Autoloading - Canon EOS 55 Service Manual

Part 2: Technical Information
2.6 Autoloading
1.
When film is installed and the back cover closed, the LCD-DR feels the change in
the BPSW (back cover switch) and fires up the DC/DC convector.
2. The MPU communicates with the LCD-Dr and reads the switch inputs to determine
which switch changed states.
3. When
it
finds that BPSW has changed and is now closed,
it
checks the state of the
cartridge switch PTIN-SW, and if a cartridge is installed, the autoloading sequence is
initiated.
4. The battery is checked.
5. A pause of lOOms allows the cartridge to stabilize.
6. The DX code is read.
7. The MPU controls the motor drivers MDI and MD2 through the MlF and MIR lines
to drive the motor in the normal direction. This switches the motor to the film wind-
ing phase.
8. The motor is then reversed to start the actual film winding.
9. The film sensor's photoreflector (PR-FILM) data PRAD is A/D converted (edge read-
ing) to count the perforations transported, and determine the comparator level for
use during winding.
IO.After approximately 3.5 frames are wound, the motor is stopped and a "l" is dis-
played on the LCD.
11. The motor turns forward to return to the flash ready position. (This is the initial, or
home, position for all operations.
0
DX5
77
0
DX4
76
0
DX3
80
DX2 7
LCD Dr
78
<D
;:::
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"'
...
re
BP
,._ ,._ ,._
cii 0
0
Cl)
::. ~
P.GND
...
;:::
.,,
CX)
,._
Rsw:
'
a,
<D <D <D
'
47K : '
-
-
'
MD2
RSFD'"" 1 ~ - - ~
re
CMSP1 58 45 PRON
MPU
44 PRAD
~----.FWD
PGND>-" 12
~ - - - - + - .
~--'-IREV FSRDP--'---~
~
CMSP2
94
CMSP3 95
u.
a:
i i
CM 0.1
MD1
~ ~ RSFD>-'-' 13
~----<----<>---'
' - - ! - - - - - - - - - - - - < . + - - - o - - - - - " - 1
6 FWD PGND>-" 12 ~ - - + - - + - ~
' - - - - - - - - - - - - + - + . . - - - - - ' - 1
7 REV
FSRDl-'-ll.,_____,
Fig. 2-27 Film Transport
2-35