Measurement Computing CIO-DAS08-PGH - Manual (Page 17)

4: REGISTER ARCHITECTURE
4.1 CONTROL & DATA REGISTERS
The CIO-DAS08-PGx is controlled and monitored by writing to and reading from eight consecutive 8-bit I/O addresses. The first
address, or BASE ADDRESS, is determined by setting a bank of switches on the board.
Register manipulation is best left to experienced programmerss as most of the possible functions are implemented in easy to use
Universal Library™.
The register descriptions follow the format:
A/D8 A/D7 A/D6 A/D5 A/D4 A/D3 A/D2 A/D1
0 1 2 3 4 5 6 7
Where the numbers along the top row are the bit positions within the 8-bit byte and the numbers and symbols in the bottom row is
the function associated with each bit.
To write to or read from a register in decimal or HEX, the bit weights listed in table 4-1 apply.
Table 4-1. Register Bit Weights
80 128 7
40 64 6
20 32 5
10 16 4
8 8 3
4 4 2
2 2 1
1 1 0
HEX VALUE DECIMAL VALUE BIT POSITION
To write control words or data to a register, the individual bits must be set to 0 or 1 then combined to form a byte.
The method of programming required to read/write bits from bytes is beyond the scope of this manual.
In summary form, the registers and their function are listed in Table 4-2. Each register has eight bits which may constitute a byte
of data or eight individual bit read/write functions.
Table 4-2. Board Register Functions
Counter Control Not Used BASE +7
Load Counter 2 Read Counter 2 BASE +6
Load Counter 1 Read Counter 1 BASE +5
Load Counter 0 Read Counter 0 BASE +4
Programmable Gain Control Channel MUX and Gain Status BASE +3
OP1-OP4, INTE & MUX
Address EOC, IP1-IP3, IRQ, MUX
Address BASE +2
Start 12 Bit A/D Conversion A/D Bits 1(MSB)-8 BASE +1
Start 8 Bit A/D Conversion A/D Bits 9-12 (LSB) BASE
WRITE FUNCTION READ FUNCTION ADDRESS
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