Omega Engineering IOP-241 - Manual (Page 31)

5.10 Programming Example
The following C program segment demonstrates how to program an IOP-241 located at I/O
base address 300h. Port A will be programmed as output, and 55h will be latched at Port A.
Port B will be configured with it's upper 3 bits as output and it's lower five bits as input. The
upper three bits will be latched with 010b. Port C will be configured as input. Interrupts will
be enabled as explained in the program comments.
outp(0x300,0x55); /* writes 55h to Port A */
outp(0x301,0x5F); /* writes 010b to Port B upper 3 bits*/
/* sets Port B lower 5 bits for input */
outp(0x302,0xFF); /* initializes Port C for input */
Port_B = inp(0x301); /* reads data from Port B */
/* Port_B(bit7) = '0' and Port_B(bit5) = '0' due to 'masking' */
Port_C = inp(0x302); /* reads data from Port C */
outp(0x306,0x76);
/* INT7 - INT4 set for Level Sensitive Active High Interrupt Mode */
/* INT3 - INT0 set for Edge Sensitive High-to-low Transition Interrupt Source */
/* External Interrupt Source Enabled */
/* External Interrupt Source set for Low-to-high Edge Sensitive Interrupt Source*/
outp(0x305,0x77);
/* Enables six Port C interrupt sources */
/* Enables INT6,INT5,INT4,INT2,INT1,INT0 */
IOP-241 Users Manual 31