Mentioned in the previous post, the PCB’s arrived ahead of schedule last week, well done pcb-pool.ie . All looking good, I need to gather the remaining components together, ready for a re-flow process of all the top smd components.
The board will be mounted free or in a plastic enclosure. All cables will exit on the same side as the camera HDMI and USB ports.
Well the ASTRO pcb design has been sent to the manufacturer today. Its in some way is a leap of faith that the layout is correct and that it meets both physical and electrical requirements and that nothing has been overlooked. There is a big temptation to add every last function, but eventually, you have to let it go. Smaller connectors, a more efficient voltage converter and a smaller programming port have been added.
I decided for one thing, that the board would only be powered from the attached cable. This may seem odd because the camera is capable of powering the controller, however, on the ground, when things lock up (which they do frequently in the real world) it is good to be able to reset the system by pulling the power.
The camera can be run with or without its battery in place. I have it arranged that the remote handheld unit will power the board and operate the camera with a small internal battery. However, if the user connects an external power supply (9-15V @2A), the handheld unit will also power the camera without the camera battery. An option to remotely charge the camera battery instead, can be provided.
The initial plan is to utilise Ethernet cable with RJ45 connectors between the handheld remote and the camera. Two pairs for DC power and one pair for RS485. Audio and composite video is available via 10-pin USB if required and the remaining pair may help in this.
24 hours into production the PCB maker has posted a graphic illustration of the production stage – Exposing the PCB.
And now the Tin Stripped process is completed.
Solder mask – process cured 31/3/2017
The manufacturer posts these images as the board is being processed. This helps spot mistakes that might cause an issue at a later stage. So far all looks good, there are some issues concerning silk screen text placement and size. Two common vias have merged but is not a problem in this case. Resistor and capacitor outlines have not printed either.
My previous Hero4 projects have all required fitting an interface board in the camera to achieve various functions. This latest is now a plug-on module which uses the 30-pin connector to interface to the camera. The following is a very brief specification.
Camera: Hero4 Black with firmware version v3.0 and above.
Functions: Power On/Off, Record On/Off, Default Mode Change.
Trigger: Opto-isolated input trigger
Power: 9-24V DC (Internal battery not required)
Data: RS485 9600 bps
Remote power and recording control with remote DC power options
Time lapse intervals longer then 60 seconds possible (requires an intervalometer)
Camera powered down during long Time lapse intervals reduces power requirement
Camera can be triggered to switch on and record (seconds time delay to start) via external sensors.
Operation and recording status can be received/displayed.
WiFi cannot be enabled via this unit (to the best of my knowledge).
Requires additional transmission paths to view images and audio.
Need access to camera to recover recordings.
Need access to camera to switch on WiFi if camera powers down.
The first PCB sample is currently being manufactured and an enclosure similar in size to the LCD backpac will be ready soon for testing.
A simple handheld button controller will be used to operate the camera over a single RS485 cable pair. The camera can be powered over a second cable pair from a suitable 9-24 Volt power supply or battery. Interfacing RS485 to a PIR movement device or an intervalometer for long interval time lapse use will be easy to enable via the remote unit. A opto-isolated input is provided to trigger programmable functions such as “Turn On – Take a Photo – Switch Off” or “Turn On – Record Video (2 minutes) – Turn Off” as possible options.
RS485 systems can provide control over a distance of 1200 meters. A basic system, using a multicore cable such as CAT5 Ethernet cable or multicore alarm installation cable it is possible to send and receive control data, supply remote power and view a composite video feed and audio channel without using any complex connections or equipment over 50~100 meters. A more complex system might use a fiber-optic or wireless system to transfer HDMI 1080p and the RS485 signaling.
Why do I not use the cameras WiFi to control and view the camera? There are at least two issues to consider. WiFi signal range is challenging in many real-world situations and unfortunately, when remote power is needed, the un-powered camera will not power up with WiFi enabled.
The above circuit’s are used to develop and test the software and hardware.
A paper printout helps focus in on any issues overlooked.
Update 11 April 2017 – PCB’s back from the manufacturer last week.
The first time I came across these connectors was while repairing a broadcast camera. The connector had to be removed each time the camera was disassembled and because the issue was intermittent, this was happening numerous times before the problem was resolved. As it happens, this final time was when a new problem arose with the camera, and led me to discovering how expensive a replacement turned out to be, but also just how wonderful technology has advanced in cabling and connectors.
The Micro IDT Coaxial connector is designed to connect 30, 40, or 50 circuits capable of supporting currents of 200mA on a connector with a 0.4mm pitch. Each cable is a micro coax type which provides excellent shielding and grounding between connectors which is not possible with other technologies such as FPC (flexible printed circuits) more commonly found. Another great feature is that the can be routed through gaps and flexible joints more easily and robustly. Cable size is AWG42.
Anyway, back to my problem. In not recognising the technology involved, I was less careful in disconnecting the connector at some point, and thus the fault occurred. A 10x magnifier was required to spot the damage. A single cable at one end of the connector was loose. At first thought, I assumed a simple repair could be made to reconnect the wire, however this is just not possible with theses connectors.
My warning, if you see these connectors in equipment you service, be extremely careful in how you remove and connect them.
I have no doubt that these will be used in more and more equipment due to the fact that they can be fabricated in house and because of the noise immunity and EMF characteristics they possess.
Each 42 AWG coax cable is approx. 0.3mm in diameter, it is silver plated with a 48 AWG silver plated copper Helicoidal screen. The sample I have appears to be a single inner core.
KEL Corporation (Tama, Tokyo) came to market with micro coaxial cable connectors (USL series) in 1998, according to a company history published on their website.
From published news June 2006 it is printed that Molex was the first company in the world to utilise IDT termination technology with coaxial cable on a pitch as small as 0.40mm (.016”).