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by pcmanbob
Wed Sep 18, 2019 10:57 am
Forum: Beginners
Topic: Multiple DHT22 reading on RPi board
Replies: 1
Views: 28

Re: Multiple DHT22 reading on RPi board

Hi. So a quick google found this page. https://learn.adafruit.com/dht-humidity-sensing-on-raspberry-pi-with-gdocs-logging if your read through the tutorial they explain how to connect a single sensor , but they also say you can add more sensors by just using a different gpio for each DHT22 data pin.
by pcmanbob
Wed Sep 18, 2019 9:51 am
Forum: General discussion
Topic: 'buster': apt-get update > no new updates for days...
Replies: 3
Views: 164

Re: 'buster': apt-get update > no new updates for days...

Just run sudo apt update on one of my pi's running buster lite and got this pi@BusterPi:~ $ sudo apt update Hit:1 http://archive.raspberrypi.org/debian buster InRelease Get:2 http://raspbian.raspberrypi.org/raspbian buster InRelease [15.0 kB] Get:3 http://raspbian.raspberrypi.org/raspbian buster/mai...
by pcmanbob
Wed Sep 18, 2019 9:14 am
Forum: Troubleshooting
Topic: Changing language to English
Replies: 2
Views: 59

Re: Changing language to English

Might help if you post the error message in full so we can see what went wrong.
by pcmanbob
Wed Sep 18, 2019 8:59 am
Forum: Python
Topic: Change in logic in sensor not breaking 'while' loop?
Replies: 3
Views: 96

Re: Change in logic in sensor not breaking 'while' loop?

My first question is what voltage is your sensor working at ? if it has a PNP open collector output then the 2 output states would be, output off = 0V to pi gpio, output on= supply voltage to pi gpio. I suggest you do some testing with you sensor and a digital voltmeter to determine what the output ...
by pcmanbob
Wed Sep 18, 2019 8:40 am
Forum: Troubleshooting
Topic: rc.local won't load images as part of python script
Replies: 2
Views: 39

Re: rc.local won't load images as part of python script

rc.local runs in a different environment to your command line , so in your program you have to inclue the full directory path to any file ( including image files ) that you want to open. So this needs changing images/backup_icon.png to include the full path from root /..../..../images/backup_icon.pn...
by pcmanbob
Wed Sep 18, 2019 8:34 am
Forum: General discussion
Topic: Making button execute script more than once
Replies: 1
Views: 62

Re: Making button execute script more than once

To make a program run repeatedly you need to a a loop for the part of the program that needs to run continuously. So in your program it needs to loop the part of the code that waits for the falling edge and the code that switches the display on or off. like this import RPi.GPIO as GPIO import subpro...
by pcmanbob
Tue Sep 17, 2019 7:35 pm
Forum: Troubleshooting
Topic: The mystery of 3 dead pi4s
Replies: 14
Views: 396

Re: The mystery of 3 dead pi4s

I would suggest you use the new pi4B official power supply , which is now 3A as you have an external drive connected.

https://www.raspberrypi.org/products/ty ... er-supply/

You might also try not using the full-board radiator as that seems to be the only difference between you pi3 and pi4 setup.
by pcmanbob
Tue Sep 17, 2019 7:23 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: ADXL345 SPI interfacing on Raspberry pi
Replies: 1
Views: 29

Re: ADXL345 SPI interfacing on Raspberry pi

Hi.

