Installing and configuring MPLAB X and XC compiler

This post is tested on Ubuntu Linux. But it should work similarly for Mac OS X and Windows.

Step 1: Download MPLAB X and XC compiler

Go to http://www.microchip.com/pagehandler/en-us/family/mplabx#downloads Note that MPLAB X is the IDE but it requires the XC compiler to compile the code. You need to download both of them. For the correct compiler, please check "Which Compiler Is Right For You?" section of this page.

Step 2: Run the installer

forrest@laputa:~/Downloads$ ls
MPLABX-v1.85-linux-installer.run
forrest@laputa:~/Downloads$ chmod a+x MPLABX-v1.85-linux-installer.run 
forrest@laputa:~/Downloads$ sudo ./MPLABX-v1.85-linux-installer.run 

You need to do sudo because MPLAB X will also install driver programs for USB programmers, e.g., PICkit3.

The default installation destination is /opt/microchip/mplabx. But you can install it to other places.

Near the end, you will see a pop-up notification that rebooting is needed after installation. Accept it and wait until the installer finishes. Do not consider that the installer is dead.

If you use GNOME desktop, you should find the program's shortcut under "Applications" -> "Programming" - > "MPLAB  X IDE".

The installer does not work with Unity desktop environment on Linux. You won't find it in Launcher. To run it for the first time, run YOUR_MPLABX_INSTALLATION_DESTINATION/mplab_ide/bin/mplab_ide

Step 3: Configuration

The most important thing is to set XC compiler. Go to "Tools" -> "Options". Then select "Embedded". In "Build Tools" tab, click "Add" button under "Toolchain". Select the correct path to an XC compiler that you need. Finally, click "OK" all the way back.

Also, ensure that you select correct target chip, downloader and compiler for your project as follows.



Now, you can use the IDE to compile your code and download them to your target system - if you have a proper downloader (e.g., PICkit3) configured.

Fixing connection issue between MPLAB X and PICkit3

If you get connection error when using MPLAB X (probably only on Linux) with Pickit 3, follow this order:

1. Power off your target board and disconnect Pickit3 from both your laptop and the target board.
2. Connect PICkit3 with your computer.
3. Connect PICkit3 with your target board. 
4. Power up the target board. 

First contact with Microchip PIC24: upgrading PICkit3 firmware

Short version (for those who just need the solution)

If you get the error message that your PICkit3's firmware is out-of-date, go get MPLAB 8 (only for Windows) and let it upgrade the firmware automatically (click Programmer -> Select Programmer -> PICkit3). Then go back to MPLAB X and program your device (of course, select correct target chip). I cannot believe this solution either. But it is from Microchip's support team.

Full story

I will be team-teaching Embedded System class next semester, with another faculty member who offered this class previously, using Microchip's PIC24 architecture. However, my first contact with PIC24 is very frustrating.

Microchip released a new IDE, MPLAB X, for developing and downloading programs for their chips. Unlike previous one, it supports Linux (whereas ATMEL and Texas Instruments have done years ago). I ordered PICkit3 (the downloader or hardware programmer) and Explorer 16 (the dev kit) from Microchip in the hope to use their technical support later.

Out-of-date firmware in PICkit3

However, downloading programs using PICkit3 and MPLAB X frustrated me a lot. The error message didn't help or the information was not consistent with what happened.

When I first finished a hello-world program and tried to download, I got a self-contradictory error:

Connecting to MPLAB PICkit 3...
Firmware Suite Version.....01.22.08
Firmware type..............dsPIC33F/24F/24H

Your PICkit 3 firmware version is too old. You must have firmware version 01.22.08 or higher to use MPLAB X. Connection Failed.

What?

I tried again and it seems that MPLAB X helped me update the firmware:

Connecting to MPLAB PICkit 3...
Firmware Suite Version.....01.22.08
Firmware type..............dsPIC33F/24F/24H


Downloading Firmware...
Downloading bootloader
Bootloader download complete
Programming download...
Connection Failed.

So I tried again and but even the firmware was messed up:

Connecting to MPLAB PICkit 3...
Firmware Suite Version.....01.22.08
Firmware type..............Unknown Firmware Type


Downloading Firmware...
Downloading RS...
RS download complete
Programming download...
Connection Failed.

Since the firmware was never updated, I contacted Microchip's technical support.

Troubleshooting

After a week, they replied and gave me a very weird solution: updating the firmware using an older version (8) of MPLAB on Windows. I tried and I even got error messages on Windows.

Just when I was about to send the Pickit3 back, I plugged it back to my Linux box for last try and some miracle happened. (I guess what happened was that MPLAB 8 on Windows upgraded the firmware to a version from which MPLAB X kept upgrading.)

Connecting to MPLAB PICkit 3...
Firmware Suite Version.....01.28.90
Firmware type..............PIC18F


Downloading Firmware...
Downloading AP...
AP download complete
Programming download...
Firmware Suite Version.....01.28.92
Firmware type..............dsPIC33F/24F/24H

Target detected
Device ID Revision = 3044

The following memory area(s) will be programmed:
program memory: start address = 0x0, end address = 0x3ff

Programming...
Programming/Verify complete 

Conclusion

It took me 2 weeks just to run a hello-world program. I have to say that Microchip does not pave a way for fresh people to learn their stuff. Just a few example:

• Why did they send me hardware with firmware greatly out-of-date anyway? And this cannot be solved in their latest software. Instead, I need a previous version to do that. This is a broken solution.
• The user guide for Explorer16 freezes at its 2005 version whereas the hardware programmer and IDE have changed a lot since then. For example, I didn't know how to connect the Explorer16 with PICkit3. There are two ways and one might burn your circuit.
• The "official" PIC24 textbook, written by a Microchip engineering, has wrong example programs. Like the very early one below:
  

  int main(void) {
      PORTA=0xff;  
      TRISA = 0;  
      return 0;
  }

  How can you output data to Port A before it is set as an output? The first two lines need to be swapped. You won't get the correct value even in software-emulated debugger.
  
