[marknorton]

Splitting the Clam-Shell

This is pretty much all you can see without splitting the front and back castings. This involves peeling back the synthetic leather to expose 3 screws at each end. Remove them and the front and back halves of the camera separate.

Here’s a picture of the back half:

Clamshell Rear Internal.jpg

So this is the front of the DSP board which you saw in the first image. Things to note, starting top left and moving anti-clockwise:

- The interface to the M16C processor, the “camera” electronics.
- The infamous standby battery
- “Power Supply Central”. There are 6 separate power supplies from a MAXIM MAX1567 chip on the other side of the board. This is a highly efficient chip for generating the various supply voltages (which may be more than the nominal 3.7 volts of the Li-Ion battery) required by digital cameras in general and CCD sensors in particular. Each of the supplies uses an inductor (black) and a low impedance decoupling capacitor (brown).
- The SD card holder.
- The 30 way connector to the sensor board.
- The white power connector which connects directly to the battery.
- The white connector to the left hand push buttons (play, info, etc).
- The switch to detect if the base-plate is on.
- The white connector to the LCD display which of course sits behind this board.
- The USB connector.
- The white connector to the Menu button, the thumb wheel and the red LED.

In effect, this board is a self-contained computer with its own processors, user interface (Buttons/LED/LCD Display), dynamic RAM and non-volatile storage (SD card), USB interface and image capture interface.

This board shows how the camera’s electronics are split into two. The main camera electronics is all about initiating the taking of the picture, this part is all about either capturing the image from the sensor, processing it and storing it.

The interface between the two will allow a two-way exchange of information. Commands and data from the M16C will be about initiating image capture, sending data to the DSP board on lens type, light and exposure for inclusion in the EXIF; information back from the DSP will include a Ready/Not Ready status showing whether or not more images can be taken, information on the space available on the SD card and so on. There will also be support for sharing the settings of the main and set menus.

Remove the DSP board and we can now see the full back of the board:

DSP Board Rear.jpg

Here, you can see the main DSP used, the Analog Devices Black Fin processor along with 5 64Mb dynamic RAMS, each organised into 4 * 4Mb * 32 bits. Top left is the MAXIM MAX1567 power supply chip; centre top is the Intel PXA270C which is used for the user interface and a Xilinx FPGA (Field Programmable Gate Array) which effectively is a custom logic chip to tie everything together. A firmware upgrade changes the firmware in the Black Fin, the Xilinx, the PXA270C as well as the M16C.

Notice too the spare lands on the board which suggests the possibility of alternative parts being used or some, as yet undefined, future expansion. The white square is a bit of a mystery, I think it’s the audible “clicker”.

Looking at the edge of the board, I can see as least 6 imbedded layers in addition to the copper on each side, making 8 layers in all. It’s a very impressive piece of digital electronic design.

Removing the DSP board and this is what you see:

Clamshell Rear without DSP.jpg

You can see the three flex prints to the DSP board and the back of the thumb-wheel. The spring plate on the left is used to provide the detent for the thumb wheel.

I removed the right hand button panel to show you the buttons but left it at that because I did not want to get dust in the LCD panel. You can see that to get at the LCD panel to either remove dust or replace a scratched LCD screen is quire a lot of work, but even this is a walk in the park compared to what’s needed if the Lens Code sensor fails.

Button Switches.jpg