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by gordon77
Mon Oct 16, 2017 11:40 am
Forum: Beginners
Topic: Is it possible to connect more than 5V to ground? <-- Warning Nonsense!
Replies: 15
Views: 471

Re: Is it possible to connect more than 5V to ground?

You can power your servos with whatever you need but you will need to interface to the pi gpio which can only work with 3.3v. You need to interface with relays, transistors, optoisolators, mosfets etc.
by gordon77
Sun Oct 15, 2017 3:21 pm
Forum: General discussion
Topic: Why do new forum members not come back?
Replies: 30
Views: 1480

Re: Why do new forum members not come back?

I find the search better than before, and also the search of 'your posts' useful at times :D
by gordon77
Sun Oct 15, 2017 1:56 pm
Forum: General discussion
Topic: Detect an object using Pi Camera
Replies: 1
Views: 77

Re: Detect an object using Pi Camera

Try googling for 'pi and pir sensor' or 'Motion software'

Examples viewtopic.php?f=37&t=119276&p=808746#p808746

viewtopic.php?f=32&t=112332&hilit=Pir#p769779
by gordon77
Fri Oct 13, 2017 3:50 pm
Forum: General discussion
Topic: Switching (and wiring) a relay from Python
Replies: 23
Views: 575

Re: Switching (and wiring) a relay from Python

This looks like it with some more detail...even a circuit diagram of it.

Connect gpio output to S, + to 5v and - to gnd. You maybe lucky and 3.3v on S will be enough.

http://www.techydiy.org/keyes-sr1y-relay-module/
by gordon77
Thu Oct 12, 2017 5:12 pm
Forum: Automation, sensing and robotics
Topic: Auto shut down
Replies: 2
Views: 115

Re: Auto shut down

You could monitor gpio35 for low volts, l assume it still works on recent models/OS.
Clearly it can only see the 5 volts to the Pi so may not see a battery via a boost circuit.
by gordon77
Thu Oct 12, 2017 7:50 am
Forum: General discussion
Topic: Why do new forum members not come back?
Replies: 30
Views: 1480

Why do new forum members not come back?

Have you noticed how a new user will ask a question but then they are never seen on that thread again even when they get answers?

Do they just get the answer and don't bother to acknowledge or have trouble finding the thread they started?
by gordon77
Thu Oct 12, 2017 7:46 am
Forum: General discussion
Topic: How to measure current draw of the RPi
Replies: 31
Views: 1115

Re: How to measure current draw of the RPi

Of all the ideas presented so far, I think the "USB Power Meter" idea is probably going to be the most workable. Having looked at them on Amazon, the thing that is curious is the difference in price between seemingly (more or less) identical devices. For example, the one at the link posted earlier ...
by gordon77
Wed Oct 11, 2017 9:58 am
Forum: Camera board
Topic: Is There a Program w/ GUI That Simply Starts & Stops Recording When You Click a Button?
Replies: 5
Views: 355

Re: Is There a Program w/ GUI That Simply Starts & Stops Recording When You Click a Button?

with a simple GUI... #!/usr/bin/env python3 import picamera import datetime import time import pygame, sys from pygame.locals import * print (" Press Ctrl & C to Quit") global greyColor, dgryColor, whiteColor, greenColor, blackColor, redColor, button_width, button_height greyColor = pygame.Color(128...
by gordon77
Tue Oct 10, 2017 4:33 pm
Forum: Camera board
Topic: Is There a Program w/ GUI That Simply Starts & Stops Recording When You Click a Button?
Replies: 5
Views: 355

Re: Is There a Program w/ GUI That Simply Starts & Stops Recording When You Click a Button?

No GUI but just connect a physical button (switch between pin 26 and gnd).. #!/usr/bin/env python3 import picamera import datetime import time import RPi.GPIO as GPIO GPIO.setmode(GPIO.BCM) GPIO.setwarnings(False) GPIO_SWITCH = 7 # Physical pin 26, switch to GND GPIO.setup(GPIO_SWITCH,GPIO.IN,pull_u...
by gordon77
Mon Oct 09, 2017 8:36 pm
Forum: General discussion
Topic: How to measure current draw of the RPi
Replies: 31
Views: 1115

Re: How to measure current draw of the RPi

You can get meters that plug in the usb varying in price from £6 to much more.. https://www.amazon.co.uk/Centech-USB-Power-Meter/dp/B00DAR4ITE The pi will take the current it needs, is this the smart psu? https://www.maplin.co.uk/p/maplin-24a-quick-charge-20-usb-power-supply-with-intelligent-chargin...
by gordon77
Sat Oct 07, 2017 8:08 am
Forum: Python
Topic: Pi Camera long running time lapse workflow - Help
Replies: 6
Views: 408

Re: Pi Camera long running time lapse workflow - Help

Hopefully what you want #!/usr/bin/env python3 import picamera import os import time from picamera import PiCamera #set file record time in seconds timelapse_time = 60 # first file number filestamp = 0 #write filestamp file if first time if os.path.exists('last.txt') == False: file = open("last.txt"...
by gordon77
Fri Oct 06, 2017 5:19 pm
Forum: Beginners
Topic: Current draw from GPIO pins
Replies: 28
Views: 1011

