Xycom XVME 200, Руководство пользователя

Страница: 38 / 57

XVME-200/290 Manual
December, 1987
E x a m p l e #l
Basic Set Up:
.
PI/T #l
Mode 0 = Unidirectional 8-bit Mode
Submode 1X = Bit I/O (Pin-Definable Single-Buffered Output or Non-Latched
Input)
Goals:
1)
Port A, all bits = non-latched inputs.
2)
Port B, all bits = single buffered outputs.
3)
Port C, bit 0 = single buffered output (controls the direction of the
transceiver connected to Port A).
4)
Port C,
l
bit 1 = single buffered output (controls the direction of the
transceiver connected to Port B).
5)
Port C, bit 2 = non-latched input.
6)
Port C, bit 3 = single-buffered output (high).
7)
Port C, bit 4 = single-buffered output (programmed high to disable timer
interrupts).
8)
Port C, bit 5 = PIRQ* function.
9)
Port C, bit 6 = PIACK* function.
10) Port C, bit 7 = non-latched input (will always read as one).
11) The handshake pins (Hl,H2,H3,H4) are at a low voltage level when negated,
and at a high voltage level when asserted.
12) Hl is an edge-sensitive status input, HlS is set by an asserted edge of Hl.
13) H2 is a negated output pin and H2S is always cleared.
14) H3 is an edge-sensitive status input, H3S is set by an asserted edge of H3.
15) H4 is an asserted output pin and H4S is always cleared.
16) All interrupts are disabled.
17) The timer is disabled.
CODE:
M0VEA.L # PI/TlBASE,AO
M0VE.B #$FF,PCDR(AO)
M0VE.B #$l B,PCDDR(AO)
M0VE.B #$OF,PGCR(AO)
MOVE.B #$AO,PACR(AO)
; A0 = base address of PI/T #l
; Initialize Port C control
; functions
; Port A ‘ & B transceivers = output
; PC3/TOUT = high
; PC4 = high (timer interrupts disabled)
; PC7,6,5,2 = inputs
; Port mode = 0
; H34,H12 interrupts disabled
; Handshake pins = active high
; Initialize Port A
; Submode 1X
; H2 = negated output
; HI & H2 interrupts disabled
3-11