Author: GregPayne

Raspberry PI: Bottlepy and Twitter Bootstrap

GregPayne
I have been using my Raspberry Pi for the last few months quite a lot. I am currently working on a temperature/environment monitor that logs temperature, using a DS18B20, and light conditions using an optical sensor. I also have two LED’s and two buttons to test basic input and output.
I am developing the application in python using the BottlePy framework. I chose the BottlePy framework as it is a single file that you add, it is very small and it works with Python 3. To control my GPIO’s, I am using the Quick2Wire library. To display the temperature data, I am using Google Charts.

This is a picture of the main temperature logging page so far.
However, the purpose of this post is to show how to integrate BottlePy and Bootstrap by Twitter. According to their website, Bootstrap is a “Sleek, intuitive, and powerful front-end framework for faster and easier web development.”
To display this, I am going to use my GPIO code which reads buttons and turns on LED’s through a webpage. 

To start off we need python file that will run as the server. Below is a snippet of code. The @route shows that this particular function will be run when /gpio us entered into the browser. The webpage is broken up into four sections. The first controls LED 1, the second controls LED 2, the third gets the state of both buttons and light sensor and then the fourth runs a .c file to flash the LED’s.
Now we need to have a look at the html code that creates the webpage. By default, Bootstrap works with the user downloading the .css and .js file. These are then statically linked to the html code. When using the BottlePy framework, I haven’t found a way to return a webpage template, AND a static file. Therefore I have found a link where the .css and .js files have been hosted. By using these links, you only have access to the default settings, but they are enough for what I am wanting to do.
You have to link to the .js and .css file and then by using certain classes that have been defined and explained on the Bootstrap website, you can get nice looking buttons, navigation bars, and tables. They have many options to use but these are the three that I used here for my site. 
When a button on the website is pressed, it sends the value back to the python function and the python code will perform the task. With the Flash LED button, the python code calls a .c file that has been compiled and runs when called. 
When requesting the button state, I return hex formatted colours to show the state of the buttons. These the colour in the table. 

The red shows that Button 1 has been pressed, the Green shows that Button 2 is not pressed and the Blue shows that the light level is currently light.
There are many different elements that can be added by using the Bootstrap framework. The documentation is really clear and easy to follow with many examples. 
If you get stuck or need some more explanations give me a shout.
Greg

Raspberry Pi: Changing time zones

GregPayne
By default the time zone on the Raspberry Pi image is set the the UK. As there is no RTC on the Raspberry Pi, when ever it is turned on, the time is synced. To set the time zone to your local area, in my case South Africa, the configuration of the tzdata package needs to be changed.

sudo dpkg-reconfigure tzdata

Select your territory.

Then select your local time zone.

As you can see the time zone has now been changed.

Greg

Raspberry Pi: Using Bottlypy to control GPIO

GregPayne
I have been trying for a few days now to get control over the GPIO pins through a webserver. There are a number of tutorials on the web but having very little web programming experience, I struggled to understand and follow the tutorials. 
After working through a number of examples, and not getting what I want, I came across the bottlepy framework. The tutorial on their website and the todo example show enough ways on how to get data to an html page and how to get data from an HTML page.
I have been super busy at work and also trying to get it to work so haven’t had a chance yet to do a bit of an explanation on what I did.
To download the files I used click here.
You will need to edit your IP address in the index.py file.
Change to the directory on your Raspberry Pi and run $ python3 index.py
In your browser navigate to IPaddress:8080/index then follow the links. Have a look in index.py to see what pins I have used for the inputs and outputs.

Sorry this is so vague but as soon as I get a chance I will update this post with some more explanations.

