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by geoffr
Mon Jul 10, 2017 12:39 am
Forum: General discussion
Topic: Pi Zero W availability
Replies: 110
Views: 12205

Re: Pi Zero W availability

The bare Zero W is still in stock in singles at modmypi , pimoroni and thepihut [clickable links] I think one problem is the number of Pi Zeros that people buy. If I just look at my own collection, I have 2 Model Bs (with the 26 pin header), a Pi 2, a Pi3, and about 10 Pi Zeros. The zero is so chea...
by geoffr
Thu Jun 15, 2017 12:32 am
Forum: General discussion
Topic: Battery elements for portable pi
Replies: 6
Views: 938

Re: Battery elements for portable pi

One way to improve battery runtime is of course to reduce power draw. That raises the question of whether you could get away with a Pi Zero rather than a Pi 3? If the Pi Zero has enough grunt for your application, that could be a big power saving, and depending on the current draw of your other comp...
by geoffr
Wed Apr 26, 2017 3:25 am
Forum: General discussion
Topic: Real Time Clock (RTC) help in finding one.
Replies: 18
Views: 1797

Re: Real Time Clock (RTC) help in finding one.

Nice set up. How accurate has ur clock been? Thanks. I haven't paid a lot of attention to it, as I am happy if it is vaguely close to the real time. As soon as it gets network connectivity, it will sync to NTP. My main concern is in case it reboots without a network - I don't want it to start water...
by geoffr
Wed Apr 26, 2017 2:34 am
Forum: General discussion
Topic: Real Time Clock (RTC) help in finding one.
Replies: 18
Views: 1797

Re: Real Time Clock (RTC) help in finding one.

I guess it depends on the amount of effort you are prepared to go to in order to attach your RTC. All the RTCs I can think of use the I2C bus to attach. That dictates the GPIO pins they use. You could attach one to to I2C bus 0, but that bus is supposed to be reserved for HATs. Another approach is t...
by geoffr
Wed Apr 19, 2017 12:29 pm
Forum: General discussion
Topic: Pi3 Bluetooth and WiFi coexistence
Replies: 1
Views: 506

Pi3 Bluetooth and WiFi coexistence

I am running into problems with my Pi 3 which seem to be an issue of Bluetooth and WiFi coexistence. Whenever I have both Bluetooth and WiFi enabled, I have problems with my Bluetooth keyboard - either keypresses are missed, or they continuously repeat. As soon as I turn off WiFi, the problem goes a...
by geoffr
Tue Apr 11, 2017 6:15 am
Forum: General discussion
Topic: Turning on Zero W every hour
Replies: 46
Views: 9187

Re: Turning on Zero W every hour

Zero in halt/sleep - 30ma is a lot. Low power timers like the TI TLP range are nano amp. Something a bit more accurate would be nice, so an RTC. That does require a bit of code to set the next wake up time. Any RTC with periodic wakeups? Zero's can also handle low voltage so direct LiPo power on 5V...
by geoffr
Tue Apr 11, 2017 3:55 am
Forum: General discussion
Topic: Turning on Zero W every hour
Replies: 46
Views: 9187

Re: Turning on Zero W every hour

I'm trying to build a battery powered system with an e-paper display. It would wake up every hour, make an HTTP request (e.g., to a twitter feed), update the display and shut down. Everything seems to be pretty straightforward, except for the waking up every hour part. I'd like to avoid using bulky...
by geoffr
Sun Apr 09, 2017 11:29 pm
Forum: Raspbian
Topic: Apple wireless keyboard on RPi 3
Replies: 1
Views: 1809

Apple wireless keyboard on RPi 3

I have for a while been using an Apple wireless keyboard and magic mouse with a RPI 3, doing the pairing of both devices through the GUI. A recent update seems to have affected the wireless keyboard. - I am now struggling to get it to pair via the GUI, and if it does, it doesn't function properly - ...
by geoffr
Wed Apr 05, 2017 4:45 am
Forum: General discussion
Topic: Pi Zero W - setting up SSID for headless
Replies: 3
Views: 2287

