User`s guide

Operation Theorem
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27
Pacer rate = 2 MHz / (C1 * C2)
Counter 0
Counter 1
Counter 2
CLK0
GATE0
OUT0
CLK1
GATE1
CLK2
GATE2
OUT1
OUT2
2MHz
Oscillator
Vcc
Timer Pacer
8253 Timer/Counter
Not Used
The maximum pacer signal rate is 2MHz/4=500K, which excess the
maximum A/D conversion rate of the ACL-8111. The minimum signal
rate is 2MHz/65535/65535, which is a very slow frequency that user
may never use it.
For example, if you wish to get a pacer rate 2.5 kHz, you can set C1 =
40 and C2 = 10. That is
2.5KHz = 2Mhz / (40 x 20)
External Trigger
Through the pin-1 of CN2 (DI0), the A/D conversion also can be
performed when a rising edge of external signal is occurred. The
conversion rate of this mode is more flexible than the previous two
modes, because the users can handle the external signal by outside
device. The external trigger can combine with the interrupt data transfer,
or even program polling data transfer. Generally, the interrupt data
transfer is often used when external trigger mode is used.
4.1.3 A/D Data Transfer Modes
On the ACL-8111, three A/D data transfer modes can be used when
the conversion is completed. The data transfer mode is controlled by
the mode control register (BASE+11). The different transfer modes are
specified as follows: