Products > Thermal Imaging

Two new acquisitions by Fraser - for fans of older professional thermal cameras

<< < (4/5) > >>

Bill W:
Another popular DIY control method would be using TV remote control signals.
Hardware encoder in the handset and put the decoder in software in the micro(s)

Bill

Fraser:
Bill,

Yes I have seen the Philips RC5/6 IR control system integrated into many products. It was well documented and understood, so an obvious choice for OEM’s. I have also seen the venerable old SL490 IR encoder used in simp,e control applications as the matching decoder IC was an easy integration into a system. I have seen the SL490 encoder also used in wired remote controls using a simple Ignacio and 0V communications cable that also provided power to the remote controller. The SL490 signal was superimposed on the DC feed and recovered using a simple circuit before passing to a microprocessor.

I remain hopeful that the NightSight is using a very simple resistor network type remote controller and the ADC’s in the MCU. If not, it will be head scratching time and I will need to consider other possibilities. I will learn more once I trace the unidentified wires to their destinations as if it is the ADC pins…..great, if a GPIO pin…damn it likely has an encoder chip in the remote control. The MCU has integrated RS485 connectivity and if that is being used, I am in trouble as I have no way of knowing the command protocol and reverse engineering the firmware of a MC68HC705 could be a challenge !

My one bit of light in this remote control situation is a passing comment by a 2000B owner who stated that the remote control joystick he had was passive and so simple that it could be easily duplicated.

Fraser

Fraser:
I now know how the NightSight is controlled !

When reverse engineering a piece of electronics we often hope for a simple and logical approach to the design and that is what I was hoping for in this case. Sadly I was disappointed on this occasion as, despite the camera not having a PC controlled variant, it uses RS485 for its communications. I traced two of the unidentified wires to the small MCU PCB located inside the head assembly adjacent to the BST core. They did not directly terminate anywhere on the MCU so I removed the PCB for visual inspection. On the rear of the PCB there are a few IC's, amongst which is the LTC485. The two unidentified wires terminated at pins 6 and 7 of the LTC485......... a RS485 transceiver IC :( I knew then that my hopes for a very simple passive remote controller were dashed. The LTC485 drives pin 50 (RDI) of the 68HC705B5 MCU. To determine the communications protocol I would have to reverse engineer the firmware and that is if the IC does not have firmware protection in place. That comes under the "too much work" heading for me at the moment. I could fire up the BST core and get it working without too much bother but this core is little different to those that I already have in the EEV Argus 2 and Talisman Wasp cameras so there is little to be gained. For now, this NightSight 200 camera is a nice addition to my collection and part of the Texas Instruments/Raytheon vehicle borne thermal camera story. I have no regrets about buying it and it is in very nice condition. Just a pity that I cannot get it "rocking and rolling" with a simple remote controller.

I attach pictures of the second MCU PCB.

I must now return to other, higher priority, matters and then the Bullard Eclipse will be getting a full service and restoration.

Fraser 

Fraser:
I have not forgotten the third unidentified wire that terminates on the lower MCU PCB in the base of the Pan & Tilt head. I will trace that to its destination another day when I have more time to disassemble the PCB/rotary contact assembly from the casing. I am not expecting that wire to save the day though.

Fraser

Bill W:
that is a real shame Fraser.

You could try sending an ASCII 'U' to the head at 9600 and see if it goes up.

Navigation

[0] Message Index

[#] Next page

[*] Previous page