rtd DM6210, Руководство пользователя

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1-4
Fig. 1-2 — 8254 Timer/Counter Clock Source Jumpers, JP1
Fig. 1-3 — 8254 Timer/Counter Circuit Block Diagram
JP1 — 8254 Timer/Counter Clock Sources (Factory Settings: CLK0-OSC, CLK1-OT0, CLK2-OT1)
This header connector, shown in Figure 1-2, lets you select the clock sources for the 8254 timer/counters,
TC0, TC1, and TC2. The factory setting cascades all three timer/counters, with the clock source for TC0 being the
on-board 8 MHz oscillator, the output of TC0 providing the clock for TC1, and the output of TC1 providing the
clock for TC2. You can connect any or all of the sources to an external clock input through the CN3 I/O
connector, or you can set TC1 and TC2 to be clocked by the 8 MHz oscillator. Figure 1-3 shows a block
diagram of the timer/counter circuitry to help you with these connections.
NOTE: When installing jumpers on this header, make sure that only one jumper is installed in each group
of two or three CLK pins.
JP1
OSC
EC0
OT0
OSC
EC1
OT1
OSC
EC2
CLK0
CLK1
CLK2
CLK0
6210
I/O CONNECTOR
CN3
PIN 46
PIN 43
PIN 42
8254
TIMER/
COUNTER
0
CLK
GATE
OUT
TIMER/
COUNTER
1
CLK
GATE
OUT
TIMER/
COUNTER
2
CLK
GATE
OUT
PIN 39
PIN 44
XTAL (8 MHz)
JP1
+5 V
+5 V
+5 V
PIN 19
PIN 40
PIN 41
PIN 45
T/C OUT 0
OUT0
OUT1
EXT CLK 0
T/C OUT 1
EXT CLK 1
EXT GATE 2
T/C OUT 2
EXT CLK 2
EXT GATE 0
EXT GATE 1
EC0
OSC
EC1
OSC
EC2