A.6
8051 Core/DS80C320 Differences
The 8051 core is similar to the DS80C320 in terms of hardware features and instruction cycle
timing. However, there are some important differences between the 8051 core and the
DS80C320.
A.6.1 Serial Ports
The 8051 core does not implement serial port framing error detection and does not implement
slave address comparison for multiprocessor communications. Therefore, the 8051 core also
does not implement the following SFRs: SADDR0, SADDR1, SADEN0, and SADEN1.
A.6.2 Timer 2
The 8051 core does not implement Timer 2 downcounting mode or the downcount enable bit
(TMOD2, bit 0). Also, the 8051 core does not implement Timer 2 output enable (T2OE) bit
(TMOD2, bit 1). Therefore, the TMOD2 SFR is also not implemented in the 8051 core.
Also, the 8051 core Timer 2 overflow output is active for one clock cycle. In the DS80C320,
the Timer 2 overflow output is a square wave with a 50% duty cycle.
A.6.3 Timed Access Protection
The 8051 core does not implement timed access protection and therefore, does not implement
the TA SFR.
A.6.4 Watchdog Timer
The EZ-USB/8051 does not implement a watchdog timer.
EZ-USB TRM v1.9
Appendix A: 8051 Introduction
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