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by MarkDH102
Mon Jun 17, 2019 5:08 pm
Forum: Off topic discussion
Topic: Communicating with a RS232 generic ublox GPS
Replies: 0
Views: 49

Communicating with a RS232 generic ublox GPS

I have a 3.3V RS232 Ublox chipset GPS connected to my Pi via the serial lines. No problems. Works well. However, I wanted to disable some of the NMEA messages and to do this I needed to use ublox u-center software. This runs on Windows. I don't have a USB-Serial adapter that works on 3.3V. But I did...
by MarkDH102
Wed Jun 05, 2019 6:23 am
Forum: Python
Topic: Why wasn't this error trapped?
Replies: 2
Views: 169

Re: Why wasn't this error trapped?

Ok, thanks for that link. A bit of heavy reading first thing in the morning!
As yet, I still haven't been able to figure out how to get around the issue, but I'm sure that with a longer read, it will come to me...
by MarkDH102
Tue Jun 04, 2019 4:26 pm
Forum: Python
Topic: Why wasn't this error trapped?
Replies: 2
Views: 169

Why wasn't this error trapped?

I have some code that has been running ok for a number of years now but this morning it failed. It is invoked as a callback in tkinter. Python3. So it appeared to fail at the "name resolution" in the initial allocation of "server", but why didn't my try..except..finally catch it properly? Function a...
by MarkDH102
Sun Jun 02, 2019 6:14 am
Forum: AIY Projects
Topic: Illegal Instruction on import of google assistant
Replies: 2
Views: 135

Re: Illegal Instruction on import of google assistant

Ah, ok, great :-( . Thanks for that.
So it would appear I can't run my code on the Pi Zero W at all then. And I put everything in a nice little box too. (Only the zero form factor will fit in there).
Oh well, you live and learn.
by MarkDH102
Sat Jun 01, 2019 2:53 pm
Forum: AIY Projects
Topic: Illegal Instruction on import of google assistant
Replies: 2
Views: 135

Illegal Instruction on import of google assistant

I had a fully working system (AIY Voice) on my Pi2B V1.1 with a Logitech USB microphone and an Edimax WiFi dongle attached. I updated / upgraded the card and it all still worked. I then put the card into a Pi0W and now I get "Illegal Instruction" when I try to do : from google.assistant.library.even...
by MarkDH102
Thu May 09, 2019 6:31 am
Forum: Beginners
Topic: Sending e-mail notifications when temperature is over 8°C
Replies: 1
Views: 76

Re: Sending e-mail notifications when temperature is over 8°C

This is what I use to email temperature alarms from my sensor. import smtplib from email.mime.text import MIMEText from email.mime.multipart import MIMEMultipart from email.mime.image import MIMEImage import signal class TimeoutException(Exception) : pass def _timeout(signum, frame) : raise TimeoutE...
by MarkDH102
Tue Apr 30, 2019 6:13 am
Forum: General discussion
Topic: Problem with range of 433 Mhz receiver
Replies: 8
Views: 343

Re: Problem with range of 433 Mhz receiver

Signal levels are so weak, and the "modulation method" so simple, that even if 0.001% of a PI generated signal will overwhelm the receiver if its too close. It will simply "see" the 433MHz signal all the time. A "better receiver", (meaning more sensitive) will therefore not help. That's very intere...
by MarkDH102
Mon Apr 29, 2019 6:20 am
Forum: Beginners
Topic: raspberry pi as a server watchdog
Replies: 7
Views: 310

Re: raspberry pi as a server watchdog

The Raspberry Pi is just as likely to go down as your server in my opinion. Too much underlying code. I would look at using an ESP8266 or a similar Arduino solution. I have ESP8266 and Arduino code that has been running for a couple of years with no intervention ( and the internal watchdog has never...
by MarkDH102
Sat Apr 27, 2019 6:15 am
Forum: Troubleshooting
Topic: DHT22 Accuraty.
Replies: 2
Views: 121

Re: DHT22 Accuraty.

