PIC n’Mix
Mike Hibbett’s column for PIC project enlightenment and related topics
Part 2: Software tools for the PIC18F
S
eptember 2020 marks the 15th anniversary
of my start as a writer for the magazine. Back in 2005,
articles were submitted by paper copy months in advance, followed by many iterations, all requiring that alterations
still fitted within the same layout. ‘If you take five letters out,
add five letters in’ was standard practice. 15 years later we
rework articles through email but there are still many iterations to create our published output. In 15 years, editorial
processes have changed, but I still recognise and remember
the magazine I read as a child in the 1970s, and the authors
who I was fortunate enough to work with since becoming an
author. It’s with great fondness I remember John Becker, my
former technical editor, who was both my professional liaison
with the magazine and my hero from the 1970s.
Tools for the job
So, onto this month’s article, where we look at the software tools
available for developing programs on Microchip PIC processors.
In the July issue we covered how we selected the PIC18F47K42
(in a 40-pin DIL package) to form the basis of our PIC18 ‘Experimenter’ board. We chose the PIC18F47K42 through a long
selection process – there are around 17,000 Microchip processors
to choose from – because it offers a broad range of peripherals,
in an easy-to-work-with package. It has not been used in projects
within the magazine before, which makes it an interesting candidate. There has been no particular reason why it has not been
used before – authors tend to stick with older processors they
are familiar with – but the PIC18F47K42 offers a wide range of
peripherals and lots of memory, which will make it adaptable
for many different projects.
Before we delve into the hardware aspects of any designs
based on this processor, we need to get the software development
environment installed, and a level of familiarity established.
This is true whether you are a hobbyist or a professional
Fig.1. Microchip debuggers (l-r): PICit 4, Snap, PICkit 3. We
strongly recommend the PICkit 4, but the PICkit 3 is also a good
choice. The Snap, however, is too limited for this project series.
Practical Electronics | September | 2020
developer; having a complete development environment and
being comfortable using it can make a huge difference to how
easy it is to build a project, quickly.
PIC vs Arduino
Developing software for the PIC processor is very different
to platforms such as the Arduino, which comes with over a
hundred libraries and example applications. Microchip focus
on providing a few key low-level driver libraries, and just a
handful of example applications. Their low-level documentation for the processor is excellent however, so writing any
new driver libraries is possible, and allows you to fine tune
your software to match your application’s needs, and the capabilities of the processor. It does, however, require that you
understand more about what is going inside the processor.
That’s fine – it’s the reason why we experiment with PIC processors, to learn more about what is going on. If this learning
opportunity does not interest you and you only want to get a
project up and running as quickly as possible, then an Arduino
development system would be more appropriate. The benefit of
learning more about the processor itself is that it will provide
you with many more options to solving a design challenge,
and with more complex designs, enable you to create a solution that would not be possible on a simple Arduino platform.
MPLAB X IDE
Developing software requires a number of different tools. At a
minimum, you need the following:
Text editor
Compiler
Driver libraries
Programmer/debugger
Programming interface
To pull all these requirements together Microchip have created an Integrated Development Environment (IDE) called
MPLAB X, which combines the code editor, programmer and
debugger capabilities into a single application. The IDE is
really a framework application that allows other PC programs
to be configured, run and the results viewed all within the
same application. It’s possible to run the compiler, see a list
of error messages from that complier in an IDE window, that
when you click the mouse on them will cause the offending
line of code to come up in the editor window. Using MPLAB
X is not a hard-and-fast requirement; you could edit your
programs using your favourite editor, then compile the program in a command shell. However, Microchip’s IDE simply
makes the process easier and quicker to perform.
In addition to MPLAB X we will also need a compiler. This
is a standalone application that will convert our programs,
written in text files in the ‘C’ programming language, into the
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compiler performs to reduce code size. This would be important
if you were building a large number of products and would like
to use smaller, cheaper versions of a microcontroller. For hobbyists, we can simply purchase the device with larger memory
that costs perhaps 50p more. To reiterate, you are not missing
out on features by avoiding an expensive purchase.
Programming interface
Fig.2. Uninstalling
MPLAB components.
binary format that the processor understands. Microchip provide three different compilers for the different PIC families:
MPLAB XC8: all 8-bit PIC devices, from the PIC10F to the
largest PIC18F
MPLAB XC16: all 16-bit PIC devices, PIC24, dsPIC33
MPLAB XC32: all 32-bit PIC devices, such as the PIC32
These have to be download separately to MPLAB X but are
very easy to install.
The programmer and debugger capabilities are pre-built into
MPLAB X and do not require a separate download.
