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8XC196Kx,8XC196Jx,87C196CA microcontroller family user's manual.1995.pdf
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ARCHITECTURAL OVERVIEW

Timer 1 and timer 2 are both 16-bit up/down timer/counters that can be clocked internally or externally. Each timer/counter is called a timer if it is clocked internally and a counter if it is clocked externally. (See Chapter 10, “Event Processor Array (EPA),” for additional information on the EPA and timer/counters.)

2.5.6Analog-to-digital Converter

The analog-to-digital (A/D) converter converts an analog input voltage to a digital equivalent. Resolution is either 8 or 10 bits; sample and convert times are programmable. Conversions can be performed on the analog ground and reference voltage, and the results can be used to calculate gain and zero-offset errors. The internal zero-offset compensation circuit enables automatic zerooffset adjustment. The A/D also has a threshold-detection mode, which can be used to generate an interrupt when a programmable threshold voltage is crossed in either direction. The A/D scan mode of the PTS facilitates automated A/D conversions and result storage.

The main components of the A/D converter are a sample-and-hold circuit and an 8-bit or 10-bit successive approximation analog-to-digital converter. See Chapter 11, “Analog-to-digital Converter,” for more information.

2.5.7Watchdog Timer

The watchdog timer is a 16-bit internal timer that resets the device if the software fails to operate properly. See Chapter 13, “Minimum Hardware Considerations,” for more information.

2.5.8CAN Serial Communications Controller (87C196CA Only)

The 87C196CA device has a peripheral not found on 8XC196Jx or 8XC196Kx devices, the CAN (controller area network) peripheral. The CAN serial communications controller manages communications between multiple network nodes. This integrated peripheral is similar to Intel’s standalone 82527 CAN serial communications controller, supporting both the standard and extended message frames specified by the CAN 2.0 protocol parts A and B. See Chapter 12, “CAN Serial Communications Controller,” for more information.

2.6SPECIAL OPERATING MODES

In addition to the normal execution mode, the device operates in several special-purpose modes. Idle and powerdown modes conserve power when the device is inactive. On-circuit emulation (ONCE) mode electrically isolates the microcontroller from the system, and several other modes provide programming options for nonvolatile memory. See Chapter 14, “Special Operating Modes,” for more information about idle, powerdown, and ONCE modes and Chapter 16, “Programming the Nonvolatile Memory,” for details about programming options.

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8XC196Kx, Jx, CA USER’S MANUAL

2.6.1Reducing Power Consumption

In idle mode, the CPU stops executing instructions, but the peripheral clocks remain active. Power consumption drops to about 40% of normal execution mode consumption. Either a hardware reset or any enabled interrupt source will bring the device out of idle mode.

In powerdown mode, all internal clocks are frozen at logic state zero and the oscillator is shut off. The register file, internal code and data RAM, and most peripherals retain their data if VCC is maintained. Power consumption drops into the µW range.

2.6.2Testing the Printed Circuit Board

The on-circuit emulation (ONCE) mode electrically isolates the 8XC196 device from the system. By invoking ONCE mode, you can test the printed circuit board while the device is soldered onto the board.

2.6.3Programming the Nonvolatile Memory

MCS 96 microcontrollers that have internal OTPROM or EPROM provide several programming options:

Slave programming allows a master EPROM programmer to program and verify one or more slave MCS 96 microcontrollers. Programming vendors and Intel distributors typically use this mode to program a large number of microcontrollers with a customer’s code and data.

Auto programming allows an MCS 96 microcontroller to program itself with code and data located in an external memory device. Customers typically use this low-cost method to program a small number of microcontrollers after development and testing are complete.

Serial port programming allows you to download code and data (usually from a personal computer or workstation) to an MCS 96 microcontroller asynchronously through the serial I/O port’s RXD and TXD pins. Customers typically use this mode to download large sections of code to the microcontroller during software development and testing.

Run-time programming allows you to program individual nonvolatile memory locations during normal code execution, under complete software control. Customers typically use this mode to download a small amount of information to the microcontroller after the rest of the array has been programmed. For example, you might use run-time programming to download a unique identification number to a security device.

ROM dump mode allows you to dump the contents of the device’s nonvolatile memory to a tester or to a memory device (such as flash memory or RAM).

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