Re: Pi Zero W - setting up SSID for headless

You mean like putting a wpa_supplicant file in the /boot partition? A feature that already exists... Yup. Along with the "ssh" file, create another file called "wpa_supplicant.conf" with the following information in it. network={ ssid="your-router-SSID" psk="your-WPA/WPA2-passphrase" } When Raspbia...
by geoffr
Tue Apr 04, 2017 12:24 am
Forum: General discussion
Topic: Pi Zero W - setting up SSID for headless
Replies: 3
Views: 2287

Pi Zero W - setting up SSID for headless

Firstly, I wanted to comment that the Pi zero W addresses probably one of the biggest things people have been requesting of the Pi Zero. Well done to the Foundation! One of the challenges is that for someone setting up a headless Pi with a WiFi interface is that it can be challenging to set up the S...
by geoffr
Sat Apr 01, 2017 7:30 am
Forum: Advanced users
Topic: Problems with Apple bluetooth keyboard and mouse
Replies: 1
Views: 440

Problems with Apple bluetooth keyboard and mouse

I have been using an Apple Bluetooth keyboard and Magic Mouse with a Pi 3b for a while. A recent update seems however to have started causing problems. What is especially noticeable is that the keyboard often does not connect. When it does connect, it often doesn't register keypresses and then on on...
by geoffr
Wed Mar 08, 2017 11:01 am
Forum: General discussion
Topic: maximum practical length of ethernet (UTP) ?
Replies: 15
Views: 2283

Re: maximum practical length of ethernet (UTP) ?

I know the standard says 100 meters is the maximum length over the standard UTP cable, for both 10BaseT and 100BaseT. http://www.cisco.com/c/en/us/support/docs/routers/10000-series-routers/46792-ethbase.html I've also heard anecdotal evidence that people have successfully run IP cameras using much ...
by geoffr
Sun Mar 05, 2017 10:26 pm
Forum: General discussion
Topic: Wlan Dongle for Raspberry Pi2 B - Which one should I use?
Replies: 9
Views: 1375

Re: Wlan Dongle for Raspberry Pi2 B - Which one should I use

Hey guys! I have found my old Raspberry Pi 2 B and wanted to use it as a mediacenter. I installed OSMC and got it working on my TV without problems. Sadly my Wlan-Dongle which I am using for other devices is not supported. Which one should I buy if I want to stream full HD videos? There is a list w...
by geoffr
Sun Mar 05, 2017 10:19 pm
Forum: General discussion
Topic: Raspberry Pi as a bicycle computer
Replies: 8
Views: 4143

Re: Raspberry Pi as a bicycle computer

With the speed that a bike wheel runs at it may not be a switch (I'm not sure they'd react quickly enough). It's probably using a hall effect sensor. I got a reading of 52 miles per hour when I tripped the 40mph speed camera on the way into Brighton off Ditchling Beacon (closed roads for the BHF Lo...
by geoffr
Wed Mar 01, 2017 4:02 am
Forum: General discussion
Topic: PI Zero W info
Replies: 80
Views: 11590

Re: PI Zero W - why no info on this site?

A zero with WiFi, c'mon you guys are taking the mick (is it April 1st?) It makes a lot of sense; add '$1 of WiFi/BT and jack the price up by $5'. Whatever the actual cost and profit, let's hope it's enough to make the Zero W manufacturable in quantity. Looking forward to the W+ which has an antenna...
by geoffr
Thu Jan 12, 2017 3:05 am
Forum: General discussion
Topic: Raspberrypi 0
Replies: 22
Views: 2830

Re: Raspberrypi 0

RaTTuS wrote:it will need 5V @ <1000mA [I think it will run on <500mA]
I've generally seen a Zero with USB Wifi using 200mA or less. That is with the CPU not doing a whole lot of work, however. I expect a 500mA supply should be fine for many purposes.
by geoffr
Fri Dec 16, 2016 3:04 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Communication with ATTiny85
Replies: 2
Views: 1211

