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by hampi
Tue Mar 17, 2015 5:46 pm
Forum: General discussion
Topic: POE support on Rpi 3
Replies: 107
Views: 19432

Re: POE support on Rpi 3

Never used POE but it seems to have some advantages http://www.instructables.com/id/Power-Over-Ethernet-Router-Conversion/ http://www.instructables.com/id/PiPoE-powering-a-Raspberry-Pi-over-Ethernet/ So it means adding some modular 8P8C connectors and a DC power converter to the Raspberry Pi. Nice p...
by hampi
Fri Mar 13, 2015 7:15 pm
Forum: Automation, sensing and robotics
Topic: When you need more power - how to be safe?
Replies: 17
Views: 3556

Re: When you need more power - how to be safe?

The ARRL Handbook for radio amateurs , Practical Design and Projects and there chapter on Safety . The RSGB might have a similar book. The power supply module is normally put into a separate closed metallic enclosure. This enclosure is connected to safety ground via the mains cable. Depending on you...
by hampi
Thu Mar 12, 2015 6:03 pm
Forum: General discussion
Topic: PSU Monitor
Replies: 3
Views: 768

Re: PSU Monitor

With the modern lightweight and high capacity battery technology you do not have other possibility than to closely monitor the battery charge state. Otherwise the battery life might be very short or it might even explode. The measured voltage does not tell you practically anything about the charge s...
by hampi
Fri Mar 06, 2015 7:47 pm
Forum: Beginners
Topic: L298N chip question
Replies: 6
Views: 835

Re: L298N chip question

You do not need Raspberry Pi to test that board. The L298N needs two separate power supply lines and of course ground connection. Connecting a jump wire from one of the inputs to logic high (usually about 5 V) should start to turn the motor. Do not connect the logic input to motor power supply since...
by hampi
Wed Mar 04, 2015 10:02 pm
Forum: Other projects
Topic: Solar Project not yielding expected results
Replies: 3
Views: 729

Re: Solar Project not yielding expected results

10 hours/day is not that bad, but it all depends on the load (Raspberry Pi model and accessories), season and weather conditions. One thing to be aware of is that the "CMP 12 Solar controller" consumes current below 20 mA continuously. Thus it takes in the worst case 24 h x 0.02 A = 0.48 Ah of the s...
by hampi
Tue Mar 03, 2015 9:20 pm
Forum: Other projects
Topic: How To Build A PSU For My RPI B+ Project
Replies: 3
Views: 678

Re: How To Build A PSU For My RPI B+ Project

Here is some info

http://elinux.org/RPi_5V_PSU_construction

You will need a switching mode power converter with a reasonable efficiency, but for hobby use it is better to do that from low voltage (typically 6 - 24 V) than directly from mains power.
by hampi
Mon Mar 02, 2015 12:28 pm
Forum: General discussion
Topic: Scheduled reboot for system health?
Replies: 5
Views: 1139

Re: Scheduled reboot for system health?

Is there any benefit to this at all? In my opinion only if you want to save in battery use or have otherwise limited energy source to keep the system up. Or just do not like the idea of keeping the system up all the time. As an example nobody will break into your system if it is powered down and th...
by hampi
Sun Mar 01, 2015 8:14 am
Forum: General discussion
Topic: i2c issue - attiny85
Replies: 5
Views: 3370

Re: i2c issue - attiny85

Never used attiny85 but that looks like a bug in the i2c implementation of attiny85. You could test that with a more robust chip first to see that your Python program is working correctly. You might also need a logic analyser to see what is happening on the i2c bus. BTW you are using an old Raspberr...
by hampi
Sat Feb 28, 2015 9:19 am
Forum: Automation, sensing and robotics
Topic: HOW-TO Build an Automatic Power Supply for the Pi
Replies: 39
Views: 40767

Re: HOW-TO Build an Automatic Power Supply for the Pi

You have really put some effort on that one and written long documentation. I need to read it again more carefully. Some quick notes from me. The switching mode regulators like LM2576 and others usually have a shutdown pin, which can be used stop and restart the 5 V power supply for RPi. For testing...
by hampi
Sun Feb 22, 2015 5:32 pm
Forum: Beginners
Topic: GPIO inputs and outputs
Replies: 2
Views: 455

Re: GPIO inputs and outputs

This might be useful for the pullups and pulldowns using device tree:

https://github.com/fivdi/onoff/wiki/Ena ... spberry-Pi
by hampi
Sat Feb 21, 2015 1:22 pm
Forum: Beginners
Topic: Weather Station Question
Replies: 5
Views: 815

Re: Weather Station Question

Some I2C sensors and code here (there are other chips available too)

https://github.com/oh7bf/I2C-modular-co ... pters/wiki

I did a small system last Christmas where RPi web server was showing the data stored in local SQLite database using PHP scripts.
by hampi
Fri Feb 20, 2015 8:14 pm
Forum: General discussion
Topic: connect raspberry pi to PIC micro controller
Replies: 8
Views: 1618

Re: connect raspberry pi to PIC micro controller

Here is one educational example with FET level shifters

https://github.com/oh7bf/RasPiHBridge
by hampi
Fri Feb 20, 2015 8:48 am
Forum: General discussion
Topic: the birdbox project and rain...
Replies: 5
Views: 1228

Re: the birdbox project and rain...

