The PIT interrupt signal lines (PC3 + PC5) can both be linked to interrupt request
level 5. Auto-interrupt vectoring is used, the fixed interrupt vector number for the PIT
(level 5) is # 29. The PIT interrupt signal line PC3 can also be linked to interrupt at level
6 if the RTC interrupt is disabled.
Address $000074 is the start address of the PIT handling routine (for level 5). Please re-
fer to the PIT 68230 data sheet (available from your supplier) which provides program-
ming information for the PIT.
Centronics Type Interface
The PIT can be used as a Centronics-type parallel interface. This allows connection of a
Centronics compatible printer with the handshake protocol under full software control.
See Chapter 4 for further details.
Figure 9 below shows how the PIT may be user configured as a Centronics type
interface. The diagram shows how a 74LS645 can be employed to give extra buffering on
the data and strobe lines. This allows cable length to be extended to approximately 5m
(16 ft).
Figure 9 Example of a Centronics Type Interface
PIT Summary
Access address:
$0E0001 - $0E0035
Access mode:
Byte Mode (odd only)
Usable data bits:
D0 to D7
Interrupt level:
5 (auto-interrupt vectoring)
Interrupt vector:
Fixed # 29
Address: $000074
31
27
26
25
24
23
22
21
17
14
18
13
+ 5V
1
20
10
11
+ 5V
PA0
PA1
PA2
PA3
PA4
PA5
PA6
H2
GND
H1
PB0
2
3
4
5
6
7
8
1
10
13
12
19
74LS645
D0
D1
D2
D3
D4
D5
D6
DATA STROBE*
ACK*
SELECT
PAPER OUT
GND
PME68-1B Manual
Page 30 Issue 5
Содержание PME 68-1B
Страница 8: ...Figure 1 The PME 68 1B Board Photograph not available in PDF PME 68 1B Manual Page 2 Issue 5...
Страница 12: ...Figure 4 Component Layout Diagram P5 P4 P3 BAT PME 68 1B Manual Page 6 Issue 5...
Страница 56: ...Figure 14 Link Areas BAT PME68 1B Manual Page 50 Issue 5...
Страница 57: ...Blank Page PME68 1B Manual Page 51 Issue 5...
Страница 59: ...Figure 15 Location of System EPROM Area 1 2 3 4 1 2 3 4 WC1 WC2 PME68 1B Manual Page 53 Issue 5...
Страница 80: ...Figure 41 Location of BERR Jumpers 1 2 3 4 WK1 WK2 BR26 2 3 1 BAT PME68 1B Manual Page 74 Issue 5...
Страница 132: ...Blank Page PME68 1B Manual Page 126 Issue 5...