Rabbit 6000 User’s Manual
digi.com
405
36.2 Operation
36.2.1 Unused Pins
Input (or bidirectional) pins that are unused in a design can pick up noise that may cause the tran-
sistors in the input buffer to switch states quickly, causing unnecessary current draw and in the
worst case possibly damaging the processor. To avoid this, all unused pins should be connected to
a weak pullup or pulldown resistor (approximately 100 k
) and left as inputs. This provides pro-
tection from noise when the pin is an input, but also limits the current draw if the pin gets inadver-
tently enabled as an output.
Note that the parallel port pins can all be configured with internal pullup/pulldown resistors. Exter-
nal components are not required if these internal resistors are enabled at startup.
36.2.2 Unused Peripherals
All peripherals in the Rabbit 6000 use gated clocks, which disable the clock input to a peripheral
whenever it is not enabled for use. Disabling any peripherals not being used will help reduce
power. The A/D converter and D/A converter peripherals have sleep modes that can be enabled
when they should remain active but are not being directly used.
The Ethernet and Wi-Fi peripherals in particular can draw a significant amount of current when
powered, as shown in Table 36-1. Exercise care that they are only enabled when being used.
36.2.3 Clock Rates
The processor and peripheral clocks in the Rabbit 6000 can be run in six different modes using the
main oscillator or the main PLL: full speed; divided by 2, 4, 6, or 8; and the processor clock divided
by 8 with the peripheral clock at full speed. If the clock doubler is enabled, the options also
include twice the main oscillator frequency and the main oscillator divided by 3.
In addition, the 32 kHz clock can be used for the processor and peripheral clocks; the 32 kHz clock
can also be divided by 2, 4, 8, or 16, which provides dramatically lower power consumption.
Table 36-1. Current Draw by Selected Rabbit 6000 Peripherals
Peripheral
Typical Additional
Current
Ethernet
13 mA @ 1.2 V
196 mA @ 3.3 V
Wi-Fi
54 mA @ 1.2 V
9 mA @ 3.3 V
Содержание 6000
Страница 1: ...Rabbit 6000 Microprocessor User s Manual 90001108_J...
Страница 11: ...Rabbit 6000 User s Manual digi com 11 1 3 Block Diagram Figure 1 1 Rabbit 6000 Block Diagram...
Страница 43: ...Rabbit 6000 User s Manual digi com 43 4 1 1 Block Diagram...
Страница 57: ...Rabbit 6000 User s Manual digi com 57 5 1 1 Block Diagram...
Страница 88: ...Rabbit 6000 User s Manual digi com 88 7 2 Block Diagram...
Страница 115: ...Rabbit 6000 User s Manual digi com 115 11 1 1 Block Diagram...
Страница 127: ...Rabbit 6000 User s Manual digi com 127 12 1 1 Block Diagram...
Страница 138: ...Rabbit 6000 User s Manual digi com 138 13 1 1 Block Diagram...
Страница 154: ...Rabbit 6000 User s Manual digi com 154 15 1 1 Block Diagram...
Страница 163: ...Rabbit 6000 User s Manual digi com 163 16 1 1 Block Diagram...
Страница 170: ...Rabbit 6000 User s Manual digi com 170 17 1 1 Block Diagram...
Страница 177: ...Rabbit 6000 User s Manual digi com 177 18 1 1 Block Diagram...
Страница 186: ...Rabbit 6000 User s Manual digi com 186 19 1 1 Block Diagram...
Страница 230: ...Rabbit 6000 User s Manual digi com 230 22 2 Block Diagram...
Страница 234: ...Rabbit 6000 User s Manual digi com 234 Figure 22 3 Sample Slow A D Converter Circuit...
Страница 287: ...Rabbit 6000 User s Manual digi com 287 25 1 1 Block Diagram...
Страница 310: ...Rabbit 6000 User s Manual digi com 310 26 1 1 Block Diagram...
Страница 323: ...Rabbit 6000 User s Manual digi com 323 28 1 1 Block Diagram...
Страница 351: ...Rabbit 6000 User s Manual digi com 351 31 1 4 Block Diagram...
Страница 361: ...Rabbit 6000 User s Manual digi com 361 32 1 1 Block Diagram...
Страница 369: ...Rabbit 6000 User s Manual digi com 369 33 2 Block Diagram...
Страница 390: ...Rabbit 6000 User s Manual digi com 390 35 1 1 Block Diagram...
Страница 408: ...Rabbit 6000 User s Manual digi com 408...
Страница 410: ...Rabbit 6000 User s Manual digi com 410...
Страница 411: ...Rabbit 6000 User s Manual digi com 411...
Страница 420: ...Rabbit 6000 User s Manual digi com 420 Figure 37 1 Memory Read and Write Cycles...