EEVblog Electronics Community Forum
Products => Thermal Imaging => Topic started by: Cat on October 25, 2019, 01:33:50 pm
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Hello everyone, I finally decided to document my little project here.
Short story:
I have a Tamarisk 320 and want to get thermal images, unfortunately there is no feature board with analog video out and the IP-Cam part is broken.
Only the digital signals of the Tamarisk are available (LVDS, CameraLink ...) which I can't interface with. So I want to design my on DAC-Board.
Long story:
Bought the insides of an thermal IP-Cam from eBay a few years ago as untested but probably working. The optical appearance was fine but of course when the device finally arrived it was dead. :palm:
The IP-Cam part is from Leopard Imaging Inc. (https://leopardimaging.com/), it is a stack of different PCBs: Powersupply (PoE or 12V input), Interface (Ethernet PHY, RTC), CPU (TI DaVinci CPU, RAM, Flash) and Interposer (CPLD) to interface the Tamarisk.
The connectors to the outside world are ethernet with passive PoE, 12V power in, analog video out (from the CPU) and a reset/config switch.
To be continued...
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When supplying 12V to the boards some LEDs light, voltages are present and the Tamarisk moves its FFC-flag. The CPU gets slightly warm... everything seems normal but there is no output signal present.
Nothing on the debug UART (which should display messages during booting of the OS), no link-detect pulses on ethernet (PHY is not configured) and no video out.
The seller was a friendly chap which supplied replacement interposer and CPU boards to me, unfortunately the CPU bord needs firmware to do anything. The friendly support from Leopard Imaging supplied me sources and a compiled firmware I could flash, so I now have a working CPU board.
Again I had no luck because it's overflowing the debug UART with error messages.
ERROR (drv_imgs_DRS_Sen i2c_transfer(0x4d, 0x18)
sor.c|DRV_DrsWrite|161): DRV_Drs i2c_transfer(0x4d, 0x20)
Write()
ERROR (drv_imgs_DRS_Sensor.c|DRV_DrsR i2c_transfer(0x4d, 0x20)
ead|194): DRV_DrsRead()
#######LCR data = 0x0
The messages arrive so fast my USB-UART converter can't keep up with the data and looses some characters. Also the webserver is running for a few seconds but is then probably slowed down unusable because of the debug messages. The messages indicate a problem with the communication to the Tamarisk and the Leopard Imaging support suggests to set the parameters on the Tamarisk with the DRS tool.
So now to the Tamarisk part in the next post.
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The partnumber on the Tamarisk suggests it has a 40° lens, 60Hz PAL and had a feature board when shipped :(
Only slight corrosion indicates it was already used, otherwise it looks fine and probably running happily because of the FFC-Flag events.
To get a serial connection to the Tamarisk I used the interposer and soldered fine wires to the appropiate pins. The samtec-connector to the Tamarisk has 0,5mm pitch so my soldering looks terrible under the microscope :)
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After a few tries I could get the serial interface to the Tamarisk running and communicating with the DRS-tool. I tried the suggested settings from LI, but it didn't change anything.
The pixel-map (Tamarisk Pixel Map.cpm) could be downloaded from the camera but consists of 19200 times "F". I Don't know if this is a good or bad sign...
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What's next? I want to know if the Tamarisk still outputs a thermal image. Because I'm more hardware oriented I want to get a feature board for my Tamarisk. It's easier for me to display analog video than getting a camera-link framegrabber or the IP-Cam boards to work properly.
I could buy a new original DRS feature board for a few hundred $, but only to plug it in and see a dead FPA is not worth it in my opinion.
If anyone has a feature board I could borrow to test, please PM me :)
Also good pictures of the feature board would be highly appreciated.
I want to design and build my own feature board. The Tamarisk manuals give a few hints but it's sparse around the DAC-stuff.
So what do we know from these documents?
The 5V to 18V regulator utilizes a Texas Instruments TPS61170DRVR
.
The TPS61170 is probably used as SEPIC (Buck-Boost) converter. There are two TPS on the feature board, both with the two inductors, coupling cap and diode needed for SEPIC operation.
Why there are two of them I don't know.
AD9705 digital to analog converter
The AD9705 is a 10 bit 175 MSPS DAC for analog video. The Tamarisk delivers 14 bit BDSI-data, so hopefully the lowest 4 bits can be omitted.
Sync and clock is supplied from the Tamarisk as well.
USB interface utilizes FTDI’s FT232RQ
Typical USB to UART bridge, nothing special.
RS-232 interface utilizes Linear Technologies’ TC2801IDE#PBF
UART to RS232 level shifter, again nothing special.
Now the real questions begin: How to design in the DAC?
The output is differential and of high impedance. How do I get the RS-170 video levels and how it is done on the feature board?
There are only a few low-res pictures of the feature board available online:
https://www.sierraolympic.com/images/uploads/products/Tam320_1_Back_300x321.png (https://www.sierraolympic.com/images/uploads/products/Tam320_1_Back_300x321.png)
https://www.sierraolympic.com/images/uploads/products/DSC_5413-2.png (https://www.sierraolympic.com/images/uploads/products/DSC_5413-2.png)
https://www.sierraolympic.com/images/uploads/products/DSC_5411.png (https://www.sierraolympic.com/images/uploads/products/DSC_5411.png)
In the first picture below the DAC is in the middle of the right side ("TxDAC" marking), above is the UART to RS232 level shifter.
I assumed at first the 6pin component below the DAC is a voltage regulator. There are tantalum capacitors nearby but the pinout does not match anything I know. After some time I found a matching part: ADA4430-1 which is a Ultralow Power Video Filter (with amplifier/driver for 75Ohm loads).
Now even more questions arise: Is the DAC AC or DC coupled to the amp? What bias and settings are needed for the DAC?
This is the current status of my little project. The next step would be to design my own feature board with the connector to the Tamarisk, power supply, ADC, Video-Amp, and USB to UART bridge and mybe a camera-link connector.
If there are any news I'll let you know.
regards
Cat
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Tamarisk outputs camera link and parallel 14 bit video. Did you get it working?
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Tamarisk outputs camera link and parallel 14 bit video. Did you get it working?
YES!
TL;DR: Build my own feature board and have now analog video out 8)
Thanks to the pictures from Ultrapurple (https://www.eevblog.com/forum/thermal-imaging/new-toy-occulus-ti-w-pan-tilt-any-ideas/msg2771552/#msg2771552) and the official documentation the feature board could be reverse engineered and I decided to build my own.
My feature board includes the DAC, video filter/driver and levelshifter for the serial connection. I did not yet measure the video output with the scope so the resistor values for the DAC might need some fine tuning to get the right voltage levels. The LEDs on the back show the operation of the FFC-flag. Serial communication is possible with a standard USB to 3,3V LVTTL adaptor.
Manufacturing was straight forward, solderpaste (with Pb ;) ) was applied with a stencil and after placement of the components by hand the PCB was reflowed in a modified pizza oven.
The most difficult part was aligning and soldering the 0,4mm finepitch Samtec-connector but after one test run I got a decent result.
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Excellent work :-+
Fraser
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Wow, this is fantastic!
This remembered me of a (dead) DRS Tamarisk a bought some time ago just for the lens which I wanted to test at some point - maybe I can ask you some questions regarding interfacing with the core.