If you can change the I2C address of the second ADXL345 accelerometer, you can connect that to the same I2C pins and then just use the address for each ADXL345 accelerometer to access both of them via I2C
by pcmanbob
Tue Sep 17, 2019 7:13 pm
Forum: Troubleshooting
Topic: RPI 4B not booting
Replies: 2
Views: 64

Re: RPI 4B not booting

boot it only makes the green led flicker alot randomly, while the red led is always on. Im booting headless* Hi. From your description I would say your pi is booting , red LED on good, green LED flashing randomly good. which OS have you installed ? So what were you expecting ? how are you intending...
by pcmanbob
Tue Sep 17, 2019 7:07 pm
Forum: Troubleshooting
Topic: The mystery of 3 dead pi4s
Replies: 14
Views: 396

Re: The mystery of 3 dead pi4s

HI. As we don't seem to have had droves of people here saying there pi4B only lasted 24hr or less, it would suggest its something you have connected to your pi that's causing this repeatable failure. So first question would be what's this " with a full-board radiator " and was it designed for the pi...
by pcmanbob
Tue Sep 17, 2019 6:39 pm
Forum: Beginners
Topic: GPIO pin to trigger 555 astable circuit
Replies: 4
Views: 90

Re: GPIO pin to trigger 555 astable circuit

Hi. If you really must use a 555 timer to make your LED flash then this will allow you pi gpio to switch it on and off. https://i.imgur.com/aIMTjzk.jpg A simpler answer is to use a flashing LED ( 5mm, red ,flashing ) https://www.ebay.co.uk/itm/Special-LEDs-3mm-5mm-Flashing-Flickering-Bi-Colour-Tri-C...
by pcmanbob
Tue Sep 17, 2019 3:24 pm
Forum: Troubleshooting
Topic: RPi 4 has stopped booting, red light constantly on
Replies: 11
Views: 267

Re: RPi 4 has stopped booting, red light constantly on

So I assuming you unzipped the download file and copied the 3 files on to the SD card which you had formatted fat32. When you tried booting the pi from this SD card you have to wait for the Green LED to flash quickly, if it does not and you are sure your SD card has been prepared correctly then I wo...
by pcmanbob
Tue Sep 17, 2019 1:51 pm
Forum: Automation, sensing and robotics
Topic: How Many Sensors/Motors Can a Raspberry Pi 3 Handle at Once?
Replies: 6
Views: 150

Re: How Many Sensors/Motors Can a Raspberry Pi 3 Handle at Once?

You are only taking about sending high or low signals to the H-bridge so a mA or 2 at most per gpio pin, same goes for the servo pwm signal for control , you should be able to power a small servo like the SG90, from the 5v gpio pin , probably 200mA max, range sensor assuming HC-SR04 15mA per sensor....
by pcmanbob
Tue Sep 17, 2019 12:38 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Spidev not working
Replies: 14
Views: 240

Re: Spidev not working

Well in the image you posted its clear you are using the command python which is python 2, if you want to run python 3 then you need to use python3 . Run the install command that joan posted and I repeated and it will install for both python 2 and python 3 The install command you posted is not corre...
by pcmanbob
Tue Sep 17, 2019 11:38 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Spidev not working
Replies: 14
Views: 240

Re: Spidev not working

So did you install spidev for python 2 or python 3 ?

you are running your program using python which is python 2

As joan suggested try the install again this time for both.

Code: Select all

sudo apt update
sudo apt install python-spidev python3-spidev
by pcmanbob
Tue Sep 17, 2019 11:34 am
Forum: Troubleshooting
Topic: RPi 4 has stopped booting, red light constantly on
Replies: 11
Views: 267

Re: RPi 4 has stopped booting, red light constantly on

If you don't get the 4 flashes with NO SD card in your pi when trying to boot. then you need to try the EEPROM recovery as drgeoff suggested. Remember you need to format the SD card you want to use for this as fat32 , so if you are using a large SD card you may have to use special formatting softwar...
by pcmanbob
Tue Sep 17, 2019 7:58 am
Forum: Beginners
Topic: Computer monitor & Raspberry Pi 4B
Replies: 5
Views: 150

Re: Computer monitor & Raspberry Pi 4B

So yes it will work, I use a DVI to HDMI cable for all my pi's when connecting to my monitor , I just have to use a micro HDMI to HDMI adapter for the pi4. so a quick google search came up with these. https://www.raspberrypi.org/products/micro-hdmi-to-standard-hdmi-a-cable/ https://shop.pimoroni.com...
by pcmanbob
Tue Sep 17, 2019 7:38 am
Forum: Automation, sensing and robotics
Topic: How Many Sensors/Motors Can a Raspberry Pi 3 Handle at Once?
Replies: 6
Views: 150

Re: How Many Sensors/Motors Can a Raspberry Pi 3 Handle at Once?

