Publicidad
V4059
Note: Thumbwheel switches, Reset, Load Counter, Load
Register, Up/Down, and Store switches are external to the
board.
Gold contact switches are recommended.
Table 1 - 7217 Multiplex Rate Control
Scan
Nominal
Capacitor
Oscillator
C Scan
Frequency
None
2.5 kHz
20 pF
1.25 kHz
90 pF
600Hz
Two printed circuit boards supplied as a pair, the master board
accepting a 7217, 4 decade counter drive IC, and all associated
components required to drive four 7 segment LED displays. The display
board accepts four 0.3 in or 0.43 in 7 segment common anode LH
decimal point LED displays and can accommodate, if desired, display
bezel RS stock no. 587-204.
Assembly
All relevant components and connections are marked on both boards.
Shorting links are indicated by dotted lines on the master board and
solid lines on the display board. Connections may be made using RS
inter PCB connectors or via the solder pads provided. In addition all
facilities of the 7217 are brought out into a 16-way gold plated edge
plug.
The connections for the display board are made at the edge from the
contact pads 1 to 20. Pads 1,2,218,19 and 20 are not used. Table 1
gives the 'pad out' configuration.
Table 2 'pad-out' configuration
Pad
Function
3
DP Digit 1
4
DP Digit 0
5
Digit 1 Common
6
Digit 0 Common
7
a
8
b
9
c
10
d
11
e
12
g
13
f
14
Digit 3 Common
15
Digit 2 Common
16
DP Digit 3
17
DP Digit 2
When thumbwheel switches are being used to programme the 7217 all
of the diodes (IN4148 or OA47 for improved noise margin) must be
mounted on the master board. Row 'E' will be the common of each
switch and row 'C' the BCD output of the corresponding digit. If the
switches are not required ie when a number is to be constantly set, only
the appropriate diodes need to be mounted between rows 'A' and 'D'.
2
RS Stock No.
434-403
DigitScan
Cycle
Repetition
Time
Rate
(4 digits)
625 Hz
1.6 ms
300 Hz
3.2 ms
150Hz
8 ms
The two-pole four-way DIL switch controls both the position of the
decimal point and the number of zeros, thus the display will show '.0',
'.00', '.000', and '0000' when the switch is changed. If the switch is not
required it can be replaced by two shorting links. For example, if all the
zeros are required with the decimal point in the middle,one link should
be placed across the switch area from the '0000' position to the other
side, and the other link placed from the '00.00' position across the
switch area to the other side.
The miniature pcb slide switch controls the display control pin. In the
'OFF' position, there will be no leading zeros displayed whatever the
position of the two-pole four-way switch, which would then only control
the position of the decimal point. In the 'ON' position, control of the
zeros is made available on the two-pole four-way switch as described
previously. If the slide switch is not required no links are necessary
unless zero control is to be employed when a link should be placed
between centre and top (ON) holes in the switch area.
Both of these switches are disabled (except decimal point control)
when the display control pin on the edge plug is taken low.
RS Components shall not be liable for any liability or loss of any nature (howsoever
caused and whether or not due to RS Components' negligence) which may result
from the use of any information provided in RS technical literature.
NOTA: Los conmutadores rotativos, el reset, el contador de
carga, el registro de carga y los conmutadores
arriba/abajo y memorizar están situados en el exterior de
la tarjeta. Se recomienda utilizar conmutadores con
contactos dorados.
Tabla 1. Control de la velocidad de multiplexado
del 7217
Conden-
Frecuencia
sador de
nominal del
exploración
oscilador
C Scan
ninguno
2,5kHz
20pF
1,25kHz
90pF
600Hz
Dos placas de circuito impreso suministradas como pareja, de las que
la placa maestra acepta un circuito integrado de control de contador
7217 de cuatro décadas y todos los componentes asociados
necesarios para controlar pantallas LED de siete segmentos. La placa
de visualización acepta cuatro visores LED de punto decimal izquierdo
de ánodo común de siete segmentos de 0,3 o 0,43 pulgadas y puede
alojar, si se desea, los engastes para visores de código RS 587-204.
Para más información sobre el 7217, remítase a la hoja técnica 3245.
Montaje
En ambas tarjetas van marcados todos los componentes y conexiones
correspondientes. Las conexiones de puente van indicadas mediante
líneas punteadas en la tarjeta maestra y mediante líneas continuas en
la tarjeta del display. Las conexiones pueden hacerse utilizando
conectores RS inter-PCB o por medio de las placas de soldadura
proporcionadas. Además, todas las posibilidades del 7217 se llevan a
un conector de borde de 16 vías chapado en oro.
Las conexiones para la tarjeta del display se hacen en el borde desde
los terminales de contacto 1-20. Los contactos 1, 2, 18, 19 y 20 no se
utilizan. En la tabla 1 puede verse la configuración de los "contactos de
salida".
Código RS.
434-403
Velocidad de
Tiempo del
repetición de
ciclo de
los dígitos
exploración
(4 dígitos)
625Hz
1,6ms
300Hz
3,2ms
150Hz
8ms
Publicidad
