FEATURE EMBEDDED SYSTEMS THE QSEVEN STANDARD
Zeljko Loncaric, Marketing Engineer, congatec AG investigates how the latest MIPI CSI2 interface is proving an idea fit for embedded applications
D
evice manufacturers stand a lot to gain from adapting cheap consumer
technologies to the embedded market. The latest such technology transfer example is the MIPI CSI2 camera interface which connects the cameras of tablets and smartphones with the internal electronics. Embedded manufacturers can use it to cost-effectively equip their devices with megapixel cameras.
MIPI INTERFACE The MIPI interface has established itself as the de facto standard in the smart phone industry. The key advantage lies in the high production volumes and hence the extremely low cost of camera modules with a MIPI CSI2 interface. By standardising the hardware and software interface, camera manufacturers and third-party providers can develop and implement appropriate drivers for popular operating systems. This eliminates the tedious task of driver integration and the system integrator no longer needs to create any special board support packages for this. The major chip and FPGA manufacturers have recognised this and many of their processors now come with an integrated MIPI CSI2 interface. Next to most manufacturers of ARM chips for mobile phones and tablets, this also applies to Intel’s Atom E3800 processor family. Another advantage is that the transmission rate can be scaled to the required bandwidth. This saves a lot of power, which is particularly important in mobile devices. At the same time, it is possible to transmit high resolutions such as HD 720p and even full HD 1080p with uncompressed frame rates of 60fps and more. These performance features make MIPI CSI2 ideal for Qseven-based camera applications, particularly in mobile devices.
WHAT ABOUT USB AND ETHERNET? Upon closer inspection, the two obvious alternative interfaces – USB 3.0 SuperSpeed and Gigabit Ethernet – prove to be unsuitable, at least for mobile devices.
Fig 1:
The conga-QMX6 Qseven ARM module with Freescale
i.MX6 processor has been providing a MIPI CSI2 interface since its first launch in 2013
The maximum bandwidth is significantly
lower, at least for Gigabit Ethernet, while power consumption is significantly higher for both alternatives. What is more, any non- MIPI solution would first require the development of the necessary software stacks and drivers. Anyone prepared to put in this extra effort would certainly get a better result with a solution that connects directly via PCI Express or a SATA interface. For larger distances from the camera, a
Figure 2:
Embedded application with congatec MIPI CSI2 camera, Qseven ARM module, MCTX
multimedia baseboard and two independent LVDS displays
possible alternative to a purely internal solution is a bridge between USB 3.0 and MIPI CSI2. Besides higher power consumption and significantly greater total hardware costs, it is important to remember that this also blocks the often only USB 3.0 interface on the module for other applications. Data backup or software updates via USB 2.0 would in that case take considerably longer.
The Computer-on-Module (COM) concept has established itself over the last ten years on a broad scale. Here, the highly integrated, complex and expensive parts of a computer are implemented on a module and pre-integrated by the module supplier. System integrators and OEMs can focus on their core competencies and “only” need to develop a matching carrier board which contains their know-how in the shape of specific peripherals. Diversification is increasingly achieved via the software. With standardised COMs it is possible to adjust the required power precisely and to quickly integrate new hardware as soon as it becomes available. For ultra-compact and mobile systems up to 12Watts maximum power dissipation, the Qseven standard – defined with the support of embedded specialist congatec AG and now maintained by the SGET association – is well established. This is not least because it was the first, and for a long time only, standard to support both x86 and ARM architectures. Despite the availability of a large number of processors, the Freescale
i.MX6 family has a great following amongst all module manufacturers. A reason for this popularity is that it is a
complete family of pin-compatible processors with one to four cores that include a choice of graphics and multimedia capabilities with LVDS and DisplayPort. Many of the interface options defined by Qseven are already available on the chip: PCI Express lanes, CAN, SATA, USB, I2C bus, watchdog, MIPI CSI2 interface. Components also come with long-term availability of ten years and meet embedded or industrial standards. What was originally a proprietary extension,
“These
reference designs are out-of-the box
which means they can be used as they are, or modified to meet the wishes of target system development engineers ...”
has since been standardised by the SGET at the request of the Qseven community. For professional applications, congatec partner MCTX has equipped its Qseven/ARM multimedia carrier board MX-Q7- MM1 with the conga-QMX6 module and a MIPI CSI2 compatible camera. Potential applications include medical equipment,
monitoring tasks, authentication and access control;
personal and facial recognition, intelligent lighting systems and all kinds of webcam and intercom functions (e.g. video telephony).
congatec AG
www.congatec.com 01332 872201
28 JULY/AUGUST 2015 | ELECTRONICS / ELECTRONICS
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