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This project comes in three primary parts:
 -The schematic (gEDA/gaf .sch)
 -The PCB design (gEDA PCB .pcb)
 -The firmware (C source code + Intel HEX)

This document includes information on the general function, the schematic and
the PCB design (with part list). For information on compiling and flashing the
firmware, see INSTALL.

timelapse is a device that allows automated time-lapse photography (i.e.
taking photos at regular intervals) on digital cameras that do not have such a
feature built in. The camera is required to have an external trigger input; at
least on Canon EOS cameras, this takes the form of a 2.5 mm audio-style jack

The basic operating procedure is as follows: the user inserts the trigger
cable into the camera, turns on the time-lapse trigger, enters the required
timing characteristics and repetition count, presses "OK", and the camera will
merrily fire away using these parameters.

A less terse user guide:
 (1) Insert the trigger cable into the camera and turn the camera on.
 (2) Turn on the time-lapse trigger. You will be presented with two options:
     pressing OK activates the trigger, and pressing CANCEL allows
     configuration. Press CANCEL.
 (3) The first configuration option is the LOW time; this is the time to wait
     between pulses. You can enter a time between 1 ms and 999999.999 s
     (roughly 11.5 days). Use the Up and Down buttons to change the current
     digit and the Left and Right buttons to change the selected digit. When
     done, press OK.
 (4) The second configuration option is the HIGH time; this is the duration of
     the pulse. This allows, for example, changing the exposure time if your
     camera supports doing so. The acceptable range is the same as with the
     LOW time.
 (5) The third configuration option is the number of times to repeat. This can
     be any number between 0 and 9999, inclusive. If 0 is entered, the trigger
     will repeat indefinitely.
 (6) Finally, you are asked if you wish to save the settings. Pressing CANCEL
     will discard all changes. Pressing OK will save your changes to the AVR's
     EEPROM. After either saving or discarding the settings, the trigger will
     reboot and re-read the settings from ROM.
 (7) With the trigger rebooted, you are again presented with the options from
     step 2. Pressing OK will activate the trigger.

N.B. while timelapse supports high and low times of 1 ms, it is likely your
camera does not. In particular, pulse widths (HIGH times) of less than 10 ms
or so are likely to be ignored. Moreover, tests with a Canon EOS 450D show
that using timelapse with auto-focus is not very reliable; this is especially
true in bulb exposure mode. If you are having problems with missed photos, try
switching to manual focus.

Finally, it should be noted that the total period is equal to the sum of high
and low times. For example, to take a picture exactly every ten seconds, you
should make sure the sum of high and low times is 10 seconds (e.g. LOW 9.900
s and HIGH 0.1 s).

To view or edit the schematic, gschem[1] is required. gschem is a free
software schematic editor, and is part of the gEDA project[2].

The schematic is, at the time of writing, contained in a single file
(timelapse.sch), which should be found in the same directory as this document.

The schematic contains symbols from the gaf (gschem and friends) standard
library, plus several symbols by Penguin Development. All symbols are
embedded; it is thus not required to download any additional ones.

To view or edit the printed circuit board design, PCB[3] is required. PCB is a
free software circuit board design program and is part of the gEDA project[2].

The included circuit board design (timelapse.pcb) is a rough working
prototype, although not fit for production use (the present design cannot
properly be placed into a case; I wish to do a full redesign at some point in
the future).

The working prototype is designed to be built at home by hobbyists and
therefore does not require of through-plated vias. Additionally, through-hole
components only have connections to traces on the top side if they are easy to
solder there. The board has two layers and requires a 40 mil (or 1 mm) drill
bit. The smallest components have 0402 footprints (0.4 by 0.2 mm).

The board design uses footprints from PCB's standard library, several symbols
by Penguin Development, a symbol by Cory Cross[4] and one by DJ Delorie[5].

The current design has some problems:
  (1) The ISP header (J1) is too close to the Cancel button (S6), meaning the
      programmer's connector may not fit properly.
  (2) The sleeve wire of the output cable is too thick to fit through a 1 mm
      hole (CONN1, pin 3).

(1) can be solved by a variety of means; pressing down on the connector while
programming may work. Another option is to use a header with slightly longer
pins. Finally, you could also flash the AVR *before* placing S6. If you do not
have through-plated vias, however, this will cause C3 to be disconnected from
ground (which *probably* won't cause any problems), as it uses a connection to
one of the legs of S6. (2) can be solved by some jury-rigging, e.g. by
soldering a thinner wire onto the end of the cable assembly and soldering the
other end to the board.

Notes and tips for building the PCB:
  (1) If through-plated vias are not used, solder a wire through the via
      holes. Connect all vias *before* placing any components.
  (2) U3 requires a large pad connection. It is impossible to connect this
      properly using a soldering iron; hot-air soldering or a reflow oven
      should provide the best results. If these options are unavailable,
      solder only the tab to the pad to provide the necessary electrical
      connection. Note that this reduces mechanical strength and
      power-dissipation capabilities.
  (3) Some vias are placed underneath components. If these vias stick out too
      much, it will be difficult or impossible to properly connect the
      components. In this case, a small rotary grinder may be used to slim
      down the vias' height above the board.

| Name                | DigiKey[6]/           | QTY | Refdes |
|                     | DealExtreme[7] part # |     |        |
| C1608X5R1E334M080AC | DK 445-5143-1-ND      |   1 | C1     |
| CC0402JRNPO9BN200   | DK 311-1417-1-ND      |   2 | C4, C5 |
| CC0402ZRY5V8BB104   | DK 311-1375-1-ND      |   2 | C2, C3 |
| RC0603FR-071KL      | DK 311-1.00KHRCT-ND   |   1 | R2     |
| RC0603FR-0710KL     | DK 311-10.0KHRCT-ND   |   1 | R3     |
| RC0603JR-07330RL    | DK 311-330GRCT-ND     |   1 | R1     |
| RC1206JR-07150RL    | DK 311-150ERCT-ND     |   1 | R5A    |
| 9C-4.096MBBK-T      | DK 887-1828-1-ND      |   1 | U2     |
| ATTINY2313A-SU      | DK ATTINY2313A-SU-ND  |   1 | U1     |
| UA7805CKTTR         | DK 296-20796-1-ND     |   1 | U3     |
| TLP222A(F)          | DK TLP222AF-ND        |   1 | U4     |
| CA-2204             | DK CP-2204-ND         |   1 | CONN1  |
| FSM4JH              | DK 450-1650-ND        |   6 | S1..S6 |
| M20-9983646         | DK 952-2132-ND        |   1 | J1..J4 |
| WP710A10LID         | DK 754-1610-ND        |   1 | D1     |
| 3365/16 300SF       | DK MC16G-5-ND         |   1 | [J3]   |
| PV36Y103C01B00      | DK 490-2913-ND        |   1 | R4     |
| 2-1658527-0         | DK A113153-ND         |   1 | [J3]   |
| BS3I                | DK BS3I-ND            |   1 | B1     |
| QPC02SXGN-RC        | DK S9337-ND           |   2 | J2, J4 |
| (Slide switch)      | DX 124577             |   1 | S8     |
| (LCD module)        | DX 121356             |   1 | [J3]   |

[1] http://wiki.geda-project.org/geda:gaf 
[2] http://www.geda-project.org/
[3] http://pcb.geda-project.org/
[4] http://www.gedasymbols.org/user/cory_cross/footprints/HC49smt.fp
[5] http://www.gedasymbols.org/user/dj_delorie/footprints/nvsemi/d2pak.fp
[6] http://www.digikey.com/
[7] https://dx.com/