Hi.

You can work this out for yourself,

The pi has 26 possible gpio pins for use ,

you just need to add up how many gpio pins you need for each device

H-bridge = 6
range sensor = 2 for 3 sensors = 6
servo = 1

total 13

so you still have 13 gpio left

its as simple as that.
by pcmanbob
Tue Sep 17, 2019 7:29 am
Forum: Troubleshooting
Topic: RPi 4 has stopped booting, red light constantly on
Replies: 11
Views: 267

Re: RPi 4 has stopped booting, red light constantly on

What happens if you boot your pi with just the power supply connected and no SD card inserted.

do you got the 4 flashes that repeat ?
by pcmanbob
Mon Sep 16, 2019 6:47 pm
Forum: Beginners
Topic: gpio button works on pi3 but not pi4... but LEDs on pi4 works?.....
Replies: 14
Views: 288

Re: gpio button works on pi3 but not pi4... but LEDs on pi4 works?.....

I ran: $ pip3 install --upgrade --pre rpi.gpio and everything works as normal now!! Thanks everyone for the help!! If this fixed your problem then it suggests you have never run an update on buster since flashing you SD card. There have been a lot of updates for buster and the pi 4 , so I would sug...
by pcmanbob
Mon Sep 16, 2019 5:16 pm
Forum: Troubleshooting
Topic: RPi 4 has stopped booting, red light constantly on
Replies: 11
Views: 267

Re: RPi 4 has stopped booting, red light constantly on

Hi. If your green LED is flashing then your pi has 3.3v so it's unlikely to have been damage by your power supply. But if you power supply is under powered , have you seen the undervolt symbol on the screen? , You might have a corrupted SD card so I would suggest you try a fresh install of raspbian ...
by pcmanbob
Mon Sep 16, 2019 1:52 pm
Forum: Media centres
Topic: No signal to Pi 3+ with TV aerial splitter but ok with aerial cable direct?
Replies: 10
Views: 138

Re: No signal to Pi 3+ with TV aerial splitter but ok with aerial cable direct?

Surely the IN connector goes to the TV? Leaving one of the other connectors for the incoming aerial cable and the other for the Pi? Signal from the antenna goes to IN and then splits into the two OUTs for the TV and Pi... ^ What he said........ IN to splitter out to TV, hence aerial to IN TV's to O...
by pcmanbob
Mon Sep 16, 2019 1:38 pm
Forum: Media centres
Topic: No signal to Pi 3+ with TV aerial splitter but ok with aerial cable direct?
Replies: 10
Views: 138

Re: No signal to Pi 3+ with TV aerial splitter but ok with aerial cable direct?

As I said aerial needs connecting to the one marked IN.
by pcmanbob
Mon Sep 16, 2019 1:15 pm
Forum: Media centres
Topic: No signal to Pi 3+ with TV aerial splitter but ok with aerial cable direct?
Replies: 10
Views: 138

Re: No signal to Pi 3+ with TV aerial splitter but ok with aerial cable direct?

Are you sure you have a splitter connected correctly, they are often market showing which port is input ( aerial ) , incorrectly connecting them may lead to the signal not being passed through. Looking at your image I can't see the markings but comparing it with this image https://i.imgur.com/fDZmES...
by pcmanbob
Mon Sep 16, 2019 1:05 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Spidev not working
Replies: 14
Views: 240

Re: Spidev not working

May be this tutorial and the associated github page will help.

https://pimylifeup.com/raspberry-pi-rfid-rc522/

https://github.com/pimylifeup/MFRC522-python

amazing what a google search will find.

There are lots more pages on the subject I just picked one at random.

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