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by bertlea
Wed Sep 18, 2019 7:18 am
Forum: Advanced users
Topic: A compiled, working Node.js on 3B+
Replies: 2
Views: 35

Re: A compiled, working Node.js on 3B+

If you are running Raspbian (Buster or Stretch), the latest Node.js versions (v10.x.x and v12.x.x) should be supported. If you do not have it already installed, you can just install it using apt-get. sudo apt-get update sudo apt-get install nodejs Raspbian (or Debian) Jessie seems only support versi...
by bertlea
Mon Sep 02, 2019 8:03 am
Forum: Troubleshooting
Topic: Error with tensorflow and keras
Replies: 1
Views: 82

Re: Error with tensorflow and keras

Just guessing: How big is your model? I see the error message: "Could not allocate ndarray". I suspect it is related to memory (RAM) limits as the Pi 3 only got 1G RAM shared by CPU and GPU.
by bertlea
Thu Aug 29, 2019 3:38 am
Forum: General discussion
Topic: Raspberry Pi 4 overheat : why not underclocking a little ?
Replies: 24
Views: 1436

Re: Raspberry Pi 4 overheat : why not underclocking a little ?

My attempt to under-volt/under-clock did not success yet. See the post:

https://www.raspberrypi.org/forums/view ... 9#p1527629

If anyone got some effective under-clock/under-volt settings, it will be nice to share.
by bertlea
Thu Aug 29, 2019 3:34 am
Forum: General discussion
Topic: Underclocking Pi4 to Pi3B level
Replies: 6
Views: 543

Re: Underclocking Pi4 to Pi3B level

Tried to under-clock the Pi4 last night by adding the settings below in config.txt file but it does not seem to be effective... maybe only 1 degree Celsius difference (keep running around 64 regardless the settings). This setting is actually more effective on my Pi3B+. On Pi3B+ that seems to lower t...
by bertlea
Tue Aug 27, 2019 6:59 am
Forum: General discussion
Topic: Underclocking Pi4 to Pi3B level
Replies: 6
Views: 543

Re: Underclocking Pi4 to Pi3B level

Thank you @ProDigit. I guess I have to do some trail and error work based on your suggestions on this later. I am just not sure can I try out different values of these parameters freely or there are implied constraints such as the arm_freq or core_freq need to keep certain ratio to sdram_freq, etc. ...
by bertlea
Mon Aug 26, 2019 6:48 am
Forum: General discussion
Topic: RasPi 4 is on RDP slower than the RasPi 3
Replies: 15
Views: 1094

Re: RasPi 4 is on RDP slower than the RasPi 3

@insidERR, I think dom meant you use the command “sudo raspi-config” and go to “Advanced Options” --> “GL Driver” and select “Legacy” driver and then press “<Ok”>… Then reboot.
by bertlea
Thu Aug 22, 2019 1:23 am
Forum: General discussion
Topic: Underclocking Pi4 to Pi3B level
Replies: 6
Views: 543

Underclocking Pi4 to Pi3B level

I would like to seek advices specifically on underclocking Pi4 (4G RAM) to have processing power close to Pi3B. The reason is simply that I do not need processing power more than the Pi3B, but I really want to run it cooler, especially in idle time. The main reason I bought a Pi4 is I want its 4G RA...
by bertlea
Wed Aug 21, 2019 8:29 am
Forum: General discussion
Topic: Uses for Raspberry Pi Zero/Zero W?
Replies: 81
Views: 2753

Re: Uses for Raspberry Pi Zero/Zero W?

I use it to run web servers and monitor other servers' status, sending alerts to my email if it sees anything unusual. It also serve as a secondary backup servers to store "older" versions of files I got just in case I have issues with latest files, so I can fall-back to some earlier versions. The P...
by bertlea
Wed Aug 21, 2019 4:50 am
Forum: General discussion
Topic: Ideal SD Card Size for Raspberry PI 4
Replies: 16
Views: 650

Re: Ideal SD Card Size for Raspberry PI 4

If cost is not a factor, then larger is better. It may not make the start-up faster, but it will have longer life and potential spare spaces for user files and able to increase swap space to a much larger size (in case needed in future). Generally I use 16G for Raspbian Lite and 32G for Raspbian des...
by bertlea
Wed Aug 14, 2019 2:45 am
Forum: General discussion
Topic: Pi Zero W, VS 3B+, VS 4 for low CPU applications?
Replies: 24
Views: 1679

Re: Pi Zero W, VS 3B+, VS 4 for low CPU applications?

I have all 3 models you mentioned and use them in different use cases. The main differences of use cases is not how demanding of the CPU usage but requirements of RAM. For Raspbian Lite based web servers, just watching downloaded video, play music (using omxplayer) I found Pi-0W is perfect. For runn...
by bertlea
Wed Aug 14, 2019 2:30 am
Forum: General discussion
Topic: Fast turn off of a Pi in embedded applications
Replies: 20
Views: 900

Re: Fast turn off of a Pi in embedded applications

For a Raspbian based solution that allow safe power-off (simply unplug) is done by Pimoroni for their Keybow products. The requirements for SD card is very simple that only a sufficient space in FAT32 is needed. https://github.com/pimoroni/keybow-firmware However this is only for you to consider the...
by bertlea
Sun Aug 04, 2019 12:40 pm
Forum: Python
Topic: Flask security issue
Replies: 12
Views: 459

