

Re: 5V pins output 3.3V and 3.3V outputs 2.5V

Does the Pi boot?

If it does your meter needs a fresh battery or you are not measuring correctly.
by joan
Sat Oct 19, 2019 3:18 am
Forum: Advanced users
Topic: Highly precise timing on rpi
Replies: 3
Views: 264

Re: Highly precise timing on rpi

Look at pigpio waves for transmission from the Pi. You could try pigpio sampling at 1 MHz for reception but it's doubtful that would work. Perhaps use SPI to capture the incoming data (i.e. oversample at perhaps 4 MHz, ignore the clock, read many times the number of bytes you expect to receive and p...
by joan
Fri Oct 18, 2019 11:36 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Manchester Encode/Decode [obsolete]
Replies: 8
Views: 3969

Re: Manchester Encode/Decode

This is an old thread.

pigpio has the hooks needed to encode/decode Manchester code for signals with bit transitions in the >microsecond range. What do you need to do?
by joan
Thu Oct 17, 2019 9:21 pm
Forum: Automation, sensing and robotics
Topic: pigpio capabilities?
Replies: 9
Views: 517

Re: pigpio capabilities?

Thanks for the info. It does make sense about the voltage drop but it's not something I would ever have thought of. I'll bear that in mind as I expect I'll see similar problems in the future. Watching that robot arm spinning about reminded me of the considerably larger Foxhunter radar which also mov...
by joan
Thu Oct 17, 2019 7:51 pm
Forum: Automation, sensing and robotics
Topic: pigpio capabilities?
Replies: 9
Views: 517

Re: pigpio capabilities?

Just to be clear, are you saying the servo jitter mentioned in your earlier post was being caused by a ground problem?

That is an impressive gripper you have there. I'd have thought the code to pick and drop would be a lot more sophisticated! :oops:
by joan
Wed Oct 16, 2019 4:40 pm
Forum: Troubleshooting
Topic: I2C Start condition bug
Replies: 2
Views: 57

Re: I2C Start condition bug

Moot. The Linux driver is SMBus based which does not allow infinite clock stretching.
by joan
Wed Oct 16, 2019 10:20 am
Forum: Troubleshooting
Topic: GPIOZero - Repeatedly calling detach casues servo to stop.
Replies: 10
Views: 226

Re: GPIOZero - Repeatedly calling detach casues servo to stop.

My bad. It does work with the correct invocation on the command line. export GPIOZERO_PIN_FACTORY=pigpio python or GPIOZERO_PIN_FACTORY=pigpio python NOT GPIOZERO_PIN_FACTORY=pigpio python There is the added bonus that detach seems to work properly with the pigpio backend (I stopped testing after 40...
by joan
Wed Oct 16, 2019 9:14 am
Forum: Troubleshooting
Topic: GPIOZero - Repeatedly calling detach casues servo to stop.
Replies: 10
Views: 226

Re: GPIOZero - Repeatedly calling detach casues servo to stop.

Strange. Perhaps we are using the wrong invocation. I just checked by looking at the debug messages coming out of the pigpio daemon. The backend wasn't being used when I did GPIOZERO_PIN_FACTORY=pigpio before invoking Python and importing gpiozero. pigpio provides two types of PWM. That used by the ...
by joan
Tue Oct 15, 2019 12:50 pm
Forum: Beginners
Topic: Problem with pin 7 in led light
Replies: 3
Views: 88

Re: Problem with pin 7 in led light

The 1-wire bus is used for devices which use the 1-wire (Dallas) protocol. The commonest device I know of is the Dallas DS18B20 temperature sensor.

See https://en.wikipedia.org/wiki/1-Wire
by joan
Tue Oct 15, 2019 8:45 am
Forum: Beginners
Topic: Problem with pin 7 in led light
Replies: 3
Views: 88

Re: Problem with pin 7 in led light

If you mean physical pin 7 then that is connected to GPIO 4. GPIO 4 is used by the 1-wire bus.

Check that the 1-wire bus is disabled in /boot/config.txt
by joan
Mon Oct 14, 2019 8:01 pm
Forum: Troubleshooting
Topic: Hardware clock 2 not working on some frequencies
Replies: 7
Views: 332

Re: Hardware clock 2 not working on some frequencies

Clock 2 (GPIO 6) seems to stop working completely at 185021 Hz and above on the Pi4B.

Until we get sight of the peripheral datasheet there's not much to be done.
by joan
Mon Oct 14, 2019 3:21 pm
Forum: Troubleshooting
Topic: Hardware clock 2 not working on some frequencies
Replies: 7
Views: 332

Re: Hardware clock 2 not working on some frequencies

I might try on the Pi4B with a logic analyser attached. It only samples at 24 MHz but that should be enough to see the problem.

The Pi4B peripheral datasheet should be available before year end. That might show a reason.
by joan
Mon Oct 14, 2019 3:16 pm
Forum: Troubleshooting
Topic: GPIOZero - Repeatedly calling detach casues servo to stop.
Replies: 10
Views: 226

Re: GPIOZero - Repeatedly calling detach casues servo to stop.

I am surprised you are getting noticeable jitter from the pigpio backend. pigpio servo pulses are hardware timed.
by joan
Sun Oct 13, 2019 7:39 pm
Forum: Beginners
Topic: Regarding the current measurement
Replies: 23
Views: 669

Re: Regarding the current measurement

There is no way to measure the SoC current consumption in software.

You will have to design and build your own solution using the methods outlined by mahjongg.
by joan
Sun Oct 13, 2019 7:14 pm
Forum: Troubleshooting
Topic: Hardware clock 2 not working on some frequencies
Replies: 7
Views: 332

Re: Hardware clock 2 not working on some frequencies

The code doesn't really distinguish between the clocks other than setting the correct mode for the GPIO. I can think of no reason why clock 0 should operate differently from clock 2.

Does the same happen on earlier Pis? If not perhaps this is a change in the Pi4B.

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