Measurement Computing PC104-CTR10HD - Manual (Page 10)

3.0 CONTROL & DATA REGISTERS
The PC104-CTR10HD has two AM9513 counter/timer chips, “#1” and “#2” (refer
back to Figure 2-3). Each AM9513 contains five counters of 16 bits each. Associated
with each counter are:
1. an input source,
2. a count register,
3. a load register,
4. a hold register,
5. an output
6. a gate.
Unlike an Intel 8254 which has a single source, single gate and unique I/O address for
each counter, the AM9513 is fully programmable and any counter may be internally
connected to any gate and receive it's counts from a number of sources. In addition,
each counter does not have a unique I/O address. The AM9513 takes only two
addresses per chip, one of which is a data path to the counter's load and hold registers.
There is no AM9513 register information in this manual. If you wish to know more
about programming the AM9513, please call Technical Support.
We suggest that you use the Universal Library, rather than resort to programming the
AM9513 directly. Since programming support is available through the Universal
Library, we do not supply help with other AM9513 programming.
The PC104-CTR10HD is an I/O-mapped expansion board which occupies four
addresses plus a control address.
The first address, or BASE ADDRESS, is determined by setting a bank of switches on
the board.
A register is easy to read and write to. Most often, register manipulation is best left to
experienced programmers as most of the PC104-CTR10HD possible functions are
implemented in the easy to use Universal Library routines.
The register descriptions follow the format:
A0 A1 A2 A3 A4 A5 A6 A7
0 1 2 3 4 5 6 7
Numbers along the top row are the bit positions within the 8-bit byte and the numbers
and symbols in the bottom row are the functions associated with that bit.
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