Currently, I am using an Asus X200M netbook with ubuntu 14.04 lts. The keyboard of the netbook is slighly small compared to regular laptop. This is a slight drawback of all netbooks. For me it took only a couple of hours to get adjusted to the new keyboard.
However, while typing, my thumb inadertently touches the touch pad and the cursor jumps to some random location. I am always using an external mouse for navigation as I dont like to use t touch pad . So I decided to find out a way to disable the touch pad when I am typing long documents.
Here are the steps for disabling and enabling touch pad.
Find out the device id of your touch pad. Open a terminal and type
$ xinput list
Look for the id of your touch pad. In my case the touch pad is detected as a logitec mouse and the id is 13. The other mouse shown in the figure is my external mouse. If in doubt, remove the external mouse and re run the command to find out the correct device id.
In order to disable touch pad type the following command.
$ xinput set-prop 13 "Device Enabled" 0
You can eneable the touch pad by changing 0 to 1 in the command above.
I have been tinkering with NodeMCU devkit boards recently. The easiest way to program these little beasts is to use arduino platform and install the compilers and other tools from . Unfortunately the stock arduino shipped with ubuntu 14.04 is quite old. You need a recent version of arduino software. to get the esp8266 board working.
Here is what I did.
Removed the existing arduio installation
My nodeMCU collection.
$ sudo apt-get remove arduino
Download the appropriate arduino software from arduino.cc. This is available for both 32 bit and 64 bit editions. Choose the correct version.
The arduino software platfrom is written in Java. So install java runtime.
$ sudo apt-get install openjdk-7-jre
Unzip the arduino software and move it to an appropriate location. I moved it to /opt.
tar -xJf arduino-1.6.4-linux64.tar.xz
sudo mv arduino-1.6.4 /opt
Add appropriate path to .bashrc file.
I added PATH=$PATH;/opt/arduino-1.6.4/bin. Change it according to your arduino location and version.
Open a terminal and execute the new arduino.
We resently bought several Asus X200 series netbooks for our faculty members. The main attraction of this cute netbook is its light weight and a built in HDMI port. We plan to use them extensively for content delivery in class rooms. These machines are really cheap, costing around Rs17000 ( around $260). The base model comes with Intel® Celeron® Dual-Core ~ 2.58 GHz Processor and 2GB ram, DOS operating system. It has an 11.6 inch LED display.
Our idea was to put ubuntu 14.04 and deploy the machines. The machine has an ethernet port and wifi port. Installation of Ubuntu 15.10 was a smooth affair. Unfortunately, the broadcom wifi interface did not work out of the box. Here is what I did to fix the issue.
- Find out which wifi chip is used.
The wifi chip is Broadcom Corporation BCM43142. You have to download and compile the kernel module for this chip.
2) Make sure that the machine is connected to internet and the apt sources are properly set up
3) Update the machine
$ sudo apt-get update
4) Finally instal the bcmwl driver.
$ sudo apt-get install linux-headers-`uname -r` dkms build-essential bcmwl-kernel-source
This will downlad necessary driver your wifi will be up and running. The above line installs dynamic kernel module support and compiles the broadcom wireless driver.
I have been toying with the idea of making a Si5351A breakout board ever since I saw the chip details on Silicon labs web site. It seems SI5351A is an ideal choice for Variable Frequency Oscillator (VFO) for a homebrewed radio. The SI5351 is an i2c programmable any frequency clock generator. The chip can generates up to 8 non-integer-related frequencies from 8 kHz to 160 MHz depending on the model. There are 3 different variations of the chip currently available. For the home brewer SI 5351A looks promising as it is available in a 10 pin MSOP package.
For the ham radio home brewer, such a chip which can be programmed over many ham bands offer numerous possibilities. The most obvious choice would be as a VFO. Currently, the analog devices DDS chips are ruling the market. Compared to them the Silicon Labs chips are cheaper and less cumbersome to handle. I am yet to see the noise performance of these two chips compared.
In fact, there are a couple of commercial Si5351A breakout boards targeted at the home brewer. They cost around 10$. But the chip itself cost only 1.33$ on the Silicon Labs website and you need only a few additional components to complete the board. The total cost need not be more than 3 $. Along with a cheap Arduino clone, Si5351A gives you lot of flexibility. An added advantages is that the SI5351A has three independent programmable clock generators. You can combine the VFO and BFO into a single chip.
My idea was to build a single side PCB so that any one can build one via toner transfer. Last week, I had a long chat with my friend and colleague Amal Dev about designing a simple board. The board routing was done by Amal Dev on eagle, We have designed an experimental single sided board and it may not be conforming to RF design principles always.
For the interested home brewer a toner transferable image is here. You can buy the SI5351 from RS components or from Mouser. The board is to be powered from a 5v source. The SI5351A needs 3.3v for its operation. The LM1117 is used for generating this. Note that the LM1117 is SMD and is soldered on the copper side. The two MOSFETs ( BS170) are used to convert the I2C levels from 5v to 3.3v. Check the pin outs before you solder. The board can be directly powered from an arduino.
For programming the board you can try the example code from Hansummers. Alternately you can try the excellent si5351 arduino library. Tom Hall AK2B has some sample sketches using this library. Please note that I2C address of the chip may be different from those found in the above code. Please use an I2C scanner to find out your chips address and then modify your code accordingly.
Schematic of si5351 breakout board. Q1 and Q2 are bs170. The regulator is a smd lm1117
Si 5351 board.
Component Placement on the Si5351 break out board.
The pin out of the SI5351A is shown below.
A special thanks to Amogh Desai who tested the first version and reported couple of errors. Further comments and error reports are welcome.
I have been trying to program cheap Chinese DDS modules recently. I wanted to add a DDS VFO to one of my bitx rigs. These modules are available at $4.5 from aliexpress. They claim that it can work up to 40Mhz.
I used an arduino Uno along with a rotary encoder for controlling the module. The DDS module pin out is shown below.
The connections to arduino and rotary encoder is shown below.
You can download the code hosted on github from here.
The code is for 40m VFO with IF of 9Mhz. You can easily modify it for other bands and IFs. Additional functions can be programmed easily.
The DDS modules are available on line form from many sources. The rotary encoder can be obtained from element14.