Electronic Circuits and Power Sources
(1) Overview
The electronic circuitry in the EOS-1N comprises a total of 9 LSI and IC groups along
with a quartz oscillator, display elements and other circuit components controlled
by two CPUs. Input operations, calculations and sequence control processing are carried
out using digital signals with the exception of the metering IC and some 1/0 functions.
The overall scale of the circuit comprising the camera body, lens and-Power Drive
Booster E1 is equivalent to the EOS-1.
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Breakdown of Principle Circuit Components:- Autofocusing computations are carried out based on a high-speed 12MHz (12 million cycles/see) reference clock pulse, and overall camera sequence control is carried out based on an 8.38MHz clock pulse. |
(2) Twin CPU Configuration The EOS-1N employs a high-speed super microcomputer dedicated to performing AF calculations, and a separate 8-bit CPU for carrying out AE calculations and sequence control, combined in a parallel simultaneous processing twin CPU configuration. This design achieves both faster AF processing speed and improved control precision. The main specifications for the twin CPUs are shown in Table below.
Twin CPUs Specification & Comparison between Canon EOS-1N & EOS-1:-
|
Item |
Canon EOS-1N (16 bits x 5) |
Older Canon EOS-1 model |
||
|
AF CPU |
- |
MAIN CPU |
AF CPU |
|
| Main clock |
TF |
- |
8.38 MHz |
12.0 MHz |
| Minimum calculation time |
12.0 MHz @ 0.166 ps |
- |
0.48 ps |
0.33 |
| Number of instructions |
62 |
- |
146 |
146 |
| Processing capability |
Addition / subtraction / division: @ 32 bit |
- |
Addition / subtraction / division: @ 16 bits; Multiplication: 8 bit |
Addition / subtraction / division: @ 16 bits; Multiplication: 8 bit |
| internal registers |
Multiplication: 16 bit |
- |
8 bits x 2;16 bits x 2 |
16 bits x 5 |
| ROM capacity |
16 bit x 16 |
- |
16K byte |
12288 byte |
| RAM capacity |
48K byte |
- |
512 byte |
512 byte |
| EEPROM capacity |
2K byte |
- |
640 byte |
512 byte |
| Timer |
- |
- |
16 bit x 4; 8 bits x 4 |
16 bits x 5 |
 |
(3) Three (3)
Main LSI and IC Functions The devices below outlined various functions and
purpose in the camera.
M-CPU |
Main Central Processing Unit: Receives input data from various input sources such as the electronic input dials and carries out overall camera sequence control including AE-related processing/control and motor control. Also carries out display control via the LCD driver. | |
AF-CPU |
Auto Focus CPU: An advanced high-speed super-microcomputer dedicated to AF-related processing. Performs data transmission between beeper and EL illumination components. | |
I/O |
Input/Output Interface: Primarily controlled by the AF-CPU, this 1/0 unit functions as an analog interface to the TTL flash metering sensor, as a digital interface to the flash unit, and as an interface to the lens, camera back and BASIS IC. | |
LCD Driver |
This LSI always operates and functions as a driver for the external LCD panel and the viewfinder LCD, Also carries out control of the electronic beeper and EL illumination components. | |
Metering sensor |
This is an LSI made by Canon for carrying out evaluative metering, partial metering and spot metering (via custom function control). It integrates a high-sensitivity sixteen-zone SPC sensor on the same chip with amplifiers for use by the sensor, and is packaged in a clear mold package. This is virtually the same LSI as is used in the EOS 5. | |
Focusing sensor |
This an LS1 made by Canon which integrates the high-precision multi-BASIS AF focusing sensor (including a central cross-type rangefinding sensor and five focusing points), a fine spot metering sensor and amplifiers all on one chip. It is packaged in a 1-piece mold package. | |
Dial IC |
IC for detecting input pulses from the quick control dial. | |
Motor Driver- 1 |
M-1 motor control IC. This IC features a wide operating voltage range of 4V to 15V. | |
Motor Driver-2 |
"Smart Power"M-2 motor control IC. | |
Motor Driver-3 -PDB-E1 |
IC for controlling the M-3 motor which carries out high-speed mechanism charging. | |
SW-Lock IC - PDB-E1 |
IC for controlling the operation/non-operation of the SW-1, SW-2, and AE lock switches located on the Power Drive Booster E1. |
(4) Power Sources: -
 |
(a) Main power source, |
(b) Elimination
of backup battery Unlike the earlier EOS-1, the Canon EOS-1N doesn't required
a back-up cell inside the camera. Why would the camera requires a memory back-up
battery ? With the EOS-1, removing the Power Drive Booster E1 from the camera caused
the power to the camera to be cut momentarily. To provide enough time for the camera
status information to be stored in the EEPROM, therefore, the camera required a backup
battery to protect the operation sequence-related memory contents. With the EOS-1N,
however, the sequence memory function performed by the backup battery in the EOS-1
is carried out by a newly-developed microcomputer built into the EEPROM which writes
necessary camera operation data into the EEPROM at specific times (described in the
box below) to keep the sequence status continuously up to date, thus eliminating
the need for the backup battery. As a result, there is no need for the user to replace
any type of backup battery during the life of the camera, eliminating the worry of
eventual vulnerability.
