In this video, we'll look at the manufacturer and third party hardware development kits and the important documentation that is needed to configure your microcontroller. Development kits are an important tool for software engineers to start becoming familiar with an architecture. Designing hardware takes a lot of experience and you hope your platform has no hardware bugs that stall your software progress. By using evaluation kits, you have a pretty generic hardware platform with lots of vendor support for you to get your software design started. Most projects begin by using developers kit to evaluate platform options. There are many manufacturers of microcontroller integrated circuits, ICs, or application-specific integrated circuits, ASICs, in the industry. Some examples include Texas Instruments, Silicon Labs, Atmel, or NXP Semi-conductors. The silicon manufacturers often make many different type of chips with an assortment of features, and they sell their chips for a variety of vendors. Knowing how to pick a particular chip is difficult because there are particular factors you need to investigate before committing a product to a particular chip choice. Inside the IC, there's also a chance that different parts of silicon were built by different people. ARM is a good example, as they build CPU cores and other technology for silicon manufacturers. Microcontrollers have many features that you need to know about before making a selection, especially because there will be software implications. Some important features include the word size, the number of registers, flash and RAM sizes, branch prediction support, instruction and data cache support, floating point arithmetic support, or DMA support. These features affect the operation and performance on embedded platform. For instance, as you design your project, you will have to answer questions such as, how much memory will I need for my application? How fast does my application need to run? And what kind of mathematical support do I need? You likely need to have some of these answers before you commit to a particular microcontroller. The process of creating this feature and operation requirements checklist is called a specification, or a features spec. It's possible that you need to make significant software changes, or even a hardware change, in the middle of a design process if you did not evaluate your initial designs correctly. In general, you do not select a chip or a part at random. There is some investigation of features and specs needed at the beginning of a project, which includes some prototyping and proof of concept. Fortunately, manufacturers help with this process by providing resources to analyze their products. There are many documents that describe how to pick out a platform or evaluate a particular chip. We start with discussing the Selector Guide. This helps a user slip down choices by interactively selecting feature sets for our design. It shows a full processor family. A chip family will share the same chip architecture. Each sub-family typically has more differences in supported hardware. And each device in a sub-family only has a slightly variances from one sub-family part to another. This guide example is somewhat of a painful chart to look at to select the part. However, this guide usually has a web-based interface which makes it much easier to search through. If you find some interesting parts from the selector guide, you can obtain some more information using the product brief. This gives a concise overview for quick evaluation of a platform for design, but more details than what you will see in the selector guide. This is much more marketed, and is far less dense than strict product specifications. Once you have slimmed down your selections to a subset of models, you can start getting into much more detailed documentation sources like the datasheet. This document gives technical specifications on a chip or a family of chips with a breakdown of all the differences between each version or part number within the family. Pin counts as well as operation specifications are provided with diagrams, tables and plots. These operation specifications can include many things. Electrical characteristics such as voltage and current operating ratings, where we get information on power specs of various conditions and operating modes. Timing characteristics are provided for our operation of the microcontroller. You will find info on the limit of the processor's clock frequencies. There are timing diagrams that show expected time delays before certain digital signals are asserted. These quantities are usually measured in micro or nano seconds. The datasheet even includes some extra data on how environmental effects, such as temperature, can affect the device or the operation characteristics. Lastly, you will also find physical design constraints, such as a CAD drawing with dimensions for the physical package and footprints of the chip. The materials in the datasheet is not just for a hardware engineer to use. Timing characteristics are very important for a software engineer to know about so they may predict or calculate runtime requirements and performance. In addition, the datasheet is going to detail the pinpoint mappings for a peripheral device you might use. This is a table that describes which pins match up to the general IO ports of the microcontroller, and subsequently, which pins can connect to certain peripheral devices. The datasheet does not typically provide information on configuration. For that, we need to look at the Family Technical Reference Manual. This manual describes information on general platform components and configuration. You may then have a sub-family reference manual which covers particular settings of a specific device. These are manuals that you need to look up to know how you go about configuring a chip using Bare-Metal Firmware. Sometimes the Family Technical Manuals are missing information or issues are found with the chip after the release of the product. This is called the Chip Errata. This is a document that contains additional and corrective information for our particular device set. It will list problems with the description of the configuration or the hardware's operation. They usually provide a workaround in the errata sheet. It is important that if something is operating unexpectedly with your chips that you consult the errata. Now that a chip has been chosen, we need to start on a proof of concept and software prototyping. Not all customers have the time or ability to design a printed circuit board or a evaluate their chosen chips and design. Many businesses just create development kits and module boards so that prototyping can be be done easily, speeding up the time it takes chip manufacturers to get their products in customer hands for evaluation. Here we have two example development kits. The first is a microcontroller development kit called the Freedom FRDM-KL25Z. This board is a product of NXP and has many impressive features including some supplemental external hardware, a capacitive touch slide, an RGB LED, and an accelerometer. These are purposely added so that some simple applications can be developed with external hardware as part of the evaluation process for the microcontroller. A second example is the wireless module featuring the Nordic nRF24L01 chip. This is not a microcontroller development kit. Development kits are not limited to microcontroller silicon manufacturers since any type of sensor, external memory, driver or communication device would want to be evaluated. The part is a difficult package to solder called a QFN package. And that may have specific requirements for its antenna. However, the board is built in a way that it can easily connect through microcontroller boards using a few extra wires. As an embedded software engineer, you can easily acquire many of these module boards or microcontroller development kits without deep hardware knowledge. Although you will need to figure out the connection and interface requirements between your boards. Now having access to a platform, you can start developing a software proof of concept without any hardware design overhead. Once a chip and development kit has been acquired, you need to get access to a compiler, some programmer debugger hardware and the executable installer software. The design of these support systems, dev kits, debuggers, programmers and software, are often done by applications and tool engineers from the chip manufacturer companies or third party vendors. But these kits, extra hardware and software tools often come at an expensive price from the manufacturer. Competition in this market of dev kits has grown significantly with the need for even faster prototyping. As a result, four dev kits have become even more widely available at a cheap price with free software tools and integrated programmer debugger hardware on the kit itself. Take, for example, the Freedom Board. This board has a secondary processor which is used to run as an onboard program debugger adaptor that can flash our target processor, the KL25Z. This adaptor is called OpenSDA. The OpenSDA has a specialized, dedicated connection to the processor target for debug support and for the programmer interface. The user will connect to this open SDA platform by connecting a USB cable to the host machine and running a special integrated development environment for this processor. Other manufactures have done similar things. That could be an example of Texas Instruments. Here is an MSP432 launch pad that houses the MSP432 Core text in. It comes with a dedicated onboard emulator for programming, debugging, and energy measurements. Texas Instruments calls their technology the XDS110 EnergyTrace on-board emulator. This EnergyTrace technology is an added system to evaluate energy uses of the target processor during application. This is in addition to debugging and installing. These onboard programmer debuggers provide much cheaper options for the software development tool sets you can use to interact with the desired embedded platform. In this video we learned about the importance of development kits and the documentation for designing an embedded system. Documentation will provide you architecture-specific information to configure your platform. And the kit will provide you early software prototyping and build your confidence in working with the hardware. With access to these items, you can evaluate many different processors to see if they meet your project's needs.
