ATTENUATOR Controller

Control unit - hardware description

Control unit is a simple microprocessor system based on ATMEL 89C51 chip (Intel 8051 family). There is small LCD display (4 lines) and keyboard (12 keys). Two 9-pin connectors link the device to:  
Schematic diagram of power supply [gif, 300dpi, 10kB]  Power supply provides 9VDC (device accepts 7-12V AC or DC, of any polarity - see diagram) 
Beautiful box is prepared by Michael Knapp from Hasylab:
View of Attenuator Controller [jpg, 300dpi, 47kB]

Steering two motors is done by 8 electro-mechanical switches (see blue chips on the picture below).

View of Attenuator Controller inside (electronic board) [jpg, 300dpi, 72kB]
 
 
 
Schematic diagram of switches section [gif, 300dpi, 65kB] Each pair of the switches generates 0V/5V power signal for one wire; two such a signals (two pairs of switches, two wires) power one motor in both directions. Obviously, applying wrong signal to switches can cause their damage (you can't try to apply 0V and 5V to the same wire). 
GAL16V8 logic array provide correct signal for switches. Due to high output current (up to 20mA) it can drive the switches directly. 
 
 
ATMEL 89C51 is CPU of the board. It reads 5 lines from keyboard (keys: '4', '6', '7', '9' and '5' & '8') and 4 lines from attenuation wheels (2 limit switches, 2 reset switches). It drives 6 lines of motors (M0_LEFT, M0_RIGHT, M0_ON, M1_LEFT, M1_RIGHT, M1_ON) and keeps communication to LCD display (8 data lines + 3 controls/handshakes).
 
 Schematic diagram of CPU section [gif, 300dpi, 57kB]

 For details refer to ATMEL (89C51), Lattice (GAL16V8) or mail me.

Connection table: 

;///////////////////////////////////////////////////////////
;       att_brd.h       -       attenuator board layout
;       ---------               -----------------------
;
;       This file defines labels corresponding to physical
;       circuit wirings.
;       
;       15:18 20.11.1999 Hamburg, roman pielaszek
;
;
;LCD conn.
;-----------
;pin#   name
;1      +5V
;2      contrast
;3      E                               5       P1.4
;4      nc
;5      RS                              7       P1.6
;6      GND
;7      D7                              32      P0.7
;8      D6                              33      P0.6
;9      D5                              34      P0.5
;10     D4                              35      P0.4
;11     D3                              36      P0.3
;12     D2                              37      P0.2
;13     D1                              38      P0.1
;14     D0                              39      P0.0
;15     nc
;16     R/W                             6       P1.5
;               
;///////////////////////////////////////////////////////////
;       LCD labels      should be already defined in hardware board section (e.g. att_brd.h or 80c535.h) !
;       ----------
;
LCD_E           EQU     P1.4
LCD_RW          EQU     P1.5
LCD_RS          EQU     P1.6
LCD_DATA        EQU     P0  
; 
; 
;
;
; 
;KBD conn.      GAL16V8                 8951            meaning (active: 0VDC)
;-----------    ------------            ------------    ---------------
;pin#   name    pin#    name            pin#    name
;               1       I0              8       P1.7    M1: reset switch signal (???)
;11             2       I1              25      P2.4    M1: direction: left
;2              3       I2              26      P2.5    M1: direction: right
;6              4       I3              27      P2.6    M1: motor on/off
;               5       I4              28      P2.7    M1: limit switch signal
;13             6       I5              21      P2.0    M0: direction: left
;5              7       I6              22      P2.1    M0: direction: right
;9              8       I7              23      P2.2    M0: motor on/off
;               9       I8              24      P2.3    M0: limit switch signal
;               
;               11      I9              4       P1.3    M0: reset switch signal (???)
;       
;KBD connector          GAL16V8
;-------------          ------------
;pin#   name            pin#    name
;1      GND
;2                      3   
;3
;4
;5                      7
;6                      4
;7
;8      GND
;9                      8
;10
;11                     2
;12     GND
;13                     6
;
;