Latest revision as of 15:22, 16 November 2014

Introduction

In order to port CHDK, you need a copy (dump) of the original firmware from the model you are trying to port. This page explains various methods of obtaining a dump.

For most cameras the Canon Basic Dumper script is easiest and should be all you really need. The other methods mostly of historical interest.

Once you have a dump, see Adding support for a new camera.

Canon Basic script

See Canon Basic/Scripts/Dumper. This is the recommended method, which has been used for most cameras since it was discovered in 2010.

Udumper

NOTE: This method will not work on recent (since 2009 or so) camera without modifications.

CardTricks is a graphical utility which includes udumper and a gui to prepare the card.

You could also use UDumper without cardtricks. See Udumper and some related forum threads:

WIF Loader

The method is to make/adapt the WIF loader. The base for developing it is an original firmware updater to similar camera models. As this loader has the functions to work with files, this way allow to save a dump of original firmware to SD-card. The main problem of using this method is that you have to pass all initialization stages of original firmware in order to be able to write to flash card. Used with: A620, A630, A640, A710, S2IS, S3IS.

Hardware-software solution

NOTE: The method described here is a lot of work and no longer necessary - use the Canon Basic Dumper. It has been left here for historical interest and out of respect for the effort of those who created it in the first place.

The firmware for the following models was obtained using this method: A610, A700, A540, G7, SD630, A570IS, SD300, SD450, SD500, A560, SD870, SD1000, SD1200IS, S5IS, A720, G11.

This method is based on the 'blinking' of the original firmware through a led of the camera. You have to make a receiver (photodiode or phototransistor), the software to write a dump, decoder and a tiny firmware which outputs camera's firmware through the led. The receiver can be connected to serial port (you need to emulate the UART in the camera in this case) or a microphone input.

Note: Many people have had trouble trying to obtain a photo-diode or photo-transistor for this task. Do you have an old ball-driven mouse in a junk-box? Each X and Y axis is read by the rotation of a notched wheel passing through the light-path between IR LED (transmitter) and a photo-diode detector. The optical device you need is easily salvaged from that. Caution: Many of the mouse photodiodes are ONLY sensetive for infrared light. These photodiodes can not be used for firmware dumping, because they can not "see" the LED light from the camera.

Using soundcard input

I used the microphone input. All necessary files (with sources) you can get here.

The scheme I used:

    / \
   |   |
    \ /        +-----------+
   +===+       |           |            |----\
   |   |-------+       ----*------------|     |
   |===|            ----*---------------|     |
   |   |                |               |----/
   |   |----------------+
   |   |                       phototransistor 
 +=======+                     BPW96C or equivalent
 |       |

 3.5mm plug
 to mic-in
 of soundcard

The transmitting protocol:

Header (3600 bytes) - "0123456789" sequence for visual control of data.
Blocks - 4096 blocks of 1K data.

Address (4 bytes) - address of the current block.
Data (1024 bytes) - piece of firmware.
CRC16 x 2 (4 bytes) - CRC16 of block (repeated twice).

Each byte is encoded in the following way:

,where:

Spacing between bytes
Spacing between bits
Wide pulse - logical "1"
Narrow pulse - logical "0"

The usage flow:

Connect the receiver to the microphone input of sound card.
Run a recording application (I used Adobe Audition) with the following parameters: 96KHz (it's adjustable), 8 bit, mono.
Direct 'blinking' led at the receiver (BPW96C).
Start the recording. Start transmition of the 'blinking' firmware.
Wait for process to be finished (1-7 hours depends on speed chosen). The camera will be switched off at the end.
Save the data to the PCM-file (8-bit unsigned raw data, not WAV!).
Process the file by 'adc.exe <filename>'. You will get 'dump' file.
Run 'dec.exe'. You will get 'dump.dat' file. This file is the firmware.

Speed/signal adjusting:
It may be required to do some adjustments depended on camera/led/receiver used. The main idea is to get 'readable' signal as shown on the picture above.
Here the values for certain speeds and leds for A610:

