astroccd.org

 

This is about how to make CCD camera based on ICX453AQ chip. This chip is also used in astro camera QHY8PRO.

• Camera resolution is 3000×2000 = 6Mpx
• Square pixel 7.8 x 7.8um
• 16bit ADC with CDS
• Color RGB Bayer
• 28.4 mm diagonal
• USB 2.0 interface
• Readout time is ±2s

The schematic is very simple, so anyone who knows how to solder and read documentation can easily repeat this model.

CCD Sensor Sony ICX453AQ unfortunately do not have datasheet in open access. So only reverse engineering helped to start the project.

This camera is based on FT2232H chip working in bit-bang mode, so no need to compile firmware or programming MCU. FT2232H allows to create 2 USB slave high speed devices(one for controlling camera, second for downloading image).

ADC – AD9826. Complete 16-bit Imaging Signal Processor with gain(0..63) and offset (-127 ..+127) control.

Vertical CCD Driver (Sony CXD1267) is controlled through shift register 74HC595.

Horizontal Driver is semi software. Based on dual high-speed MOSFET driver MAX4428 which contains one inverting and one non-inverting section. It drives 6 volts to CCD in counterphase. In future releases I think ill replace it with specialized ISL55111 chip.

Camera uses several power supplies (LDO/DC-DC) and runs from 12V PS.
2 LP2985-33 for FT2232 and shift registers
2 LP2985-50 for ADC digital and analog supply
1 LM2937-50 for DC-DC bias PS and nor-gate
1 AD3336ARMZ with 6 Volt for horizontal register
1 TPS65130 for -8/+15 for CCD bias supply
FT2232 have ability to be self powered, but currently it runs from VBUS.

The camera works in next sequence

1. Generating bitbang impulses (around 24Mb)
2. Write it to output buffer of FT driver.
3. Start dedicated thread for reading on 2nd part of FT2232
4. Send output buffer
5. Waitng for input to be finished
6. Forming image
7. Goto 2

Cam84 is forth (Cam81/Cam83/Cam8s) major revision of this project, based on Cam8s and currently just works out of the box. No need for cutting routes or making air wires or any other fixes.

Unfortunately it do not have built-in TEC controller yet. So you have to make it yourself.

Materials needed for the project:
CCD chip, PCB, Enclosure(Gainta G-107), Bill of materials.
2-3 hours of free time.

CCD Sensor:
Camera uses ICX453AQ sensor. As i said before there is no datasheet in open sources. So we used reverse engineering. I’m not 100% sure, but it seems to work.

This sensor is easy to get. Just buy used / not working Nikon D40/D50/D70/D70s. 95% that sensor will be in a perfect condition.
Than you can use this manual to get ccd pcb out of the body.

And that was the easy part.

The tricky part is to get sensor out of aluminum platform which is glued with very strong compound. There are 2 ways: the fast and the safe one 😉

Fast is to cut with hacksaw or dremel or smth else. Just make X-like cuts, remove aluminum and then remove remaining glue with a sharp blade. Use sandpaper after all.

And the safe method is to dissolve aluminum with NaOH or dissolve compound with DMSO (preferred). This will take up to 3 days.

Dismantling the camera to remove the CCD block is simple. I then used full anti-static precautions to remove the existing circuit board from the chip. THEN I bonded all the CCD pins with a single piece of wire, which I could loop around the carrier, so that when the carrier was removed, the chip would come free with the bonding intact.

A note on DMSO.
DMSO is a very heavy solvent, its boiling point is obscenely high, and it is very persistent. DO NOT WEAR NITRILE GLOVES if handling DMSO — it dissolves nitrile instantly, and passes DMSO and the nitrile straight through the skin. If you absorb DMSO through the skin, you will taste garlic for a week.

We placed the CCD, immersed in DMSO, in a safe place for around 4 days. At the end of the period, the CCD was completely free of the carrier.
Remove the CCD from the DMSO and wash off the solvent with acetone.

Your chip is now ready for the new PCB.

 

PDF is available for download HERE

PCB is a dual layer.

Top:

Bottom:

As you can see it has a lots of jumpers. They are on both power and signals lines. Made for easy debugging and current measurements in case smth goes wrong. In normal state should be closed.