Re: Flask security issue

Not a direct answer, just some feedbacks on your query: You code only use GET method, so everything is in the URL, there is no need to use postman. Just use browser or curl command to test should be fine. I believe you only need tools such as Postman when you use POST method. I do not see any jwt li...
by bertlea
Thu Aug 01, 2019 3:17 am
Forum: Python
Topic: Flask security issue
Replies: 12
Views: 459

Re: Flask security issue

The “security risk” for such setup I can think of: 1. Because of "http", all apikey / MySecretKey will send over the Internet in plain text, anyone / equipment have access to the network path in between can have them. 2. Potential SQL injection as your system allow user make changes to the database....
by bertlea
Tue Jul 30, 2019 6:16 am
Forum: Python
Topic: Flask security issue
Replies: 12
Views: 459

Re: Flask security issue

Over http or https? Is your apikey a secret to the user or to your system? I guess that also depends on what will be in your "#do something” block. For example it may have security holes if your “#do something” code will process user inputs sent over the API such as construct a query to the database...
by bertlea
Wed Jul 24, 2019 9:04 am
Forum: Beginners
Topic: Guidance on dynamically/asynchronously updating web page requested
Replies: 4
Views: 162

Re: Guidance on dynamically/asynchronously updating web page requested

Depends on what/how you implemented your backend (web server). If you are using Node.js, then I recommend the package: “ws”. https://www.npmjs.com/package/ws You can visit the link above and there are some sample codes. I believe other backend such as Python with Flask also have package supports web...
by bertlea
Wed Jul 24, 2019 1:42 am
Forum: Advanced users
Topic: How to make rpi0-w RAM 128MB from 512MB
Replies: 4
Views: 271

Re: How to make rpi0-w RAM 128MB from 512MB

Thanks @jahboater, yes, ramfs is more appropriate in this case. User can create a file with size (352M - 100K?) in ramfs to simulate a 128M + 32M gpu case.

Now, I think may be it is more certain and easier to just write a c program and allocate 352M size without releasing it.
by bertlea
Tue Jul 23, 2019 11:39 pm
Forum: Advanced users
Topic: How to make rpi0-w RAM 128MB from 512MB
Replies: 4
Views: 271

Re: How to make rpi0-w RAM 128MB from 512MB

How about creating a 352M tmpfs ram disk to leave only 128M usable for the OS?
by bertlea
Tue Jul 23, 2019 11:12 pm
Forum: Beginners
Topic: Guidance on dynamically/asynchronously updating web page requested
Replies: 4
Views: 162

Re: Guidance on dynamically/asynchronously updating web page requested

Use websocket, you can push data to update the web page.
by bertlea
Thu Jul 18, 2019 7:50 am
Forum: Beginners
Topic: web server on raspberry pi
Replies: 2
Views: 154

Re: web server on raspberry pi

I am running a web server which got some http/https services and also got some customized services I wrote myself. I am not using any specific platform such as tomcat, ngix, etc. I use only the node.js running in REPL mode on tmux session. This gives me the most flexibility I want. I guess I have th...
by bertlea
Wed Jul 17, 2019 8:10 am
Forum: General discussion
Topic: Raspberry PI Web Server
Replies: 19
Views: 1128

Re: Raspberry PI Web Server

If you only expose the web services (e.g. http, https), just Keep your OS up-to-date, especially when there is an security alert issued then it is pretty safe. But if you also expose ssh, then you better take more measures to protect from attackers. use a long and secure password don't use default p...
by bertlea
Tue Jul 16, 2019 7:26 am
Forum: Beginners
Topic: IP connection by key
Replies: 3
Views: 132

Re: IP connection by key

How far is your mailbox from your home? If it can still access you home wifi, then you don’t need “public service” with fixed IP. You just assign a fixed “internal” IP address to your RPi and all communication can be done using that fixed IP.
by bertlea
Tue Jul 16, 2019 6:53 am
Forum: Beginners
Topic: [SOLVED] Asynchronously send email in python?
Replies: 8
Views: 322

Re: Asynchronously send email in python?

Is there a better way to watch a variable for changes? You can try adding a "sleep" function call inside your while loop. You need to import time for that. You can adjust the sleep time (such as 0.5) to suit your need, the number is in seconds. Example: import time def sendQueue(): #left always run...
by bertlea
Fri Jul 12, 2019 3:59 am
Forum: Beginners
Topic: Using pi to show images on connected HDMI
Replies: 6
Views: 263

Re: Using pi to show images on connected HDMI

I believe that there is at least one video player program that doesn't require X, but since I've never needed to do that, I don't know what it is.
omxplayer?
by bertlea
Fri Jul 05, 2019 4:26 am
Forum: Troubleshooting
Topic: Help with log files and seeing what is/was going on.
Replies: 10
Views: 315

Re: Help with log files and seeing what is/was going on.

You can try journalctl -n 1000 This will give you the last 1,000 log entries. You can change the number after "-n" to suit your needs. If you have some keywords you can filter to log such as "carrier", you can pipe the output and use grep to filter it. I used that method to trouble shoot my pi's wif...
by bertlea
Fri Jul 05, 2019 3:50 am
Forum: Beginners
Topic: Something I want to try
Replies: 2
Views: 175

Re: Something I want to try

I guess it is feasible. I think what you described is making the Pi as an wifi access point that allows your tablet to access it and then you run Kodi on that Pi to allow your tablet to watch files the media from it. For access point, I think that is the tutorial you can try: https://www.raspberrypi...

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