Camera technology is poised for a change in pace. The emergence of IoT, new business models like Google Ara, and evolution of wearable devices like Google Glasses will ensure this. We will require cameras that are smaller, can handle much higher bandwidths and at the same time consume less power. All this and more can be provided by MIPI CSI-3.
So How Is MIPI CSI-3 A Game Changer In Camera Technology?
MIPI CSI-3 is the next generation technology to MIPI CSI-2. While MIPI CSI-2 uses D-PHY (or recently enhanced D-PHY named CPHY) as its physical layer, MIPI CSI-3 uses the MIPI MPHY. This combination of MIPI CSI-3+MPHY leads to several advantages over its predecessor. We can divide the MIPI CSI-3 benefits into those than consumers can tangibly experience and those that are mainly visible to developers.
MIPI CSI3 Benefits That The Consumer Can Experience:
1. Increased Bandwidth: While the MIPI CSI-2 + CPHY has a max bandwidth of 4 Gbps, MIPI CSI-3 + MIPI MPHY has a max bandwidth of 5.8Gbps * 4 lanes = 23.2 Gbps. Therefore it can service high-resolution, high-megapixel sensors. It can facilitate high frame rates needed for teleconferencing and camcorder functionality, like MIPI CSI-2 never can. A camera capable of capturing HD or 3-D video would have two video streams. HD would need 6.6Gbps banwidth while 3-D would need 13Gbps bandwidth. Also, while here we are only talking about HD the world is moving towards UHD! Thus for the next generation video, you will have to upgrade your sensor to have MIPI CSI-3.
2. Lower Power Consumption: Given we will use most camera-laden devices on-the-go, we would need processors that can perform with lower power. This holds true from tablets/netbooks, consumer wearable devices, automotive and portable medical devices. The following features make MIPI CSI3 + MPHY much more power efficient than MIPI CSI-2+CPHY:
- Flexible data rate: Ranges from 10kbps to 5.8Gbps depending on application needs
- Lower energy per bit threshold rate promotes power efficiency
- Power management features like lower latency transition between power states: This is a advanced power management technique offered by M-PHY to improve low-power performance.
3. Lower Latency: During a video-conference session a delay in action and media response weakens the sense of interaction. To overcome this problem the networking layer (MIPI UniPro) of MIPI CSI-3 provides low latency capability.
4. Smaller Footprint: Provides higher bandwidth over fewer pins with better power per bit efficiency than MIPI CSI-2. Given it requires reduced number of pins, MIPI CSI-3 devices can be more compact
5. MPHY Lane Asymmetry: This feature can benefit camera, modem, and other applications that are highly asymmetric in traffic.
6. Lower EMI: MIPI CSI3 uses the MIPI MPHY which has lower EMI. Mobiles must produce very low EMI to minimize interference between the many radios that can be present in a device, which can include 3G and 4G/LTE mobile broadband technologies, Wi-Fi, Bluetooth, and Global Navigation Satellite Systems (GNSS), including GPS and other satellite constellations.
MIPI CSI3 Benefits To Camera Developers:
There are some more advantages that benefit camera developers directly, but not the consumer
1. Simplified Design: MIPI CSI-3 provides the ability for a device to identify its type and operational parameters and uses the single M-PHY bus instead of two buses one with D-PHY and another with the I2C. This in turn simplifies the design process.
2. Reduced Design Time Effort For Camera Applications: To reduce design-time effort and focus more on the development of Camera Application Layer rather than on the data transport issues, a standard protocol for networking layer( MIPI UniPro) and physical layer(M-PHY) is defined. This frees up time for designers to develop innovative and differentiating applications.
3. Improved Chip-to-Chip Interface Communication: MIPI UniPro and MIPI M-PHY is planned to be point-to-point and switch based architecture. It improves the chip-to-chip interface communication and routing to co-processors
4. Optical Friendly: MIPI CSI3 is optical friendly which means that mobile product designers will be able to have an option to design low complexity electro-optical signal conversion for additional assembly and reliability benefits. Optical media converter (OMC) functional layer provides the option of inserting an optical link in between two MIPI M-PHY devices for additional routing options.
There has been some delay in the adoption of MIPI CSI-3. The delay has been caused due to MIPI CSI-2 “catching up” with MIPI CSI-3 due to bandwidth enhancements. While this may suffice for the time being, at the end of the day, it is a short term patch. In the longer term, adoption is driven by technology and consumer trends, all of which favour a step change in camera technology. The future belongs to camera developers that recognize these advantages, and make the switch from MIPI CSI-2 to MIPI CSI-3. Success often comes to those who have the aptitude to see way down the road!
So do you think that MIPI CSI3 will be a game changer? Let us know in the comments below.
Authors: Laxman Sahoo, Neha Mittal, Anand Shirahatti
Image courtesy of Boians Cho Joo Young / FreeDigitalPhotos.net