Re: Communication with ATTiny85

I did a small test with I2C on an ATTiny85 some years ago. Some tips: 1. Lower the I2C speed. 2. Perform as little as possible in the I2C callback on the Tiny. I sampled the sensor in the main loop and stored it, so the callback only sent a value. 3. On the Pi side, catch any errors and handle them...
by geoffr
Fri Dec 16, 2016 12:41 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Communication with ATTiny85
Replies: 2
Views: 1211

Communication with ATTiny85

I am busy tinkering around at the moment with using an ATTiny85 microcontroller to provide an analogue input to a Pi (the ultimate goal is to built a water level sensor for my rainwater tanks using a differential pressure sensor). I am currently using I2C, but have been running into the issue that t...
by geoffr
Fri Dec 16, 2016 12:30 am
Forum: General discussion
Topic: Gigabit Ethernet at this stage?
Replies: 157
Views: 20275

Re: Gigabit Ethernet at this stage?

Whatever happens to Pi's in the future, I suspect the price point will remain inviolate. This is a very important point. It is the price point of the RPi which has driven its success, and which makes it possible to use a Pi for so many things. Going back to its main goal - education - price is key ...
by geoffr
Sun Nov 20, 2016 10:47 pm
Forum: General discussion
Topic: Any reason not to use a USB power bank as an UPS?
Replies: 17
Views: 20863

Re: Any reason not to use a USB power bank as an UPS?

Don't know how well it would work but quite a few people use capacitors on dashcams so there may be a method for those little glitches that shut down your Pi. I'm starting to look at this issue for the irrigation controller I am building using a Pi Zero. I don't really care about losing 24VAC power...
by geoffr
Thu Oct 20, 2016 9:37 am
Forum: Automation, sensing and robotics
Topic: EMI suppression for inductive AC loads
Replies: 7
Views: 1516

Re: EMI suppression for inductive AC loads

Although my commercial sprinkler controller uses triacs, it has a MOV across each one. Its part number is S10K30 and it has a 47V breakdown voltage. They are available from DigiKey . You could try a 0.1uF capacitor across the load, without any series resistor. You do have the DC power to the Pi sep...
by geoffr
Thu Oct 20, 2016 9:31 am
Forum: Automation, sensing and robotics
Topic: EMI suppression for inductive AC loads
Replies: 7
Views: 1516

Re: EMI suppression for inductive AC loads

If I were trying to solve this problem at work I'd probably focus on isolation between the electronics and the loads, rather than trying to silence the solenoids. Solenoids are always going to be noisy; MOVs will help but you'll never get rid of the transients completely. .... My initial tests usin...
by geoffr
Mon Oct 17, 2016 7:38 pm
Forum: Automation, sensing and robotics
Topic: EMI suppression for inductive AC loads
Replies: 7
Views: 1516

Re: EMI suppression for inductive AC loads

Although my commercial sprinkler controller uses triacs, it has a MOV across each one. Its part number is S10K30 and it has a 47V breakdown voltage. They are available from DigiKey . You could try a 0.1uF capacitor across the load, without any series resistor. You do have the DC power to the Pi sep...
by geoffr
Fri Oct 14, 2016 4:12 am
Forum: Automation, sensing and robotics
Topic: EMI suppression for inductive AC loads
Replies: 7
Views: 1516

EMI suppression for inductive AC loads

One of the interesting challenges I am running into with building an irrigation controller is the EMI generated as a result of switching the solenoid valves. There are really two sets of inductive loads in the project: the relays which switch the AC circuits (here I have flyback diodes integrated in...
by geoffr
Sat Sep 10, 2016 10:44 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: A different way to mount a Pi Zero
Replies: 1
Views: 686

A different way to mount a Pi Zero

A project I have been working, rather slowly, is an irrigation controller, which uses a Pi Zero as the brains. I am using a MCP23017 GPIO expander for my outputs, with ULN2803A Darlington transistor arrays providing the conversion from 3.3V to 5V (and allowing me to get enough current to drive my re...

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