Note: -However, if the battery is removed for replacement during film rewinding
or a long time exposure, there is possibility of camera mis-operation, and therefore
a need for caution against this type of handling for those applications.
 |
(c) Battery check Most electronic SLR camera has a battery check function for user to periodically check on the camera power status as once it is depleted, there is nothing you can do. Modern SLRs are generally very power thirst and it is a good practice to keep a spare for important assignment. The battery check function in the EOS-1N is a function which monitors the remaining capacity of the main power source. However, the popular |
symbol is not used in the EOS-1N, instead, a more delicate monitoring
system is employed in the EOS-1N. Like the EOS-1, the battery check function is activated
by pressing the battery check button inside the palm wing door. A resistor is used
for the battery check function's current-drawing load, and the result of the check
is displayed on the external LCD panel. The battery check display and the meaning
of the indications are shown in Table below this page.Even if the battery check display indicates state "4" (see below), correctly exposed pictures will be taken as long as the shutter releases. However, before a power-consuming operation such as film loading, shutter release, film winding or rewinding, the camera automatically checks the battery level and prevents further operation if the battery is found to be exhausted. If this occurs, "bc" blinks in the LCD panel.
Battery Condition and Display Indications:-
| Battery status | LCD panel indication | Meaning |
| 1 |  +  |
Battery is maintaining in an excellent condition state |
| 2 | + |
Battery is still usable, but have a new battery handy. |
| 3 |  |
Battery will depleted soon |
| 4 | |
Battery is exhausted or installed battery is not workable. Replace with a new one. |
 |
 |
 |
 |
Please take note that even if the
battery indicator blinks or does not appear in the LCD panel during battery check,
exposure will be correct as long as the shutter releases. When the battery power
drops below a certain level, film advance and rewinding stop operating and “” blinks in the display. Film winding automatically resumes after a new
battery is loaded. To resume rewinding, press the film rewind button (
).
Note: -More information on how-to check and installed power cells and other related info is available at the Basic Info section. Relative: Various options on Power Sources for Canon EOS-1N
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| Back | Index Page The Canon EOS-1N
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Back | Main Index Page The Canon EOS-1
Series Professional SLR camera
Background and Various Issues
| The Basic
Features &
various Setup
Manual &
Auto Focusing |
Metering Systems | Exposure Control | Viewfinder
Optical
System Flash Photography (with Speedlite 540EZ extension & Selective info on Canon TTL Flash Models:-160E | 200E
| 300EZ | 300TL
| 420EZ | 430 EZ | 480EG | Macrolite
| Other non-TTL Canon flash model
Reliability Issues:- Body Chassis | Shutter Unit | Electronic Circuitry | Film Transport & film handling Secondary Functions:- Custom Function Part One | Part Two | System Accessories:- Film Back Options - instruction for Command Back E1 | Macro/Close Up Part one | Part two and Part III Flash for Macro-Photography | Power Sources -BP-E1 | PDB-E1 | Focusing Screens | Remote Control with Wireless Remote Set LC-3 | System compatibility
Variants of Canon EOS-1N:- Canon EOS-1N RS | Canon/Kodak Digital DCS-1, 3 -5 & 520/560 Series | Full Technical Specification | Main
Reference Map / Nomenclature
| Resource Centre:- Comparative Charts between EOS-1 &
EOS-1N / or with
its active Competition(s) (Nikon); Quick Operational Reference Card (278k Gif File);
Listings of 7-segment
digital numbers/letters
appeared on LCD display panel/viewfinders (HTML page); External Link:-Instruction Manual (3.3MB
PDF file applicable for both Canon
EOS-1N (RS). | Using EOS system for your photography | Bots & Nuts of EOS System - by Philip Chong |
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