Connect this pin to 3.3V power source. This signal
provides power to the analog section of the chip.
Analog VCC.
Connect this pin to 3.3V power source. This signal
provides power to the analog section of the chip.
Analog Ground.
Connect to ground with as short a path as possible.
Analog Ground.
Connect to ground with as short a path as possible.
USB D鈥?Signal.
Connect to the USB D鈥?signal.
USB D+ Signal.
Connect to the USB D+ signal.
8051 Address Bus.
This bus is driven at all times. When the 8051 is
addressing the internal RAM it reflects the internal address.
N/A
N/A
N/A
N/A
Z
Z
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
Z
Z
Z
Z
Z
Z
Z
Z
H
8051 Data Bus.
This bidirectional bus is high impedance when
inactive, input for bus reads, and output for bus writes. The data bus is
used for external 8051 program and data memory. The data bus is
active only for external bus accesses, and is driven LOW in suspend.
Program Store Enable.
This active LOW signal indicates an 8051
code fetch from external memory. It is active for program memory
fetches from 0x4000鈥?xFFFF when the EA pin is LOW, or from
0x0000鈥?xFFFF when the EA pin is HIGH.
Breakpoint.
This pin goes active (HIGH) when the 8051 address bus
matches the BPADDRH/L registers and breakpoints are enabled in the
BREAKPT register (BPEN = 1). If the BPPULSE bit in the BREAKPT
register is HIGH, this signal pulses HIGH for eight 12-/24-/48 MHz
clocks. If the BPPULSE bit is LOW, the signal remains HIGH until the
8051 clears the BREAK bit (by writing 鈥?鈥?to it) in the BREAKPT register.
34
28
BKPT
Output
L
Note
6. Do not leave unused inputs floating. Tie either HIGH or LOW as appropriate. Pull outputs up or down to ensure signals at power up and in standby. Note that no pins
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