Appendix B: Digital I/O
One characteristic of digital circuit is its fast response to high or low signal. This kind of response is highly needed for harsh and critical industrial operating environment. Digital Input and Output, generally, are control signals. You can use these signals to control external devices that needs On/Off circuit or TTL devices. You can read or write data to the selected address to enable the function of digital IO.
Users could test GPIO function under ‘Debug.exe’ program as follow:
GPO Example | Description |
O 2E 87 | ;Eetended Functions Enable Register |
O 2E 87 | ;Eetended Functions Enable Register |
O 2E 2A | ;Select CR2A |
O 2F FC | ;(Define the PINs as GPIO or Game Port 1) |
| “FC” Pin 121~128 set as GPIO |
O 2E 07 | ;EFIR=EFER(Extended Functions Index |
| Register)point to Logical Device Number Reg. |
O 2F 07 | ;EFDR=EFIR+1(select logical device 7,GPIO in |
| logical device 7) |
O 2E 30 | ;select CR30(Active or inactive) |
O 2F 01 | ;set 01(Active), 00(inactive) |
O 2E F0 | ;select CRF0(Set the PINs be GPO or GPI |
| Function) |
O 2F 00 | ;set the PINs be GPO |
O 2E F2 | ;select CRF2(Output High/Low) |
O 2F 00 | ;set the PINs be all Low Level(FF=all High |
| Level) |
O 2E F1 | ;select CRF1 |
O 2F FF | ;set the Output to be FF(all High) |
O 2E AA | ;exit EFER |
Q | ;quit debug |
