Embedded Systems Designs

  SPI (Serial Peripheral Interface)  is a  synchronous  communication protocol that enables data transfer between microcontrollers and peripheral devices. It is a  full-duplex , master-slave protocol which means data can be sent and received simultaneously. When the master device sends data to the slave device, the slave device can send data back to the master device without waiting for a separate read operation. It is commonly used in embedded systems, especially in applications requiring high-speed data transfer. The SPI protocol requires four pins: MOSI  (Master Output Slave Input): The MOSI pin is used by the master device to transmit data to the slave device. MISO  (Master Input Slave Output): The MISO pin is used by the slave device to transmit data back to the master device. SCLK  (Serial Clock): The SCLK pin provides the clock signal used to synchronize the data transfer between the master and slave devices. CS  (Slave Select): The CS...

  UART (Universal Asynchronous Receiver/Transmitter)  is a communication protocol commonly used in microcontrollers and other embedded systems. It allows for serial communication, enabling the transfer of data between two or more devices. Two main components in UART are:  a transmitter  and  a receiver . The transmitter converts parallel data from a microcontroller or computer into a serial stream of bits, while the receiver converts the serial stream of bits back into parallel data. The data is transmitted in the form of packets called frames, which consist of a start bit, data bits, optional parity bit, and stop bits. UART Packet Format As mentioned above, UART communication involves transmitting data in the form of  frames , with each frame consisting of a start bit, data bits, optional parity bit, and stop bit. Details of the frame is as below: The Start Bit : The start bit is a logic low (0) signal that indicates the beginning of the data frame. It is ...

  In I2C communication , one device acts as the master and initiates the communication, while the other devices act as slaves and respond to the master’s commands. The master generates the clock signal and controls the data transfer, while the slaves respond to the commands sent by the master. Each device on the bus is identified by a unique 7-bit or 10-bit address, which is used by the master to address the slave device for data transfer. It also supports different data transfer formats such as byte mode, page mode, and sequential mode. The I2C protocol also includes error detection and correction mechanisms such as ACK/NACK signals and CRC checks to ensure reliable data transfer. In this post, Master-Slave code implementation is covered in detail. Image shared below is explaining the flow chart of the code. For each module explanation, please refer the link shared below: https://embeddedwala.com/Blogs/DigitalCommunication/Getting-Started-with-I2C:-Code-Example

  I2C (Inter-Integrated Circuit) is a widely used communication protocol for embedded systems. It enables communication between different components using a synchronous serial communication mechanism. One of its key features is arbitration, which resolves conflicts that occur when two or more devices try to transmit data at the same time. Arbitration in I2C is based on a wired-AND logic system, where devices on the bus can pull the bus lines low but not high. If two or more devices try to transmit data simultaneously, the device that pulls the bus lines low first wins the arbitration and can transmit its data. The other device backs off and waits for the next opportunity to transmit its data. For example, if two I2C Master devices are connected to the same bus and both attempt to transmit data to the same I2C Slave , an arbitration process will occur to determine which device has priority. The device that pulls the SDA line low first will win the arbitration and proceed to transm...

  I2C (Inter Integrated Circuit) is a communication protocol used in embedded systems to connect microcontrollers and other integrated circuits. In order to guarantee dependable communication among devices in I2C, hardware components like resistors and capacitors perform a critical role. The I2C protocol employs two signals — the data ( SDA ) and clock ( SCL ) lines — which are open-drain (or open-collector) pins. The pull-up resistors are required to maintain the high state of the data lines, and capacitors help to stabilize the voltage on the bus and filter out noise. The formula for calculating the pull-up resistor value is R = (Vcc — Voh) / Iol and the formula for calculating the maximum allowable bus capacitance is C = (Iol / (dV/dt)) * 1.2 Choosing appropriate values for resistors and capacitors is essential for reliable communication between devices. Excessive capacitance or low resistance can cause signal degradation and errors in communication. For more details, please r...

In  I2C(Inter-Integrated Circuit)   communication , the   master  device initiates the communication by sending a   start condition   and then sending the   slave device’s address . The slave device then responds with an   ACK   (acknowledge) signal to indicate that it has received the address correctly. If the slave device needs more time to process the data, it can hold the clock signal low to pause the communication temporarily. This is known as   clock stretching . Clock stretching is a technique used in communication protocols to allow slower devices to slow down the clock signal of a faster device. This technique is commonly used in I2C communication, where the clock stretching is performed by the slave device. This is useful in scenarios where multiple devices of different speeds are connected to the same bus. However, clock stretching can also cause  timing issues  if not implemented correctly. If the slave device holds...