With the above components you have the minimum software
necessary to start developing programs. However, one further
download provides a set of goodies – example drivers and
sample applications – that will make our life easier, especially
if we are using UART, I2C or SPI communications. Confusingly,
Microchip provide three different software packs to fulfil this,
called MLA, Harmony and MCC.
MLA is the old and now deprecated ‘Microchip Libraries
for Applications’, which has been replaced by MCC, ‘Microchip Code Configurator’. MCC is used with 8-bit devices, such
as the PIC18F family. Harmony is a similar pack of libraries,
but targeted to 32-bit devices, so of no interest to us today. We
will be installing MCC and will be making frequent use of it.
In summary, our installation process will be MPLAB X, the
XC8 compiler, followed by MCC. If you plan to use a 16-bit
or 32-bit processor in the future, feel free to install those two
compilers too, as they can co-exist with no issue. MPLAB X
is smart enough to choose the correct compiler for your project, as we will show later.
Last, but not least, Microchip have helpfully made these tools
available not only for Windows, but also Linux and macOS PCs.
…and the cost?
The great news is that the MPLAB X IDE and the MCC libraries
are free – however, the situation is a little more complicated with
the compiler programs. They are provided for free, but you can
pay to unlock commercial/professional features. The professional
versions provide additional optimisations in the translation to
a code binary, and this can result in a 20-30% improvement in
code space use compared to the ‘free’ version of the compiler.
There may also be some reductions in the amount of RAM used.
In our opinion, for hobbyists, these improvements do not justify
a fairly expensive purchase of a professional compiler licence.
The ‘free’ version is not crippled in any way; all compiler features are available – the difference is in the optimisations the
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Microchip processors require a small piece of hardware, called
a ‘debugger’, to transfer programs to a device. The tool of choice
is the PICkit 4 from Microchip, which costs around £55. The
previous generation debugger, the PICkit 3, can also support
the processor we are using and is cheap secondhand on eBay
(from £12). Clones of the PICkit 3 can be purchased on eBay for
as little as £15, but we strongly recommend using the official
device. We will focus on using the PICkit 4 in this and future
articles. It’s a solid product that should last for years – we have
never had a Microchip debugger fail on us in 25 years, the only
issue is that every decade or so new processors become available
that require a programmer update, but you will be required to
update your programmer only if you want to use those new ICs.
There is a lower-cost debugger available from Microchip
called the ‘Snap’, which costs around £18. It can program the
PIC18F47K42 but has limited features, comes as just a bare
PCB and in our opinion is just too basic for our plans. You
can see these three debuggers in Fig.1.
On a historical note, our first emulator for the PIC16 series
of processors cost around £900 back in 1995!
The debugger is connected to the PC via a USB cable (supplied with the debugger.) Five signals connect the debugger
to your target PCB via an 8 pin 0.1-inch pitch header socket.
Hook-up wires can be used to make the connection, but we
prefer to fit an 8-pin header strip to our boards and plug the
debugger in directly – we will provide an 8-pin header strip
on our experimenter board.
Installation preparation
In the following sections we describe the setup for PCs running the Windows OS, as this is the most common setup. The
installation process for other operating systems will be similar – check online for exact details if you are using Linux or
macOS operating systems.
Before we install the latest versions of the software (Microchip update their software tools frequently) we will want
to remove any previous versions. Your creations will not be
deleted by these steps, just the very large IDE and compiler install files, which can add up to many gigabytes of disk space.
If you do not have Microchip tools installed you can skip to
the ‘Installation’ section below.
To remove earlier versions, first click on the ‘Start’ button,
then type ‘Add’, and select ‘Add or Remove programs’. From
the drop-down list that appears, as shown in Fig.2, type ‘mplab’
in the search box to filter just the Microchip software components. Now remove all ‘Microchip’ installed features. You
will have to do these one at a time. Left click on an item in the
list, then click the ‘Uninstall’ button. Follow the instructions,
and when done, repeat for all the other entries. We had about
a dozen entries for multiple old versions of the toolchain, so
this bit of spring-cleaning freed up over 10GB of disk space.
Installation
We start by installing the latest version of MPLAB X IDE, which
at the time of writing is version v5.40. In your browser, go to:
https://www.microchip.com/mplab/mplab-x-ide and scroll down
to the ‘Downloads’ tab. Click on the text ‘MPLAB X IDE v5.40’
to start the download. Don’t worry if the version has been updated, changes are likely to be minimal. Microchip make regular
updates to their software tools (typically when new processors
Practical Electronics | September | 2020
Adding MCC
Fig.3. The MPLAB X main window.
Our final installation step is to bring in MCC – the drivers that
we can add to our projects. MCC is not just a set of source
files, it’s a complete GUI (graphical user interface) that helps
simplify the process. Confusingly, there are several ways to
install MCC; we will do it within MPLAB X itself, as the IDE
has a ‘plug-in’ tool already built in.
