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by joan
Fri Jul 12, 2019 3:43 pm
Forum: General discussion
Topic: Simple Infra-Red record/playback
Replies: 55
Views: 9017

Re: Simple Infra-Red record/playback

What works? A bit of detail is required.
by joan
Fri Jul 12, 2019 9:14 am
Forum: C/C++
Topic: How to make a command?
Replies: 1
Views: 101

Re: How to make a command?

Start here https://projects.raspberrypi.org/en/pro ... y-pi-using and make sure you understand before continuing.

Then perhaps look at https://projects.raspberrypi.org/en/pro ... thon-sushi
by joan
Thu Jul 11, 2019 10:01 pm
Forum: General discussion
Topic: Raspberry Pi 4 GPIO Direct Register Access
Replies: 2
Views: 256

Re: Raspberry Pi 4 GPIO Direct Register Access

As well as the base address change there is a change to the way GPIO pull-ups and pull-downs are set on the BCM2711.

See https://github.com/RPi-Distro/raspi-gpi ... spi-gpio.c for details.
by joan
Thu Jul 11, 2019 3:27 pm
Forum: Python
Topic: BME280 and pigpio python3.7 extentse Name error
Replies: 4
Views: 119

Re: BME280 and pigpio python3.7 extentse Name error

Works okay for me on Buster. [email protected]:~ $ python3 ./BME280.py h=55.70 p=1002.2 t=24.95 h=55.69 p=1002.2 t=24.94 h=55.65 p=1002.3 t=24.94 h=55.65 p=1002.3 t=24.95 h=55.63 p=1002.2 t=24.94 h=55.64 p=1002.3 t=24.94 h=55.64 p=1002.3 t=24.94 ^C [email protected]:~ $ which python3 /usr/bin/python3 [email protected]:~ $ ...
by joan
Thu Jul 11, 2019 1:34 pm
Forum: Other projects
Topic: Rotary Encoder to Breadboard
Replies: 2
Views: 98

Re: Rotary Encoder to Breadboard

You could connect the devices as you show - it would be pointless though as it would not work. There is a lot of software needed to make a device act as a USB device. Both the pieces of linked kit are just dumb hardware. Plenty of tutorials are available showing how to connect a rotary encoder to th...
by joan
Thu Jul 11, 2019 10:54 am
Forum: Troubleshooting
Topic: pigpio hardware PWM hangs forever in RPi 4
Replies: 3
Views: 95

Re: pigpio hardware PWM hangs forever in RPi 4

I should also mention the following note. At the moment pigpio on the Pi4B is experimental. I am not sure if the DMA channels being used are safe. The Pi4B defaults are primary channel 7, secondary channel 6. If these channels do not work you will have to experiment. You can set the channels used by...
by joan
Thu Jul 11, 2019 10:02 am
Forum: Troubleshooting
Topic: pigpio hardware PWM hangs forever in RPi 4
Replies: 3
Views: 95

Re: pigpio hardware PWM hangs forever in RPi 4

The pre-installed version has not been updated for the Pi4B.

Try pigpiod -v. If it says 68 or less you need to update.

http://abyz.me.uk/rpi/pigpio/download.html

If you install manually it's best to purge the current pre-installation beforehand.

sudo apt purge pigpio
by joan
Thu Jul 11, 2019 7:22 am
Forum: General discussion
Topic: program that counts gpio pin pulses
Replies: 6
Views: 237

Re: program that counts gpio pin pulses

I think the following is what you were using.

http://abyz.me.uk/rpi/pigpio/examples.h ... _status_py
status.jpg
status.jpg (31.28 KiB) Viewed 105 times
by joan
Wed Jul 10, 2019 10:21 pm
Forum: General discussion
Topic: Two servo motors with different periods
Replies: 7
Views: 162

Re: Two servo motors with different periods

I think the minimum clock divider is 2, so that gives a maximum frequency of 250 MHz. However we are talking about PWM so there is no point having a signal which is always on or always off, we need at least one step, that makes the maximum possible PWM frequency 125 MHz. So at 125 MHz we call have P...
by joan
Wed Jul 10, 2019 7:51 pm
Forum: General discussion
Topic: Two servo motors with different periods
Replies: 7
Views: 162

Re: Two servo motors with different periods

The use of the integer million rather than a float of say 100.0 is down to the exposed pigpio socket/pipe interface. http://abyz.me.uk/rpi/pigpio/sif.html in particular command 86 HP. All the parameters are integers. With hind sight I would now have made provision for floating point parameters. Usin...
by joan
Wed Jul 10, 2019 6:19 pm
Forum: General discussion
Topic: Two servo motors with different periods
Replies: 7
Views: 162

Re: Two servo motors with different periods

No, I meant 50 Hz and 75 Hz. The piscope image shows 5 cycles of GPIO 12 in 100 milliseconds and 7.5 cycles of GPIO 13 in 100 milliseconds. The commands I used were: pigs hp 12 50 100000 # 10% dutycycle (10% of 20 ms = 2 ms = 2000 µs) pigs hp 13 75 75000 # 7.5% dutycycle (7.5% of 13.33 ms = 1 ms = 1...
by joan
Tue Jul 09, 2019 5:04 pm
Forum: General discussion
Topic: Two servo motors with different periods
Replies: 7
Views: 162

Re: Two servo motors with different periods

There are such servos. Some servos operate up to 500 Hz.

