DS89C430 datasheet(43/48 Pages) DALLAS

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DS89C430/DS89C440/DS89C450 Ultra-High-Speed Flash Microcontrollers

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Stop Mode

Stop mode disables all circuits within the processor. All on-chip clocks, timers, and serial port communication are

stopped, and no processing is possible.

Stop mode is invoked by setting the stop bit (PCON.1) to logic 1. The processor enters stop mode on the

instruction that sets the bit. The processor can exit stop mode by using any of the six external interrupts that are

enabled.

An external reset through the RST pin unconditionally exits the processor from stop mode. If the BGS bit is set to

logic 1, the bandgap provides a reset while in stop mode if VCC should drop below the VRST level. If BGS is 0, no

reset is generated if VCC drops below VRST.

When the stop mode is removed, the processor waits for 65,536 clock cycles for the internal flash memory to warm

up before starting normal execution. Also, the processor waits for the crystal warmup period if it is not using the

ring oscillator.

Serial I/O

The microcontroller provides a serial port (UART) that is identical to the 80C52. In addition, it includes a second

hardware serial port that is a full duplicate of the standard one. This port optionally uses pins P1.2 (RXD1) and

P1.3 (TXD1) and has duplicate control functions included in new SFR locations.

Both ports can operate simultaneously but can be at different baud rates or modes. The second serial port has

similar control registers (SCON1 at C0h, SBUF1 at C1h) to the original. The new serial port can only use timer 1 for

timer-generated baud rates.

Control for serial port 0 is provided by the SCON0 register, while its I/O buffer is SBUF0. The registers SCON1 and

SBUF1 provide the same functions for the second serial port. A full description of the use and operation of both

serial ports can be found in the Ultra-High-Speed Flash Microcontroller User’s Guide.

Instruction Set

All instructions are 100% binary compatible with the industry-standard 8051, and are only different in the number of

machine cycles used for the instructions. There are some special conditions and features to be considered when

analyzing the DS89C430 instruction set. Full details are available in the Ultra-High-Speed Flash Microcontroller

User’s Guide.

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