• The unreliability issue of the hardware programmer PICkit3. I will mention it in another post.

Hence, my first contact with Microchip's solution was not pleasant.

multidimensional copy in MATLAB's repmat() and NumPy's tile()

repmat is a MATLAB function. A while ago, I had to translate a MATLAB script into Python and it had a lot of repmat(). However, the doc "NumPy for MATLAB Users" only covers the case to duplicate a matrix in 2D, e.g., repmat(a, m, n). How about repmat(a, [m n p])?

The answer is

numpy.array([np.tile(x, (m,n)) for i in xrange(p)])

Please see my demo below. Please also note that using nested tile, i.e.,

np.tile(np.tile(x, (2,2)), (1,3))

does not help-you still get a 2D matrix.

In [1]: import numpy as np

In [2]: x=np.array([[1,2,3],[4,5,6]])

In [3]: np.tile(x, (2,2))
Out[3]: 
array([[1, 2, 3, 1, 2, 3],
       [4, 5, 6, 4, 5, 6],
       [1, 2, 3, 1, 2, 3],
       [4, 5, 6, 4, 5, 6]])

In [4]: np.tile(np.tile(x, (2,2)), (1,3))
Out[4]: 
array([[1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3],
       [4, 5, 6, 4, 5, 6, 4, 5, 6, 4, 5, 6, 4, 5, 6, 4, 5, 6],
       [1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3],
       [4, 5, 6, 4, 5, 6, 4, 5, 6, 4, 5, 6, 4, 5, 6, 4, 5, 6]])

In [5]: np.tile(np.tile(x, (2,2)), (3,1))
Out[5]: 
array([[1, 2, 3, 1, 2, 3],
       [4, 5, 6, 4, 5, 6],
       [1, 2, 3, 1, 2, 3],
       [4, 5, 6, 4, 5, 6],
       [1, 2, 3, 1, 2, 3],
       [4, 5, 6, 4, 5, 6],
       [1, 2, 3, 1, 2, 3],
       [4, 5, 6, 4, 5, 6],
       [1, 2, 3, 1, 2, 3],
       [4, 5, 6, 4, 5, 6],
       [1, 2, 3, 1, 2, 3],
       [4, 5, 6, 4, 5, 6]])

In [6]: np.array([np.tile(x, (2,2)) for i in xrange(3)])
Out[6]: 
array([[[1, 2, 3, 1, 2, 3],
        [4, 5, 6, 4, 5, 6],
        [1, 2, 3, 1, 2, 3],
        [4, 5, 6, 4, 5, 6]],

       [[1, 2, 3, 1, 2, 3],
        [4, 5, 6, 4, 5, 6],
        [1, 2, 3, 1, 2, 3],
        [4, 5, 6, 4, 5, 6]],

       [[1, 2, 3, 1, 2, 3],
        [4, 5, 6, 4, 5, 6],
        [1, 2, 3, 1, 2, 3],
        [4, 5, 6, 4, 5, 6]]])

in MATLAB

>> repmat(x, [2,2,3])

ans(:,:,1) =

1     2     3     1     2     3
4     5     6     4     5     6
1     2     3     1     2     3
4     5     6     4     5     6


ans(:,:,2) =

1     2     3     1     2     3
4     5     6     4     5     6
1     2     3     1     2     3
4     5     6     4     5     6


ans(:,:,3) =

1     2     3     1     2     3
4     5     6     4     5     6
1     2     3     1     2     3
4     5     6     4     5     6

Eigenvalue solving by lobpcg in Python

Scipy provides two sets of functions for solving eigenvalue problems:

1. ARPACK-wrapped scipy.sparse.linalg.eigsh and scipy.sparse.linalg.eigs, and 
2. LOBPCG-based scipy.sparse.linalg.lobpcg. 

The latter is new to me. However I notice something interesting.

First, the option largest= seems to work in the opposite way. If I set is as largest=False, I actually get largest eigenvalues. To get smallest eigenvalues, I set it as largest=True.

Second, the function requires an initial approximation to the eigenvectors, which is not easy for new users. As someone pointed out, sometimes it takes "a very large number of iterations to get the correct eigenvalues."

Nevertheless, the solver is not too bad compared with ARPACK-wrapped eigsh (for real symmetric square matrix or complex hermitian matrixes) and eigs (for non-symmetric square matrixes). For example, given two matrixes, I got the two eigenvalues for general eigenvalue problem:

• by eigsh: [-1.0385276515935676e-16, 0.9194804029047039, 3.7579933101613547, 8.257545329015041, 10.44664798242384]
• by lobpcg: [7.0329601669327232e-16, 0.91948040290470379, 3.7579933101613623, 8.2575453290150449, 10.446647982423839]