A610 - AF beam, FAST (9230 bod) [96KHz]
--------------------------
fw:
  #define DELAY_SYNC   45
  #define DELAY_SPACE  50
  #define DELAY0       1
  #define DELAY1       25
decode:
  #define LEVEL_THRES_HI  0xA0
  #define LEVEL_THRES_LO  0x80
  #define LEN_SYNC        5
  #define LEN_SPACE       1
  #define LEN_0           1
  #define LEN_1           6
A610 - AF beam, SLOW (2500 bod ) [96KHz]
-------------------------
fw:
  #define DELAY_SYNC   400
  #define DELAY_SPACE  100
  #define DELAY0       100
  #define DELAY1       200
decode:
  #define LEVEL_THRES_HI  0xA0
  #define LEVEL_THRES_LO  0x80
  #define LEN_SYNC        40
  #define LEN_SPACE       5
  #define LEN_0           12
  #define LEN_1           24
A610 - BLUE_led (1600 bod) [11KHz]
-------------------------
fw:
  #define DELAY_SYNC   400
  #define DELAY_SPACE  175
  #define DELAY0       150
  #define DELAY1       350
decode:
  #define LEVEL_THRES_HI  0x90
  #define LEVEL_THRES_LO  0x70
  #define LEN_SYNC        7
  #define LEN_SPACE       1
  #define LEN_0           1
  #define LEN_1           4

Serial port download solution

You can download (blink) the firmware using your computer's serial port instead of sound card as input device. You may need a photodiode connected to serial port according to the following schematic:

The photodiode used is a generic one. You may need to test the distance to the camera's AF LED which fits you better, mine worked properly at about 20cm (8 inches) away, YMMV. (side info: you can hardly see the LED blinking because it is very fast, but it is still perfectly readable by the photodiode, so do not worry). The resistance in the circuit shown above has got 10 kOhm. Depending on the photodiode the resistance should also have 200 Ohm for best use.

You also need the camera blinker and serial port loader programs. You can find the original version written in Pascal here. An other converted version to Java with CRC16 is available here.

The first version contains these two parts:

Camera: PS1.fir and PS2.fir which are the camera's blinkers for Canon Powershot G7. This has been split in two for easer repetition of downloading in case of failure (it takes around 40 minutes each to download for G7). I guess you can use your camera's own blinker here instead.
PS: load.exe which is the serial receiver program for Windows. The syntax is

load <serial port #> <dump filename>

The second version contains these two parts:

Camera: Source code main.c which have to build for your camera. See details in Readme.txt.
PC: Compiled Java program Load.class. See details in Readme.txt.

Alternatively to load.exe / Load.class you can use realterm for both monitoring the serial port and capturing the file at the same time. Make sure you configure it like this:

Display tab: Hex + Ascii, set "Scrollback" for 2000 lines or so, increase the rows count too.
Port tab: 9600 8N1 (transmission speed 9600 bits per second, 8 bits, No-parity, 1-stop pulse at the end of byte), set your serial port number and don't forget to click on "Change".
Capture tab: the filename you want to dump to, untick "Direct Capture" if you want to watch it going.
Pins tab: Make sure to "Clear" DTR(4) (Clear Data Terminal Ready-signal used if "hardware hand shacking" is used during transmission).

While capturing you can see the file grow and the speed rate in the status line at the bottom. It should be a figure around 800 CPS (characters per second).

The real action:

Connect the photoreceiver to the computer's serial port.
Properly align AF led and the receiver photodiode.
Start load.exe. in a command prompt. You have 10 seconds to start blinker or it will timeout. Alternatively: Press on "start overwriting" to start capture in realterm, there is no timeout here.
Start the blinker "firmware" in the camera following the usual firmware update procedure. You should see the AF light turn on and load.exe writing data to terminal...

C:\> load com1 firmware1.fir
Received1kbytes.
Received2kbytes.
...
Received2048kbytes.

load.exe will timeout after 10 seconds at blink's end. For realterm you'll need to manually stop capturing when the AF led comes off. Once done, reload your camera's battery. For G7 you may need to repeat the above procedure using PS2.fir to get the firmware's second part. Open the downloaded firmware files in a HEX Editor and cut off the lead in information (.....xx xx xx begin) and the load out (end.). Now you have two files with all the necessary data in it. To join two files just do 'copy firmware1.fir + firmware2.fir Firmware.bin' and you have single firmware file in your hands.

An detailed description of the SX200 blinking process with the used hardware and software is here: Blinking the firmware to the RS232 interface.

The wired solution: You can also go hardcore and open the camera and look for the LED connections (you will not need the phototransistor) to get a more reliable connection. If you are brave enough you can find the instructions here.

Firmware

ROM start addresses

Known ROM start addresses are:

0xFF000000	Used by some cameras starting in 2011
0xFF810000	Most 2010 and earlier S-, SD-, G- and some A- series
0xFFC00000	Mostly older A- series

Changes: Obtaining a firmware dump