Parallel I/O Interface
The Parallel Interface and Timer module (PIT 68230) is used to provide powerful asyn-
chronous parallel I/O on PME 68-1B boards. The PIT provides 24 I/O lines, 4
control lines and a 24-bit timer with a 5-bit prescaler. A Centronics type interface can be
configured. Figure 9 is a hardware connection example.
The PIT is accessed via P2, the 64-pin male VMEbus connector. Access via a synchro-
nous bus structure and the non-multiplexed data/address bus allows the PIT to communi-
cate without any CPU wait-states.
The PIT includes the following features:
·
Mode selection
- Bit I/O
- Unidirectional 8-bit and 16-bit
- Bidirectional 8-bit and 16-bit
·
Selectable handshaking options (This is done via the software and reference
should be made to a PIT data sheet.)
·
24 bit programmable timer with 5-bit prescaler
·
Software programmable timer modes
·
2 selectable interrupt sources
·
Registers are readable and writeable
·
All registers are directly addressable
PIT Addressing
All PIT registers are directly addressable and are readable or read/writeable depending
on the register selected (see Table 5).
Only single byte transfers to or from the PIT on data bits D0 to D7 are allowed (i.e. odd
addresses).
Caution
:
The PIT interrupts the processor on auto-interrupt vector number 5 and
does not supply the processor with a vector number during interrupt
acknowledge cycles. So, programming the Port Interrupt Vector Register
(PIVR) has no effect.
PME68-1B Manual
Page 28 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...
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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...
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