Greg

Raspberry Pi: GPIO input and output

GregPayne
So I got my Raspberry Pi yesterday and am super excited. I feel like a 10 year old on Christmas morning. I had already loaded the the Raspbian image onto an SD card so as soon as I got it I powered it up and away it ran.
The first thing that I wanted to get working was the GPIO pins. I did a bit of reading and some basic python examples and away I went. Have a look at this website for a very decent crash course in python.
The first thing you need to do is import the GPIO module. This can be installed from here. 
Then you need to tell python that you are going to use the Raspberry Pi’s pin numbers when referencing the ports. The direction of the port is then set.
Once the setup is complete, you can start your code. In my hardware, I connected a push button switch to pin 11 and pin 18 and an LED to pin 3 and pin 5.
import RPi.GPIO as GPIO

#use the Raspberry Pi pin numbers
GPIO.setmode(GPIO.BOARD)

#set the input with pull up control
GPIO.setup(11, GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.setup(18, GPIO.IN, pull_up_down=GPIO.PUD_UP)

#set the output pins
GPIO.setup(3, GPIO.OUT)
GPIO.setup(5, GPIO.OUT)

while 1:
 if GPIO.input(11):
  GPIO.output(3, False)
 else:
  GPIO.output(3, True)

 if GPIO.input(18):
  GPIO.output(5, False)
 else:
  GPIO.output(5, True)
Above is the python code that I used. If you want to download the file you can get it here.

Once you have the file saved, run it in python and by pressing the buttons, the LED’s will turn on. To stop the program running, press CTRL+z.

Greg

C# dll for programming Microchip PIC’s

GregPayne 2 Comments
In the test development environment, the need often arises where a microcontroller needs to be programmed before the testing can be completed. This can either be done with the development environment or through the command line if this method is provided for by the manufacturer. 
Programming in the IDE is nice and easy, but very slow and needs the user to press the buttons. Often in the test environment, this process needs to be automated with as little user input as possible. Here is where using the command line parameters comes in so handy. You will need this hard-to-find document which outlines the commands to use.
In my application I am programming the PIC18LF26K22 microcontroller from Microchip and using the MPLAB PM3 device programmer. To test the devices I am using LabVIEW and TestStand from National Instruments. 
There is a provision in LabVIEW where you can run command line programs, but I have found this to be a bit slow when interfacing with the PM3 programmer. This made me think of writing a C# dll to perform this task. Now I am no expert at C# programming, but am trying to learn where I can so thought this would be a good exercise. 
I started off be investigating the Process Class and found just what I was looking for. All you need to do is create a new object of the Diagnostics.Process class. Then build the string that you need to send. The make up of this string is explained in pdf attached above. 

public bool LoadImageToPm3(string pm3CmdPath, string port, string hexImagePath)
        {
            System.Diagnostics.Process proc = new System.Diagnostics.Process();
            proc.StartInfo.FileName = pm3CmdPath;
            proc.StartInfo.Arguments = "/" + port + " /P18LF26K22 /F" + '"' + hexImagePath + '"';
            proc.StartInfo.RedirectStandardOutput = true;
            proc.StartInfo.UseShellExecute = false;            
            try
            {
                proc.Start();
                strStandardOutput = proc.StandardOutput.ReadToEnd();
                proc.WaitForExit();
                int iSuccessful = strStandardOutput.IndexOf("Operation Succeeded");
                if (iSuccessful > 0)
                {
                    return true;
                }
                else 
                {
                    return false;
                }
            }
            catch (SystemException e)
            {
                return false;
            }
        }
This is an example of how to load an image onto the PM3. I build the string and then once I start the process, I read the standard output to make sure the the operation was successful.

The dll I wrote can handle loading an image to the programmer, program a device where the image is already on the programmer and erase the device. There are many other processes that can be performed but for the production testing that I am doing, this is all I need.

In the project attached, I also wrote a simple form application and a TestStand sequence to test the dll. You can find those files here.

By using a dll, I decreased my programming time from 60sec in LabVIEW to 15sec. When the device being tested only takes 30sec to test, an extra 45sec programming time is huge.

I hope this helps and if you need anything explained further, please leave a comment and I will try help where I can.

Greg