TIMERS AND COUNTERS:TIMER OPERATION CONfiRMATION

By -

TIMER OPERATION CONfiRMATION

To make sure a timer is working, set up a program in which the interrupt routine incre- ments a variable and the main loop displays it. If you see the variable incrementing, the interrupt routine is working.

The speed of the incrementing will give you some idea of the rate at which the interrupts are occurring and will confirm that the interrupts are occurring as fast as you have programmed them to.

Other timer related registers can also be looked at to see what is going on in them by displaying them on the LCD.

Caution Writing to the LCD is time consuming and will slow down the system.

Comments

Post a Comment

Popular posts from this blog

80386 pins and signals , 80386 modes , 80386 system design and 80386 i/o

By -
Image
11.3.5 80386 Pins and Signals The 80386 contains 132 pins in Pin Grid Array (PGA) or other packages. Figure 11.2 shows functional grouping of the 80386 pins. A brief description of the 80386 pins and signals is provided in the following. The # symbol at the end of the signal name or the- symbol above a signal name indicates the active or asserted state when it is low. When the symbol # is absent after the signal name or the symbol- is absent above a signal name, the signal is asserted when high. The 80386 has 20 Vcc and 21 GND pins for power distribution. These multiple power and ground pins reduce noise. Preferably, the circuit board should contain VCC and GND planes. CLK2 pin provides the basic timing for the 80386. This clock is then divided by 2 by the 80386 internally to provide the clock used for instruction execution. The 80386 is reset by activating the RESET pin for at least 15 CLK2 periods. The RESET signal is level­ sensitive. When the RESET pin is asserted, the 8038...
Read more

Multi-Tasking and Real-Time Operating Systems:Random Number Generator

By -
Image
PROJECT 10.2—Random Number Generator In this slightly more complex RTOS project, a random number between 0 and 255 is generated. Eight LEDs are connected to PORTB of a PIC18F452 microcontroller. In addition, a push-button switch is connected to bit 0 of PORTD (RD0), and an LED is connected to bit 7 of PORTD (RD7). Three tasks are used in this project: Live, Generator, and Display. • Task Live runs every 200ms and flashes the LED on port pin RD7 to indicate that the system is working. • Task Generator increments a variable from 0 to 255 continuously and checks the status of the push-button switch. When the push-button switch is pressed, the value of the current count is sent to task Display using a messaging queue. • Task Display reads the number from the message queue and sends the received byte to the LEDs connected to PORTB. Thus, the LEDs display a random pattern every time the push button is pressed. Figure 10.9 shows the project’s block diagram. The circuit diagram is ...
Read more

Advanced PIC18 Projects—SD Card Projects:Using the Card Filing System

By -
Image
PROJECT 7.3—Using the Card Filing System The hardware of this project is the same as for Project 7.1 (i.e., as shown in Figure 7.8). In this project, a file called MYFILE55.TXT is created on the SD card. String “This is MYFILE.TXT” is written to the file initially. Then the string “This is the added data.. .” is appended to the file. The program then reads the contents of the file and sends the string “This is MYFILE.TXT. This is the added data.. .” to the UART, enabling the data to be displayed on the PC screen when HyperTerminal is run. The program listing of the project is given in Figure 7.12 (program SD3.C). At the beginning of the program the UART is initialized to 2400 baud. Then the SPI bus and the FAT file system are initialized as required by the library. The program then creates file MYFILE55.TXT by calling library function Mmc_Fat_Assign with the arguments as the filename and the creation flag 0x80, which tells the function to create a new file if the file doe...
Read more