DS89C430 Maxim, DS89C430 Datasheet - Page 43

• Manufacturer Part Number: DS89C430
• Description: The DS89C430 and DS89C450 offer the highest performance available in 8051-compatible microcontrollers
• Manufacturer: Maxim

DS89C430/DS89C450 Ultra-High-Speed Flash Microcontrollers
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 V
should drop below the V
level. If BGS is 0, no
CC
RST
reset is generated if V
drops below V
.
CC
RST
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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