Click on the ‘Tools’ menu option, followed by ‘Plugins’ (not
‘Plugins Download).
Click on ‘Available Plugins’ and scroll down until you see
‘MPLAB Code Configurator’. Click the check-box, then click
on the ‘Install’ icon at the bottom of the window, as shown
in Fig.4. Click ‘Next’, then accept the licence agreement, and
click ‘Next’ to start the installation process. MPLAB X will
now download MCC and install it; so this may take a minute
or two. At the end, MPLAB X will need to restart, so just click
‘Finish’. MPLAB X will restart automatically after a few seconds and complete the installation process. We are now ready
to create our first project.
If you have a PICkit 4 debugger, go ahead and plug that in now.
The front of the device should illuminate blue once connected.
In MPLAB X IDE, click on the ‘File’ menu option, followed
by ‘New Project...’. In the ‘Categories’ section of the pop-up
window leave ‘Microchip Embedded’ highlighted and click
on ‘Standalone Project’ followed by ‘Next’. In the highlighted
‘Device:’ field, type in the name of our processor, ‘PIC18F47K42’.
If you have a PICkit 4 plugged in then select it from the ‘Tool:’
drop-down list. Click ‘Next’. We can select the compiler we
will be using; XC8. This should be shown in this list, so click
on that and then click ‘Next’.
Finally, we have to give our project a name (type ‘test’) and
specify where this project will live on your PC’s disk. This directory will hold your project settings and all the source files
you create. For now, it is an empty project and we shall leave
MPLAB X at this point and return to it once we have completed our hardware design.
are added, but also for bug fixes and improvements.) MPLAB
has been in development and maintained for many years.
Once downloaded, double click the file to start the installation process. Other than clicking to accept the software
licence terms, accept all defaults. We recommend that you do
not change the installation folder as this will make installing
the compiler and MCC libraries difficult.
Close to the end of installation a Windows Security pop-up
will be displayed. Click ‘Install’ to install the hardware drivers
for the debugger tool. At the end of installation, a Setup pop-up
appears; untick the three checkboxes – we will perform these
steps manually. Click ‘Finish’ to complete the installation.
Now for the compiler; in your browser, go to: https://www.
microchip.com/mplab/compilers. and scroll down until you
see the ‘Compiler Downloads’ tab. Click on that, and then
click on ‘MPLAB® XC8 Compiler v2.20’. Again, this version
may have been updated by the time you get to it, so it may be
v2.21 or similar. This is fine; compiler updates rarely impact
Coming up next
users of the tool, and just provide minor bug fixes. Again, once
In the next article we will start the design of our experimentdownloaded, double-click on the file to start installation. Other
er PCB. Our intent is to make clear the thought process going
than clicking to accept the software licence terms, accept all
into the design of the board and explore the capabilities of the
defaults. The installation process will update MPLAB so that
processor. We will be focusing on using the processor rather
it ‘knows’ a compiler has been installed.
than diving into the details of internal processor peripherals.
We can now start MPLAB X IDE by double-clicking on the
We are going to cover: GPS location reporting, digital compass,
newly created desktop icon, or by clicking on the Windows
various display technologies, speech output, PC connection via
‘Start’ icon and typing ‘mplab x’. Be careful at this point – the
USB, Wi-Fi communication, interfacing with Amazon Alexa,
MPLAB X IDE installation process installs another useful appliServo motor control, analogue input.
cation, a programmer utility, that is amusingly called MPLAB
Some are more ambitious than others, but it will be a fun
X IPE. Given this differs by only a few pixels on the screen,
journey and we hope you will join in. The PCB will be availit’s easy to click on the wrong one. We ended up deleting the
able from our usual suppliers, and full PCB Gerber and design
desktop icon for IPE by right-clicking on the desktop icon and
files available should you wish to etch your own, although as
selecting ‘Delete’. This removes the short-cut icon from the
a double-sided design this might be challenging.
desktop, but leaves the program installed and ready to
launch from the Windows Start menu.
If you’ve previously installed MPLAB you will be presented with a pop-up box asking whether you would like
to import old settings from the previous installation. We
recommend you do not do this – we want to start with a
clean sheet. So click ‘No’ if presented with that message.
You may get a warning from your virus protection software that mplab_ide64.exe is attempting to access the
network. Go ahead and click ‘Allow access’, as we trust
Microchip, and this feature enables MPLAB to check for
updates to software automatically.
You should now see the main IDE window, as shown in
Fig.3. Two windows are opened on start-up, ‘Start Page’
and ‘MPLAB X Store’. Go ahead and close these windows by clicking the ‘x’ on the right-hand side of the tabs. Fig.4. MCC installation via MPLAB X.
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