|
The
68681 Board |
| Testing the
boards output port |
| |
| Assuming the base
address of the board is ADxxxx |
| |
| To turn all
the LED's ON using TUTOR type: |
| MM AD001C |
| FF |
| |
| To turn all
the LED's OFF using TUTOR type: |
| MM AD001E |
| FF |
| |
| Testing the
boards input port |
| |
| Assuming the base
address of the board is ADxxxx |
| |
| To read the
input port using TUTOR type: |
| MD AD001A |
| |
| When the
command above is executed it will return 16 bytes of
data. |
| Only the 2nd
byte displayed is of interest as this is the value of
the input port. |
| |
| Bit 7 is
always 1 |
| Bit 6 will be
1 unless the 68681 IACK pin is low |
| Bit 5 is 1 if
IP5 is high |
| Bit 4 is 1 if
IP4 is high |
| Bit 3 is 1 if
IP3 is high |
| Bit 2 is 1 if
IP2 is high |
| Bit 1 is 1 if
IP1 is high |
| Bit 0 is 1 if
IP0 is high |
| |
| When all the
68681 input port pins (IP0-IP5) are high, the byte value
returned will be FF. |
| |
| To test
individual inputs pull each pin low in turn and check
the byte value returned against the table below: |
| |
| IP5 low - byte
= DF |
| IP4 low - byte
= EF |
| IP3 low - byte
= F7 |
| IP2 low - byte
= FB |
| IP1 low - byte
= FD |
| IP0 low - byte
= FE |
| |
| C0 indicates
ALL the input port pins are low. |
| |