Remote-processing RPC-330 Manuel d'utilisateur télécharger pdf (Page 43)

MULTI-MODE COUNTER SECTION 13

Page 13-1 RPC-330

DESCRIPTION

Both 24 bit multimode counters are capable of up/down,

binary, divide-by-n, and quadrature inputs. Count

frequency is DC to 20 Mhz. The R PC-330 uses an LSI

Computer Systems LS7166. Its data sheet is found in

Appendix C.

The COUNT function and statements are used to read

from and write to the counters. COU NT(0) and

COUNT 0 are used to read and write from P2.

COU NT(1) and COUN T 1 ar e used to re ad and wr ite

from P3. LINEB is used to program the chips for

various operating modes.

Interrupts, using ON ITR, may be detected on a carry,

borrow, or either event. The event is jumper selectable

through H2 or H3. When the counter is used, external

interrupts (see SECTION 12 ) may not be used.

H2 and H3 Description

Pins

1-2 Carry pulse from counter

3-4 Borrow pulse from counter

5-6 Exter nal interr upt

7-8 Carry or borr ow pulse from counter

9-10 Pulse latch using quadrature input

Jumper header H 2 is used for counter 0 and INT 0.

Header H3 is used for counter 1 and INT 1. The LINE

function may be used to read the status of a jumper on

H2 or H3. LIN E(8) reads INT 0 and LINE(9) r eads

INT 1.

The pulse latch (pins [9-10]) must be cleared before

another interrupt is generated and should be cleared

before the first interrupt is generated. See

PROGRAMMING below for further information.

Signals connect to the counter via P2 or P3. The

following table defines signal inputs to the LS7166.

Name Function

An IN Counter input A

Bn IN Counter input B

GND Ground

LD n Load counter/latch (LCTR/LLTC)

GT n Gate/reset counter (ABGT/RCTR)

INT n External TTL interrupt input

Input lines (An IN), (Bn IN), LOAD n, and GATE n are

pulled to + 5V through a 10K resistor.

PROGRAMMING

The LS7166 is capable of several operating modes, all of

which are not discussed here. See Appendix C for this

chips operating modes. What are shown are examples of

how to program this chip.

NOTE: Be sure to initialize the counter chip before

using COU NT com mands. Failure to do so

returns meaningless results.

The COUNT function returns the current counter value.

Specifically, RPBASIC writes a 2 to the MCR (M aster

Control Register), reads the 3 counter bytes from the OL

(Output latch), and converts it to the proper internal

BASIC format.

100 A = COUNT(0)

COUNT statement writes a 24 bit number to the PR

(Preset register) only. Its syntax is:

150 D = 95000

200 COUNT 0,D

A number could be used in place of variable 'D' .

LINEB is used to program and access specific registers

in the LSI7166 chip. In all cases, the bank number is 6.

The address depends upon the specific chip. Use an

address of 1 for counter 0 and 3 for counter 1.

To transfer this number to the counter, execute the

following in the program:

LINEB 6,1,8

Line 100 reads the output status register.

100 A = LINEB(6,1)

200 LINEB6,1,X

Line 200 writes to OCCR, ICR, QR, MCR, and ICR

registers in counter 0. The value ' X' selects a register

determined by bits 6 and 7 in the byte written to the

chip.

When H2[9-10] or H 3[9-10] is jumpered, the output

from a latch is connected to the interrupt line. When the

7166 chip is configured for quadrature encoder and

interrupt when the count reaches a preset number, a very

1 2 ... 38 39 40 41 42 43 44 45 46 47 48

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Remote-processing RPC-330 Manuel d'utilisateur Page 43

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