Embedded System Timers: Hardware vs Software

Hardware timers are used for timing and counting operations, allowing the processor to carry on with some other process while the timer process runs Software Timer allows you to execute a function sometime in the future. To make use of this feature, you will need to: Create a software timer. Define the software timer's callback function 2 Structure of Hardware Timer -______ -count-up timer counts up from a past event, say, an important event of your systemic-life. -countdown timer is a virtual clock on a landing page that counts down from a certain number or date to indicate the beginning or end of an event or offer. 3 Usage of TIMERS 1 Real Time Clock (RTC) for the system 2 Initiating an Event after a preset time delay 3 Initiating an Event after a comparison of preset times 4 Capturing the count value in timer on an event 5 Finding time interval between two events 6 Watchdog timer 7 Baud/telecommunication rate control for Serial communication 8 Scheduling of various tasks in RTOS 9 Time slicing of various tasks 10 Time division multiplexing 13/4/2009 4 Programming Embedded Systems in Assy & C Assembly C, C++ 1. Full use of processor specific instructions. 1.

The rate can be set to several possible values. The exact values depend on the chip; -______ counts up from a past event, say, an important event of your systemic-life. -countdown timer is a virtual clock on a landing page that counts down from a certain number or date to indicate the beginning or end of an event or offer. 3

The rate can be set to several possible values. The exact values depend on the chip; -count-up timer counts up from a past event, say, an important event of your systemic-life. -______ is a virtual clock on a landing page that counts down from a certain number or date to indicate the beginning or end of an event or offer. 3

Usage of TIMERS 1 Real Time Clock (RTC) for the system 2 Initiating an Event after a preset time delay 3 Initiating an Event after a comparison of preset times 4 Capturing the count value in timer on an event 5 Finding time interval between two events 6 ______ 7 Baud/telecommunication rate control for Serial communication 8 Scheduling of various tasks in RTOS 9 Time slicing of various tasks 10 Time division multiplexing 13/4/2009 4

Programming Embedded Systems in Assy & C ______ C, C++ 1. Full use of processor specific instructions. 1.

The rate can be set to several possible values. The exact values depend on the chip; -______ counts up from a past event, say, an important event of your systemic-life. -countdown timer is a virtual clock on a landing page that counts down from a certain number or date to indicate the beginning or end of an event or offer. 3

______ is a virtual clock on a landing page that counts down from a certain number or date to indicate the beginning or end of an event or offer. 3

Usage of TIMERS 1 Real Time Clock (RTC) for the system 2 Initiating an Event after a preset time delay 3 Initiating an Event after a comparison of preset times 4 Capturing the count value in timer on an event 5 Finding time interval between two events 6 ______ 7 Baud/telecommunication rate control for Serial communication 8 Scheduling of various tasks in RTOS 9 Time slicing of various tasks 10 Time division multiplexing 13/4/2009 4

Types of I/O Devices - Device I/O Types and Examples – Synchronous - Isosynchronous – Asynchronous Communications from Serial Devices - Examples of Internal Serial-Communication – Devices - UART and HDLC – – Parallel Port Devices – Timer and Counting Devices ‗USB  advanced I/O Serial high speed buses- ISA, PCI, PCI-X, cPCI and advanced buses.

In UART communication, two UARTs communicate directly with each other. Only two wires are needed to transmit data between two UARTs. Data flows from the Tx pin of the transmitting UART to the Rx pin of the receiving. --Full Duplex mode --Peer to Peer --Used to: 1-Make a communication channel between our microcontroller and our computer. 2-talk to most sensors or chips , the most used ones are serial backpacks for lcd’s and GPS modules that almost always have a serial interface.

HDLC (High-level Data Link Control) is a group of protocols or rules for transmitting data between board points In HDLC, data is organized into a unit (called a frame) and sent across a network to a destination that verifies its successful arrival.

Structure of Hardware Timer -The pre-scaler splits the clock signals used for the timer, reducing overflow rates. The rate can be set to several possible values. The exact values depend on the chip; -count-up timer counts up from a past event, say, an important event of your systemic-life. -countdown timer is a virtual clock on a landing page that counts down from a certain number or date to indicate the beginning or end of an event or offer.

Hardware timers are used for timing and counting operations, allowing the processor to carry on with some other process while the timer process runs Software Timer allows you to execute a function sometime in the future. To make use of this feature, you will need to: Create a software timer. Define the software timer's callback function 2 Structure of Hardware Timer -______ -count-up timer counts up from a past event, say, an important event of your systemic-life. -countdown timer is a virtual clock on a landing page that counts down from a certain number or date to indicate the beginning or end of an event or offer.