Re: Current draw from GPIO pins

This site explains a lot! https://www.scribd.com/doc/101830961/GPIO-Pads-Control2 Is " The raspberry-Pi 3V3 supply was designed with a maximum current of ~3mA per GPIO pin. If you load each pin with 16mA the total current is 272mA. The 3V3supply will collapse under that " still True on the latest P...
by gordon77
Fri Oct 06, 2017 4:06 pm
Forum: Beginners
Topic: Current draw from GPIO pins
Replies: 28
Views: 1011

Re: Current draw from GPIO pins

The site does not explain all the restrictons. From a document (can't find it now) I read on this site years ago, the maximum curemt that can be drawn from all the pins at the same time should not exceed 55ma, and the current drawn from any one pin should not exceed 16ma. For the moment ignoring th...
by gordon77
Fri Oct 06, 2017 2:56 pm
Forum: Beginners
Topic: Current draw from GPIO pins
Replies: 28
Views: 1011

Re: Current draw from GPIO pins

This site explains a lot! https://www.scribd.com/doc/101830961/GPIO-Pads-Control2 Is " The raspberry-Pi 3V3 supply was designed with a maximum current of ~3mA per GPIO pin. If you load each pin with 16mA the total current is 272mA. The 3V3supply will collapse under that " still True on the latest P...
by gordon77
Wed Oct 04, 2017 5:37 pm
Forum: Beginners
Topic: Current draw from GPIO pins
Replies: 28
Views: 1011

Re: Current draw from GPIO pins

All I said was 16mA from a GPIO pin and 500mA from the power supply pins. you can draw ... from one or more pins, up to the recommended maximum of 50mA ... through the SOC That would be quite interesting. Do you have a source for that? This seems to be unclear, this link shows the 50mA limit on the...
by gordon77
Sun Oct 01, 2017 4:18 pm
Forum: Camera board
Topic: RaspberryPi Camera for Astrophotography
Replies: 326
Views: 67158

Re: RaspberryPi Camera for Astrophotography

What software are you using ?
by gordon77
Sun Oct 01, 2017 7:40 am
Forum: Camera board
Topic: RaspberryPi Camera for Astrophotography
Replies: 326
Views: 67158

Re: RaspberryPi Camera for Astrophotography

Hi all; I'm a newcomer to this forum. Please forgive me if I make any mistakes. I'm also trying the camera module for astronomy. I have a meade etx 90. I'm having a slow going progress but positive. I was able to get some moon shots that were fairly decent. What I'm using is a pi zero w. I used the...
by gordon77
Sat Sep 30, 2017 9:19 am
Forum: Beginners
Topic: how to determine resistor value for sensor circuit
Replies: 10
Views: 325

Re: how to determine resistor value for sensor circuit

It doesn't appear to give much output as l read it. Between 25mV and 50mV full scale running from 5v?
by gordon77
Fri Sep 29, 2017 4:33 pm
Forum: Beginners
Topic: how to determine resistor value for sensor circuit
Replies: 10
Views: 325

Re: how to determine resistor value for sensor circuit

It would be good to know the details of this sensor. If it needs 5v then it probably won't need any resistor in the supply. The output resistance probably isn't the resistance the supply sees but the output circuit, l assume it has an output you want to connect to the Pi. Make sure any output is int...
by gordon77
Thu Sep 28, 2017 9:49 am
Forum: Python
Topic: Time Function
Replies: 33
Views: 1217

Re: Time Function

Is that the same thing though? I thought the problem being highlighted was when the length of the sleep increased. In your example, the sleep is always 1 second and never increases. EDIT: a lot of this thread is above my head (but interesting nonetheless) so it's perfectly possible that I've misund...
by gordon77
Wed Sep 27, 2017 9:13 am
Forum: Python
Topic: Time Function
Replies: 33
Views: 1217

Re: Time Function

It tells the OS to wait x seconds before continuing with the next instruction. Which is does... as soon as the cpu has finished handling all its other tasks. By the time it trickles back to your Python code it is very likely, and expected, that a few milliseconds have passed. Nothing you can do abo...
by gordon77
Wed Sep 27, 2017 9:05 am
Forum: General discussion
Topic: [SOLVED] Processing video frames
Replies: 12
Views: 495

Re: Processing video frames

Are you trying to split an array into 2 ?

tried ?... https://docs.scipy.org/doc/numpy/refere ... split.html
by gordon77
Tue Sep 26, 2017 5:26 pm
Forum: Python
Topic: Time Function
Replies: 33
Views: 1217

Re: Time Function

Is the timing error due to the processor clock speed? That's the only time reference it has and will vary between boards? The OP hoped for an answer close to One, but got 1.5 Billion instead. That cannot be attributed to clock speed.... I clearly wasn't answering that but the error in the second ti...

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