Leap in Performance with 8051 Compatibility

EZ-USB Series 2100

To write data to outside logic, the 8051 loads a data pointer with a USB FIFO register address, and then executes a “movx a,@dptr” instruction to move a byte from the FIFO to the 8051 accumulator. The EZ-USB core simultaneously broadcasts the FIFO data on the external data bus pins and generates the external write signal FWR# (Fast Write). A 24 MHz clock is provided for use as an external FIFO clock, if required. EZ-USB control bits allow the timing and polarity of the FWR# signal to be tailored for different external interface requirements.

To read data from outside logic, the 8051 loads a data pointer with a USB FIFO register address, and then executes a “movx @dptr,a” instruction to move a byte from the accumulator to the FIFO. The EZ-USB core discards the accumulator data and instead writes a byte from the external data bus pins to the FIFO. The EZ-USB core provides the external read signal FRD# (Fast Read) to strobe the data, and a 24 MHz clock. Like the FRW# signal, the FRD# signal may be tailored for different interface requirements.

A Leap in Performance with 8051 Compatibility

The enhanced 8051 processor increases performance by executing most instructions in four clock cycles instead of twelve, as in the standard 8051. The enhanced 8051 core also runs at 24 MHz; that’s twice as fast as the standard part. These factors improve the execution rate for most instructions by a factor of five. The enhanced 8051 core contained in the EZ-USB family is binary-code compatible and performs the same functions as the industry- standard 8051. The effects of

instructions on bits, flags, and		support extra features such as a
other status functions are identi-		second data pointer, a second
cal to the standard 8051. The		UART, cycle-stretched timing, an
enhanced 8051 core also provides		expanded interrupt system, and
special function registers that		enhanced timers.

	Feature	Standard	Anchor
	Clocks per instruction cycle	12	4
	Data pointers	1	2
	Serial ports (UARTs)	1	2
	16-bit timers	1	3
	Interrupt sources (int and ext)	5	13
	Stretch memory cycles	No	Yes
	Nominal operating frequency	12 MHz	24 MHz
	Nominal operating voltage	5 V	3.3 V