I too use the BME280.
I used to use the DHT22 but running the 2 in parallel showed the BME280 seemed to be more accurate.
My DHT22 were always reading about 20% over the correct level - but were consistent...
by MarkDH102
Sat Apr 27, 2019 6:07 am
Forum: General discussion
Topic: weight scales: Do-able with Raspberry?
Replies: 5
Views: 334

Re: weight scales: Do-able with Raspberry?

I have successfully used a Wii Fit board (Bluetooth to the Pi). I control power to the Wii Fit via a relay (which required dismantling the Wii Fit (very easy) ). I use it as a personal weigher. The other thing I had to do was attach a 1000uF capacitor across the 5V rail of my Pi zero W as when the W...
by MarkDH102
Tue Apr 09, 2019 6:25 am
Forum: General discussion
Topic: GIVE YOUR RASPBERRY PI SD CARD A BREAK: LOG TO RAM
Replies: 19
Views: 2330

Re: GIVE YOUR RASPBERRY PI SD CARD A BREAK: LOG TO RAM

In all of my data logging pi's, I log the data to RAM for 24 hours and then commit it to SD card (and email a copy) at midnight. Other than that my applications do not write to the SD card. These Pi's are also UPS protected... But I have had a couple of SD cards go write only on me (and only after a...
by MarkDH102
Fri Mar 29, 2019 8:07 am
Forum: Troubleshooting
Topic: VNC Interface won't stay enabled
Replies: 15
Views: 669

Re: VNC Interface won't stay enabled

No, I'm using the standard REALVNC. 3 * Pi0w are all exhibiting the same problem. All my pi's - Stretch - are updated once a month. I can't say when the problem started, as I had a power cut, all my pi's rebooted. Then found I couldn't connect. I only have a screen plugged into one of them and after...
by MarkDH102
Fri Mar 29, 2019 7:15 am
Forum: Python
Topic: RF Communication with Python (Send Only)
Replies: 11
Views: 2128

Re: RF Communication with Python (Send Only)

I actually use a homebrew ATMEGA328p internal Xtal, minimum components and a RFM12B module to do the sending/receiving and then connect it to my Pi0W via the serial port and 3v3 and drive all "send RF" comms that way.
by MarkDH102
Fri Mar 29, 2019 7:11 am
Forum: Troubleshooting
Topic: VNC Interface won't stay enabled
Replies: 15
Views: 669

Re: VNC Interface won't stay enabled

This really needs sorting or a sticky being put up somewhere. It seems to be catching a lot of people out.
Is it a bug in the kernel? Why after many years of VNC working fine has it suddenly started happening?
by MarkDH102
Tue Mar 19, 2019 4:34 pm
Forum: Troubleshooting
Topic: SOLUTION: VNC does not start on a headless Raspberry pi.
Replies: 7
Views: 1327

Re: SOLUTION: VNC does not start on a headless Raspberry pi.

Many thanks for this - I've just been redirected here from my own thread.
Works for me...
by MarkDH102
Tue Mar 19, 2019 4:33 pm
Forum: Troubleshooting
Topic: Why does my RealVNC start so late after boot up
Replies: 2
Views: 134

Re: Why does my RealVNC start so late after boot up

Many, many thanks for this pointer.
I now have a working system again.
I was beginning to tear my hair (what's left of it) out!
by MarkDH102
Tue Mar 19, 2019 7:29 am
Forum: Troubleshooting
Topic: Why does my RealVNC start so late after boot up
Replies: 2
Views: 134

Why does my RealVNC start so late after boot up

Here is my syslog from boot up to when RealVNC starts up. Obviously, I can't VNC in to my Pi until the service starts... To my untrained eye, I can't see anything untoward. Maybe the entries prior to reboot give a clue to somebody? Stretch - completely up to date, Pi0W. Mar 18 16:41:51 scraper vncse...
by MarkDH102
Wed Mar 13, 2019 3:43 pm
Forum: Troubleshooting
Topic: Pi0 W showing "no wireless interface" and won't connect via VNC
Replies: 2
Views: 124

