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Test Program The test program LPC1 (Program 7.1) exercises the analogue input and LEDs, and is used to explain the testing and downloading processes. Its function is to rotate an LED through the bits of port B, with the speed controlled by the pot. The test program has the following structure: In the processor configuration […]
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PIC 16F690 Chip The data sheet for this chip should be downloaded from www.microchip.com and studied in conjunction with this section. The pin-out can be seen in the schematic Figure 7.3; it has only 20 pins in total, hence the ‘low pin count’ description. The 16F690 is representative of the 16 series chips as it […]
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Data Table A program may be required to output a set of predefined data bytes, for example, the codes to light up a seven-segment display with the correct pattern for each display digit. The data set can be written into the program as a table within a subroutine, and the data list accessed using CALL […]
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PICkit2 Demo System The PICkit2 is an in-circuit programming module that supports a full range of PIC microcontrollers. PICkit3 is now available. The PICkit2 Starter Kit also includes the LPC board incorporating the 16F690 MCU and some minimal test circuitry (Figure 7.2). The programmer is connected to the USB port of the host PC running […]
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In-Circuit Programming MPLAB IDE and a hardware programmer are the essential components of the Microchip toolset. Originally, PIC® chips had to be removed from the circuit for programming in a separate module, and then replaced in the target application board. Now, in-circuit programming allows the chip to be programmed without being removed, which avoids possible […]
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Serial Ports Serial communication ports allow the PIC to communicate with other MCUs, or exchange data with a master controller, via a single connection. Serial connections may also be made with external memory devices and sensors. There are several protocols available in PICs: • USART (universal synchronous asynchronous receiver transmitter) • SPI (serial peripheral interface) […]
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Peripheral Interfaces In the block diagram of each chip, the peripherals are shown as separate blocks attached to the internal data bus. These provide additional features such as timers, analogue inputs and serial ports. These are set up for use by initializing the related SFRs. The appropriate combination of peripherals is a major factor in […]
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Power Consumption Power consumption is generally proportional to clock speed in complementary metal oxide semiconductor (CMOS) devices, since most of the power is consumed when the transistors switch on and off. This is illustrated by the current consumption curve for a typical device, shown in Figure 12.2. For external crystal operation at clock frequencies between […]
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Input/Output Pins The number and type of inputs and outputs required needs to be considered at an early stage in circuit design. The convenient grouping of the pins for particular interfaces may also be relevant, with many chips having partial port implementations. For example, a 4-bit port can be conveniently used for a 4-bit input […]
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Device Selection Each type of PIC microcontroller offers a different combination of features; the most suitable can be selected for any given application. The range is expanding all the time, with additional features and improved performance at lower cost. Tables of MCU families at www.microchip.com allow the current features and price of each to be […]
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