Canon EOS 7 - ELECTRONIC CIRCUITRY AND POWER SOURCE

1.8 E
LECTRONIC CIRCUITRY
AND POWER SOURCE
(1) Overview
Centering on two CPUs, the electronic circuitry consists
of twenty-four LSIs and ICs, a quartz oscillator, display
elements, and other components. Calculations and the
camera sequence control are executed with 33.554 MHz
clock pulses. The displays and switch-entry detection are
executed with 4.19 MHz clock pulses. Figure 2-21 shows
a block diagram of the circuitry.
(2) CPU Configuration
There are two CPUs. The 32-bit RISC microcomputer mainly detects Eye Control
movements, calculates AF and AE operations, and controls operation sequences. And
the 16-bit microcomputer mainly controls the display system and switches. These
two CPUs operate in parallel and independently from each other. Table 2-9 shows
the main specifications of the two CPUs.
(3) Power source
Two CR123A batteries serve as the power source. The battery check is automatic and
displayed at all times on the LCD panel when the Command Dial is not at the Lock
position.
During bulb exposures, a current of 150 mA flows constantly to the electronic circuit
which includes the electromagnet controlling the 2nd shutter curtain. Maximum
battery life is about 8 hours during a bulb exposure.
Part 2: Technical Information
2-18
Table 2-9 CPU Specifications
Item
1. Main clock
2.
Max. processing speed
3. Commands
4. Performance
5. Internal resistors
6. ROM
7. RAM
8. EEPROM
9. Timer
MAIN CPU
MB91133
33.554MHz
0.03 u
165
Addition & subtraction: 32-bit
Multiplication & division: 32 × 32 → 64-bit
32bit × 16
254KB
8KB
(External: 8 KB)
16bit
× 25
SUB CPU
M30221M3
4.19MHz
0.24 u
91
Addition, subtraction, & division: 16-bit
Multiplication: 16
× 16 → 32-bit
16bit × 20
24KB
1.5KB
—
16bit
× 14
EOS ELAN 7 E / EOS 30
EOS ELAN II / ELAN II E / 50 / 50 E
MB90233
16MHz
0.0625 u
412
Addition, subtraction, multiplication,
& division: 32-bit
16bit × 8
48KB
2KB
(External: 2 KB)
16bit
× 10 8bit × 1
Table 2-8 Electronic Circuit
Components
LSI, IC
Motors
Magnets
Display Elements
Light-emitting Elements
Light-sensing Elements
24
2
0
2
9
4