Re: Pi0 W showing "no wireless interface" and won't connect via VNC

Ok, I am now beyond angry. I burned an old image from 3/3/18 to a backup card and it all worked. I then did an update & upgrade which took a looooooong time. It all still worked. I then did a dist-upgrade. Now, I can't get into VNC no matter what I do. It boots up, displays the desktop on my monitor...
by MarkDH102
Wed Mar 13, 2019 11:16 am
Forum: Troubleshooting
Topic: Pi0 W showing "no wireless interface" and won't connect via VNC
Replies: 2
Views: 124

Re: Pi0 W showing "no wireless interface" and won't connect via VNC

I've now put the SD card back in the original Pi0 W and lo and behold it is no longer seeing the WiFi in that one either.
What on earth could I have done wrong?
Incredibly frustrating - all resulting from an extremely brief power cut.
Thank goodness most of my stuff has been migrated to esp32's now...
by MarkDH102
Wed Mar 13, 2019 9:22 am
Forum: Troubleshooting
Topic: Pi0 W showing "no wireless interface" and won't connect via VNC
Replies: 2
Views: 124

Pi0 W showing "no wireless interface" and won't connect via VNC

My router lists the device. However, if I plug in a (non powered) 3 port USB hub with ethernet (not connected to anything), I am able to VNC in over the WiFi with no problems ??? It still says "no wireless interfaces" and only shows the ethernet connector icon in the menu bar. But it does show wirel...
by MarkDH102
Mon Mar 11, 2019 7:10 am
Forum: Python
Topic: Send hex commands via uart port
Replies: 4
Views: 302

Re: Send hex commands via uart port

The code looks fine to me. I use exactly the same type of thing to talk to a serial LCD. I guess you have the baud rate etc. correct for the camera. It strikes me that the 2 byte command you are sending is a bit "light". Are there no checksums involved or message terminating characters like carriage...
by MarkDH102
Wed Mar 06, 2019 5:32 pm
Forum: Troubleshooting
Topic: How to fix WiFi failure without rebooting
Replies: 2
Views: 97

Re: How to fix WiFi failure without rebooting

To turn off power saving mode with Edimax WiFi dongle, I do the following :

sudo nano /etc/modprobe.d/8192cu.conf

And add the 2 lines below then save.

# Disable Power Management
options 8192cu rtw_power_mgnt=0 rtw_enusbss=0

I too was plagued by the same problem, but not since doing this.
by MarkDH102
Wed Mar 06, 2019 5:25 pm
Forum: General discussion
Topic: Raspberry Pi3 connectivity from mobile
Replies: 4
Views: 154

Re: Raspberry Pi3 connectivity from mobile

You might wish to try weaved.com
I used it for something similar a while back.
I used it a while back. I have no idea if it still works the way Linux keeps changing the goalposts...
by MarkDH102
Sun Mar 03, 2019 7:17 am
Forum: Beginners
Topic: High CPU usage?
Replies: 7
Views: 333

Re: High CPU usage?

In Python : x = 0 while True : x = x + 1 Will use 100% CPU (on a Pi0) or 25% (on a 4 core Pi model). import time x = 0 while True : x = x + 1 time.sleep(1) # 1 second Will use next to no processing power. However while the sleep is active, your code is not running. Even using (0.01) (10mS) in the sl...
by MarkDH102
Sun Mar 03, 2019 6:59 am
Forum: AIY Projects
Topic: Does Google AIY still work on the Raspberry Pi?
Replies: 7
Views: 753

Re: Does Google AIY still work on the Raspberry Pi?

Also, Dougie, I assume you did not use Google's image file, but instead worked through their HACKING (https://github.com/google/aiyprojects-r ... HACKING.md) instructions? I used the hacking method and had no issues getting it to work with my own microphone (a USB one from a Nintendo Wii game!) and...

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