101-1006 Rabbit Semiconductor, 101-1006 Datasheet - Page 141

• Manufacturer Part Number: 101-1006
• Description: MODULE POWERCORE FLEX 3800
• Manufacturer: Rabbit Semiconductor

Specifications of 101-1006

• Module/board Type: MPU Core Module
• For Use With/related Products: RCM3800
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

B.4.5 Analog I/O
B.4.5.1 A/D Converter Input
The Prototyping Board has one A/D converter circuit, shown below in Figure B-8.
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Figure B-8. PowerCore Prototyping Board A/D Converter Circuit
The ramp generator makes it possible to measure analog voltages using LM339 compara-
tors and the pulse capture capabilities of the Rabbit 3000 microprocessor to convert time
into voltage. One example of this analog measurement capability is the A/D measurement
circuit on the PowerCore Prototyping Board.
The circuit is designed to accept input voltages of 0–10 V. An A/D converter measurement
is implemented when a pulse from the comparator is routed to an input capture, PG5, on
the Rabbit 3000. The counter in the Rabbit 3000 starts at the beginning of the ramp, and
stops when the ramp crosses the input signal. The full scale is approximately 5000 counts,
which yields a measurement resolution of at least 12 bits. The end of the ramp drives an
interrupt in the Rabbit 3000, which then retrieves the count and stores it so that it can be
accessed by a software function call. The interrupt routine can be set up to average inputs
and to detect out-of-range signals.
The absolute accuracy of the voltage measurements is typically better than ± 5 mV.
User’s Manual
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