You can use the PWM peripheral to provide such signals.

Hers is my pigpio doing 50 Hz 2000 µs on GPIO 12 and 75 Hz 1000 µs on GPIO 13.

Code is gpioHardwarePWM in pigpio.c.
Screenshot from 2019-07-09 17-58-37.png
Screenshot from 2019-07-09 17-58-37.png (51.03 KiB) Viewed 152 times
by joan
Tue Jul 09, 2019 4:08 pm
Forum: Beginners
Topic: Intermittent Smbus IOError: [Errno 13] Permission denied
Replies: 2
Views: 67

Re: Intermittent Smbus IOError: [Errno 13] Permission denied

Is a resource being consumed? Running out of memory might result in a confusing error message. Also check the allocation of any file handles. If they are not been opened/closed properly you might run out of handles.
by joan
Tue Jul 09, 2019 11:43 am
Forum: General discussion
Topic: PWM Pulses
Replies: 11
Views: 363

Re: PWM Pulses

Does it matter? Is it stopping you doing what you want to do? The real range is the actual number of steps between off and fully on where there is an actual difference in the pulse output. That is of little interest to most people. They just want to know the way to set the minimum value (0) and the...
by joan
Tue Jul 09, 2019 8:36 am
Forum: General discussion
Topic: PWM Pulses
Replies: 11
Views: 363

Re: PWM Pulses

Does it matter? Is it stopping you doing what you want to do? The real range is the actual number of steps between off and fully on where there is an actual difference in the pulse output. That is of little interest to most people. They just want to know the way to set the minimum value (0) and the ...
by joan
Tue Jul 09, 2019 7:58 am
Forum: Troubleshooting
Topic: Only able to detect 1 out of 4 of my MPU6050s
Replies: 2
Views: 71

Re: Only able to detect 1 out of 4 of my MPU6050s

If the "write signal" was hitting the chip with a hammer then yes, that would stop the chip working.

If you mean something else you need to add detail.

Things like the software used, photos of the wiring etc.
by joan
Mon Jul 08, 2019 8:36 pm
Forum: Raspbian
Topic: BCM2835 library broken after move to RPI4
Replies: 1
Views: 133

Re: BCM2835 library broken after move to RPI4

There are several changes which need to be made by the library maintainer.
  • recognize it's running on a Pi4B.
  • use the new peripheral base address of 0xFE000000.
  • change the GPIO pull-up, pull-down software.
https://www.airspayce.com/mikem/bcm2835/
by joan
Mon Jul 08, 2019 3:17 pm
Forum: Beginners
Topic: DAQC2 plate Modes
Replies: 5
Views: 120

Re: DAQC2 plate Modes

For the sake of those of us (like me) who have no idea what a DAQC2 plate is it would be considerate of you to post links and add an explanation.
by joan
Mon Jul 08, 2019 11:40 am
Forum: General programming discussion
Topic: ESC Direction
Replies: 3
Views: 124

Re: ESC Direction

Not all motors can reverse.

I think we would need details of your motor and your ESC.
by joan
Sun Jul 07, 2019 9:52 am
Forum: Off topic discussion
Topic: OMG - I can't believe I did this
Replies: 11
Views: 648

Re: OMG - I can't believe I did this

Oh dear. I hope you didn't lose anything too precious. :(
by joan
Sat Jul 06, 2019 9:35 pm
Forum: General discussion
Topic: Raspberry Pi 4 Thread - general discussion
Replies: 705
Views: 59854

Re: Raspberry Pi 4 Thread - general discussion

HawaiianPi wrote:
Sat Jul 06, 2019 9:24 pm
Has anyone posted the dimensions of the Pi4 SoC? Tried a google and forum search to no avail, and the mechanical drawing does not show the size of the SoC.
Have a look at https://www.raspberrypi.org/forums/view ... 1&t=244427
by joan
Sat Jul 06, 2019 8:06 am
Forum: Troubleshooting
Topic: UART rpi4 braud rate?
Replies: 14
Views: 291

Re: UART rpi4 braud rate?

What is arm_freq=2150 meant to do?
by joan
Sat Jul 06, 2019 7:18 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: PWM specs
Replies: 3
Views: 145

Re: PWM specs

The pigpio software PWM defaults are 800 Hz with 250 steps (internally mapped to 0-255). If you lower the frequency you get more resolution. If you higher the frequency you get less resolution. E.g. at 8000 Hz there are 25 steps, at 200 Hz there are 1000 steps. The pigpio hardware PWM defaults are 2...
by joan
Fri Jul 05, 2019 12:20 pm
Forum: Beginners
Topic: Which one is a master device between a raspberry pi and arduino
Replies: 5
Views: 215

Re: Which one is a master device between a raspberry pi and arduino

There is a dedicated SPI/BSC SLAVE peripheral to support SPI/I2C as a slave device on the Pi. It is documented from page 160 of the Broadcom spec. http://www.raspberrypi.org/documentation/hardware/raspberrypi/bcm2835/BCM2835-ARM-Peripherals.pdf It doesn't work properly for SPI. Perhaps that has been...

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