Gerber files for production can be found HERE.

• Top layer
• Bottom layer
• Solder mask top
• Solder mask bottom
• Silk top
• Silk bottom
• Solder paste top
• Solder paste bottom
• DrillHolles (EXCELLON)

Note that Design Rule Check was completed with SeedStudio specification.

PCB Soldering:

First of all you will need to make a USB+Power Connector
Get «2X5P 2.54mm Pitch Dupont Jumper Wire Cable Housing Female Pin Connector», USB Cable and Power supply 12V (Camera will need max 500mA).

Connector pinout:

It’s really good idea to use selected pin as input for 12V, believe me. In case you put the connector upside down, 12V will go to VBUS and will be lowered to 3,3V. So no harm for FT2232. The rest 12V pin can be used as outputs for TEC or coolling.

The next goal is to solder FT2232H (IC7), EEPROM (IC6), U7 for power and all elements(resistors, capacitors, filters) dedicated to these ICs. WR# Jumper is also needed. After you finish, you can plug the board to your computer(no need for external power at the moment). A new device on PC should be detected. Win7+ will automatically download and install latest driver.
Note that i didn’t test camera on the latest drivers. I use CDM-2.08.24-WHQL-Certified

After you get 2 new devices, double click each of them and uncheck Load VCP.

Then you will need MPROG Utility and template.

Extract template from zip, launch utility, open extracted template and «Program all existing devices»

After that you need to unplug the board and plug it back. That’s all. Now ASCOM driver can work with the board. CAM84 compatible with ASCOM CAM8s driver. I assume that ASCOM platform is installed, so now you can install ASCOM driver for the camera. Actual ASCOM driver.
After installing run your favorite application for imaging(Maxim DL);

Setup Camera->Choose ASCOM->Advanced->Choose Cam8s;

And make a test shot. If everything is ok you can go to solder all other devices. If no, please double check that WR# jumper is on.

After the successful launch of FT chip, you’ll need to solder all the power supplies: U1-U6 (U7 goes with FT2232).
U1 generates -8V/+15V for the sensor(IC3) & Vertical Driver (IC5)
U2 generates +6V for horizontal driver (IC8)
U3 generates +5V for U1 & IC4
U4 generates +5V for analog power ADC
U5 generates +5V for digital power ADC
U6 generates +3,3V for IC2 & IC5

Double check all the voltages before placing ICs. Also good idea to measure current on +12V JP. Check supplies temperature, even by finger tip f.e. All the chips have to be cold. Also a good practice will be to use oscilloscope or multimeter with true RMS to be sure all power rails are correct voltage, steady and noise clean.

Next stage is to solder all the rest of chips except the sensor. We don’t need CCD at the moment, besides that its really hard to solder it out and its very sensitive to overheat. When you’ll finish — put all the jumpers on. And we are ready for pre test.

Plug it to PC and turn the power on. If there is no smoke — my congratulations 😉 All the supplies have built-in protection, but shit happens. Check that all chips are not hot. Repeat voltage and current measurements. There should not be drop downs or smth. If so — unplug and look for short circuit.

Assume that you have connected the device and there is no smoke, no heat and no noise coming out from the board — its time to run the test. Launch you imaging software, connect the camera and start continuous shooting. If you have oscilloscope you can check WR#/SL/SL2/SCK/SDA/S0/S1/S2 signals on jumpers and H1/H2/V1/V2/V3/V4 signals on CCD pads, they all have to be alive with some data. If everything is connected in a right way you should get an image full of noises. You can event touch capacitor C56 with a probe while exposing the frame and you should see a different noise patterns in response to this action.

If everything is OK — unplug and solder the sensor. Make couple shots to see if it reacts to the light bulb, put it into closed box to evaluate noise on biases.

If no — recheck signals, pads, joints, short circuits, etc until you find and fix the problem.

If you are not good at soldering tiny parts i recommend to watch tutorials on youtube.

EEVblog #180 — Soldering Tutorial Part 1 — Tools
EEVblog #183 — Soldering Tutorial Part 2
EEVblog #186 — Soldering Tutorial Part 3 — Surface Mount

Good luck!

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