
EZ-USB FX2 Technical Reference Manual
Page 11-2 EZ-USB FX2 Technical Reference Manual v2.1
11.2 8051 Enhancements
The FX2 uses the standard 8051 instruction set, so it’s supported by industry-standard 8051 com-
pilers and assemblers. Instructions execute faster on the FX2 than on the standard 8051:
• Wasted bus cycles are eliminated; an instruction cycle uses only four clocks, rather than
the standard 8051’s 12 clocks.
• The FX2’s CPU clock runs at 12MHz, 24MHz, or 48MHz —up to four times the clock
speed of the standard 8051.
In addition to speed improvements, the FX2 includes the following architectural enhancements to
the CPU:
• A second data pointer
• A second USART
• A third, 16-bit timer (TIMER2)
• A high-speed external memory interface with a non-multiplexed 16-bit address bus
• Eight additional interrupts (INT2-INT6, WAKEUP, T2, and USART1)
• Variable MOVX timing to accommodate fast and slow RAM peripherals
• Two Autopointers (auto-incrementing data pointers)
• Vectored USB and FIFO/GPIF interrupts
• Baud rate timer for 115K/230K baud USART operation
• Sleep mode with three wakeup sources
• An I²C-compatible bus controller that runs at 100 or 400 KHz
•FX2-specific SFRs
• Separate buffers for the SETUP and DATA portions of a USB CONTROL transfer
• A hardware pointer for SETUP data, plus logic to process entire CONTROL transfers
automatically
• CPU clock-rate selection of 12, 24 or 48MHz
• Breakpoint facility
• I/O Port C read and write strobes
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