Half open wooden box works for me. Most important thing is that the rain does not drop directly on the electronics. See the page and the github link there

https://twitter.com/RPiAOne

Edit: winter photo in snow https://www.flickr.com/photos/oh7bf/16591362231/
by hampi
Wed Feb 18, 2015 6:40 pm
Forum: Advanced users
Topic: GPIO use with Fldigi
Replies: 3
Views: 1472

Re: GPIO use with Fldigi

The serial interface is

Code: Select all

/dev/ttyAMA0
More info from http://elinux.org/RPi_Serial_Connection .
by hampi
Thu Feb 12, 2015 8:45 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: writing I2c Chareter driver Example
Replies: 7
Views: 3176

Re: writing I2c Chareter driver Example

This document must be more upstream than elinux.org

https://www.kernel.org/doc/Documentatio ... -interface
by hampi
Thu Feb 12, 2015 6:51 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: writing I2c Chareter driver Example
Replies: 7
Views: 3176

Re: writing I2c Chareter driver Example

Please tell me how to read multibyte data from the i2c device by using ioctl and normal read calls. My read/write I2C C code is almost copy-and-paste from http://elinux.org/Interfacing_with_I2C_Devices I start usually with a small test program that reads one byte from the chip. When that works it i...
by hampi
Wed Feb 11, 2015 8:08 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: writing I2c Chareter driver Example
Replies: 7
Views: 3176

Re: writing I2c Chareter driver Example

I have I2C daemon (service) C codes for chips htu21d, mag3110, mpl3115a2 and tmp102 in my github https://github.com/oh7bf?tab=repositories These are easy userland programs when you do not need very fast "real time" reading of the chips - the weather data is one example. They do not use I2C clock str...
by hampi
Fri Jan 23, 2015 8:52 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: DS2406 reset problem
Replies: 3
Views: 788

Re: DS2406 reset problem

Ideally you could use a scope or a logic analyser to see what goes wrong. First thing to do is to try with a shorter cable and make sure that there are no ground loops. If the problem is RFI (radio-frequency-interface) ferrite beads on the cable or RC-filter might help. The 1-wire can be laborious b...
by hampi
Fri Jan 23, 2015 1:04 pm
Forum: Beginners
Topic: Running a script automatically
Replies: 24
Views: 2209

Re: Running a script automatically

cron is fine if the system stays up and the clock stays at correct time for 24h/day - which is not the case if the system boots up randomly and has a weak WiFi connection. anacron might be better in such a case. The system time might jump quite a lot when the network connection is finally establish...
by hampi
Wed Jan 21, 2015 9:55 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Interfacing using I2C ADC with RPi B+
Replies: 1
Views: 668

Re: Interfacing using I2C ADC with RPi B+

The Adafruit seems to have some Python code. C code should not be that difficult either. Basically writing bytes to and reading bytes from the character device /dev/i2c-1 (or /dev/i2c-0 in old models). But you need to read the ADS1115 datasheet first to understand how the data is presented at bit le...
by hampi
Wed Jan 14, 2015 10:36 am
Forum: Troubleshooting
Topic: continuous servo code needed
Replies: 3
Views: 862

Re: continuous servo code needed

That sounds similar to my advanced DIY project

https://github.com/oh7bf/RasPiHBridge/wiki

I was testing that briefly with a DC motor

https://github.com/oh7bf/RasPiHBridge/w ... ion-Sensor

BTW this topic is more in "Automation, sensing and robotics" category.
by hampi
Tue Jan 13, 2015 1:43 pm
Forum: General discussion
Topic: Data logging and storing in separate files with time stamps
Replies: 2
Views: 1320

Re: Data logging and storing in separate files with time sta

Probably the easiest way is to install SQLite. Each database is a single file. You can find good documentation about SQLite from web. For example create a new database testbase.db and create an empty table temperature with a time stamp to it sqlite3 /tmp/testbase.db sqlite> create table temperature(...
by hampi
Mon Jan 05, 2015 9:19 pm
Forum: General discussion
Topic: who advice I2C humidity
Replies: 1
Views: 631

Re: who advice I2C humidity

For example HTU21D

Code: Select all

git clone https://github.com/oh7bf/Htu21d.git
and follow instructions in the install file.
by hampi
Sun Jan 04, 2015 8:52 am
Forum: Automation, sensing and robotics
Topic: What's the best way to phyiscally connect sensors to your Pi
Replies: 20
Views: 4843

Re: What's the best way to phyiscally connect sensors to you

I was testing modular 4P4C connectors recently. They seem to work ok for slow speed two wire I2C and have been used on one wire for long time already. Here is a photo https://github.com/oh7bf/I2C-modular-connector-adapters/wiki The only inconvenience is that you need a custom made printed circuit bo...

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