Question

Please answer these questions clearly in hand written, thank you!

1. Explain 4 things you can do with a JTAG unit while debugging code.

2. The first time an optical shaft encoder was connected to a microprocessor the engineer used an external interrupt but with it configured as a level edge triggered interrupt. Explain why that was not a good idea

3. Discuss the differences between “bare metal” and a Linux operating system and give an example of when each is more appropriate.

Answer 1

May this helps you...

Answer 1:

1. JTAG is used in accessing sub-blocks of integrated circuits, thus, making it an important tool for debugging embedded systems that might not have any other debug-capable communications channel.
2. JTAG-based debugging is available in many systems from the very first instruction after the CPU is reset, letting it aids with the construction of early boot software which runs before the set up of anything.
3. JTAG is used by the JTAG adapter as the transport mechanism to obtain on-chip debug modules inside the destined CPU.
4. To debug software operating inside a CPU JTAG techniques are applied that can help debug other digital design blocks inside an FPGA.

Answer 2:

Encoder signals should be detected and interpreted within the software as fast as possible to not block the most process flow. we will detect the signals by polling within the main loop or using interrupts. Polling isn't an efficient way because you'll got to reserve time and resources in your main loop which can bring extra delays. Using interrupts may be a faster and cost-effective solution. we'll show you ways to use interrupts to handle the encoder signals.

There are two sorts of interrupts which will be used for this purpose; External Interrupt and Pin Change Interrupt. External Interrupt can detect whether the input is falling or rising and may be triggered in one among the chosen states which are: rising, falling, or toggling. There are more hardware resources for Pin Change Interrupt but it cannot detect the falling or the rising edge and it's triggered when any logical change occurs.

Answer 3:

Bare metal refers to run a program or software directly on the hardware level without the support of any OS .
In other words, program a microcontroller directly with a bunch of lines of C or Assembler-code, because it was traditionally made in electronics and that we learned it.
It is a low-level method of programming and it's specific to the hardware used.

Most of the bare-metal projects don't start from scratch (at all). it might cost tons to start out every project from zero again and again. We use instead some already tested libraries.

• Better execution with the same HW in bare metals
• They are easy and fast for small applications
• They are reliable.

• Complexity of the bare metal increase exponentially with the system size and functionalities
• in bare metal, basic and standard functions have to be programmed and adapted to the specific HW
• There is no multi-threading possibilities in one core

In embedded Linux, applications run over or supported by the kernel, acting as an OS . The "kernel" is that the nucleus or core of the OS controlling almost everything within the system.

Normal user-defined applications are called “User Space Applications” and that they have intermediate layers until they access the hardware. For that purpose, they have to travel through the kernel space to access to the HW. In Userspace is simply a piece of memory and over the kernel.

The bigger difference (and advantage) is that the userspace applications are hardware-independent.
The kernel of Linux consists of varied modules, which interact directly with the underlying hardware.

It provides the specified abstraction to cover low-level hardware details to system or application programs and thus made it hardware-independent.

• They are easily scalable
• They are portable
• linux supports multi-threading and priorities
• in Linux, free prebuilt drivers available that makes the development faster.
• There are less less bugs
• Linux is quite complex for small applications
• Steeper learning curve than bare metal

• Require a minimum (powerful) hardware to run the Kernel
• In Linux, security protection needed
• Updates of the system may be needed in linux