    Getting Started with I2C I2C (Inter-Integrated Circuit) is a two-wire interface developed by Philips Semiconductors in the 1980s to connect low-speed devices such as sensors and microcontrollers. It uses a master-slave architecture, where the master controls communication between devices. The protocol uses only two signal lines, SDA (Serial Data) and SCL (Serial Clock), and a synchronous clock to synchronize communication between the devices. I2C communication is half-duplex , and pull-up resistors are required on both the SDA and SCL lines. I2C supports two addressing modes: 7-bit addressing and 10-bit addressing. In 7-bit addressing, each device is assigned a unique 7-bit address. In 10-bit addressing, each device is assigned a unique 10-bit address, and it is used when a large number of devices need to be connected to the I2C bus. I2C communication starts with a start condition, which is a high to low transition on the SDA line while the SCL line is high. After the sta...

  An interrupt is a signal that is sent to the processor to temporarily halt the execution of the current task and handle a higher-priority task. Interrupts are an important aspect of real-time embedded systems , where it is essential to respond to events quickly and efficiently. An interrupt controller is a hardware component that manages interrupts in an embedded system. There are many types of interrupt controllers depending upon the different configurations in the interrupt controller hardware. Below are the most common types of interrupt controllers: Generic Interrupt Controller (GIC): It is designed to be compatible with multiple processors or architectures. It provides a standard interface for handling interrupts, which allows it to be used with different types of processors without needing to modify the software. This makes it a flexible and cost-effective solution for embedded systems that use different processors or architectures. Nested Vector Interrupt Controller (N...

  In an Embedded System , a Microcontroller or Microprocessor uses the Input/Output pins to interact with the outer world and the other devices. Output pins take the data or information out and input pins to read the data or information. Software on the microprocessor runs at a very high speed than the hardware interactions. A few milliseconds of delay with the hardware could be thousands of instructions for the software. So for optimal hardware and software interaction, there is a mechanism called interrupts. An interrupt is a signal that temporarily halts the normal execution of a program and directs the MCU to execute a specific piece of code, called an interrupt handler or interrupt service routine (ISR) . Interrupts are typically triggered by external events, such as a button press, a sensor reading, or a timer expiration. Interrupt Sources can be classified into two main categories : Internal interrupt: sources are generated by the MCU itself, such as a timer overflow or...

DMA is a technique that allows data to be transferred between devices without the intervention of the CPU. In a typical computer system, data is transferred from one device to another via the CPU . The CPU initiates the transfer, reads data from one device, and writes it to another device. This process can be time-consuming and takes up valuable CPU time, which can slow down the system. It eliminates the need for the CPU to be involved in data transfer by allowing data to be transferred directly between devices. These controllers can be built into the devices or added as a separate component to the system. The DMA controller operates independently of the CPU and uses its own memory address and data buses to transfer data between devices. The DMA controller is programmed by the CPU to read data from one device and write it to another. The DMA controller can transfer data in blocks, making the process faster and more efficient. When the CPU needs to transfer data, it initiates the tran...

Start Up code of an MCU Starting up an MCU (Microcontroller Unit) involves executing a sequence of instructions that initializes the various on-chip peripherals and sets up the processor’s operating environment. This sequence of instructions is often referred to as the “startup code"  and is typically provided as part of the development tools provided by the chip manufacturer. The startup code is responsible for configuring several hardware and software aspects of the MCU to prepare it for the application code to run. Details of these tasks is as below: Stack Pointer Initialization : Stack Pointer points to the memory location in RAM which will be used by the program to store the function call stacks and the local variables for each function call. Data Section Initialization : Data Section in the memory layout contains the initialized global and static variables. Block Started by symbol (BSS) Initialization : BSS Section in the memory layout contains uninitialized global and sta...

  A boot sequence is a crucial part of any Microcontroller’s (MCU) operation. It is the process by which an MCU initializes and prepares itself for the main program’s execution. The boot sequence is essential because it sets up the system’s environment, initializes the necessary hardware and software components, and loads the main program into the MCU’s memory. In this article, we will explore the boot sequence of an MCU and understand the steps involved in its operation. Power-On Reset (POR): When an MCU receives power for the first time, a hardware-based reset called a Power-On Reset (POR) occurs. This resets all registers and memory to their default state. Check the Reset Vector: After the POR, the MCU checks the reset vector, which is a location in memory that contains the address of the first instruction to be executed. Initialize the Stack Pointer: The next step is to initialize the stack pointer, which is a register that keeps track of the program’s execution. The stack po...