4.8 Digital I/o register

There are 16 digital input channels and 16 digital output channels are provided by the ACL-8112. The address Base + 6 and Base + 7 are used for digital input channels, and the address Base + 13 and Base + 14 are used for digital output channels.

Bit	7	6	5	4	3	2	1	0
Base + 6	DI7	DI6	DI5	DI4	DI3	DI2	DI1	DI0
Base + 7	DI15	DI14	DI13	DI12	DI11	DI10	DI9	DI8

Address : BASE + 6 & BASE + 7

Attribute : read only

Data Format:

Bit	7	6	5	4	3	2	1	0
Base+13	DO7	DO6	DO5	DO4	DO3	DO2	DO1	DO0
Base +14	DO15	DO14	DO13	DO12	DO11	DO10	DO9	DO8

Address : BASE + 13 & BASE + 14

Attribute : write only

Data Format:

4.9 D/a Output Register

The D/A converter will convert the D/A output register data to the analog signal. The register data of the address Base + 4 and Base + 5 are used for D/A channel 1, Base +6 and Base +7 are used for D/A channel 2.

Bit	7	6	5	4	3	2	1	0
Base + 4	DA7	DA6	DA5	DA4	DA3	DA2	DA1	DA0
Base + 5	X	X	X	X	DA11	DA10	DA9	DA8

Address : BASE + 4 & BASE + 5

Attribute: write only

Data Format: (for D/A Channel 1)

Bit	7	6	5	4	3	2	1	0
Base + 6	DA7	DA6	DA5	DA4	DA3	DA2	DA1	DA0
Base + 7	X	X	X	X	DA11	DA10	DA9	DA8

Address : BASE + 6 & BASE + 7

Attribute : write only

Data Format: (for D/A Channel 2)

DA0 is the LSB and DA11 is the MSB of the 12 bits data.

X : don't care

Note : The D/A registers are "double buffered" so that the D/A analog output signals will not updated until the second (high) byte is written. This can insure a single step transition when the D/A conversion.

4.10 Internal Timer/Counter Register

Base + 0	Counter 0 Register ( R/W)
Base + 1	Counter 1 Register ( R/W)
Base + 2	Counter 2 Register ( R/W)
Base + 3	8254 CONTROL BYTE

Two counters of 8254 are used for periodically triggering the A/D conversion; the left one is left free for user applications. The 8254 occupies 4 I/O address locations in the DAS BOARD as shown blow. Users can refer to NEC's or Intel's data sheet for a full description of the 8254 features, condensed information is specified in Appendix B.

Address : BASE + 0 ~ BASE + 3

Attribute : read / write

Data Format:

4.11 Low-level Programming

To operate the ACL-8112, users should understand how to write a hardware dependent low-level program. Using either the assembly or the high-level language can perform the low-level programming. In Appendix B, the low-level programming syntax is introduced.