Video processors exceed automotive instant-on regulations

Article By : Vivek Nanda

The TW8844 and TW8845 instantly display rearview camera live video exceeding U.S. Federal Motor Vehicle Safety Standard (FMVSS-111) by 4x to prevent accidents when reversing.

This product announcement relates to the sad story of 2-year-old Cameron Gulbransen who was accidently and fatally knocked down by his father as he reversed his car in 2002. His father pleaded with the U.S. Congress to legislate preventative action using what was back then already readily available technology. In 2008, they finally passed a law that resulted in a Federal safety rule in 2014 requiring all new vehicles sold in the U.S. beginning in May 2018 to have rear-view cameras and the rear camera video to display less than 2s after the driver places the vehicle into reverse gear.

That's where Intersil's new product comes in. Not only is Intersil, a subsidiary of Renesas Electronics Corp. since February 2017, claiming it has the automotive industry's first full HD (1080p) LCD video processor but that the product provides the reliability needed to ensure rear-view camera systems are compliant with the U.S. Federal Motor Vehicle Safety Standard (FMVSS-111) for preventing injury or death caused by such accidents.

The TW8844 enables the migration from analog to digital camera systems and supports a variety of video interfaces and LCD panel resolutions up to full HD 1920 x 1080. The video processor with MIPI-CSI2 output and TW8845 video processor with BT.656 output exceed the requirements of the FMVSS-111 law displaying live video with graphics overlay in less than 0.5s after vehicle ignition.

In an interview with EDN Asia, Jonpaul S. Jandu, senior marketing manager at Renesas' Intersil, explained: "If you just start the car, the whole system has to boot up. And today they are running very complicated operating systems—Android, Linux, even some Windows. Depending on the processor and the OS, it could take 5s or 6s to boot up.

"That was the big challenge that a lot car companies saw. General Motors, for instance, has a workaround that I don't like. I have a GM car. When you touch the door to open it, the whole head unit wakes up. So by the time you sit down and start the car, you can see the camera in less than 2s [of starting the car]. But, if I open the door just grab my sunglasses and close it, my whole display wakes up and I hear the [boot-up] music and I worry if it's going to turn off. So, it's wasting a boot cycle and it's wasting energy.

"The TW8844 is basically a hardwired solution. We just have registers. So you set a few register settings, it's firmware and then it goes by itself. It's not relying on a heavy software stack. We can boot-up, sync to even an analog source and scale it and drive an LCD directly in less than half a second."

The TW884x series provides a rear-camera architecture to overcome the fast boot reliability issues inherent with today’s more complex centre stack systems, claims Intersil's press announcement.

Jandu explained that what car companies are worried about is that the software freezes or crashes after the driver put the car in reverse and sees the camera. Since the video frame would be frozen, the driver may assume that nothing has changed. "Technically you comply with the law but if it's not live video, it is useless," said Jandu.

The TW884x eliminates this problem by monitoring the SoC and camera output to determine if they are in a frozen or corrupted state. If the TW884x detects any issue it bypasses the SoC and instantly displays the rearview camera video.

Figure 1: System architecture. TW884x has more digital inputs to allow for either analog or digital camera. The EEPROM fast boot function enables fast boot with no MCU needed.

Key features and specs of TW8844 and TW8845:

  • Support several video inputs from analog or digital HD cameras:
  • 10-bit ADC NTSC/PAL analog video decoder supports differential pseudo differential and single ended composite video inputs (two differential or four single-ended) with built-in short-to-battery and short-to-ground diagnostics
  • Two independent digital RGB input ports up to 24-bit RGB at 160MHz (1080p) each
  • Two LVDS OpenLDI input ports (shares pins with the 2nd DRGB input) in 1-ch or 2-ch input mode with 100MHz (max) per channel in 1-ch mode or 160MHz in 2-ch mode
  • Support either one full HD input (1080p) or two HD inputs (720p)
  • Provide system flexibility to drive most LCD panels:
  • LCD path for TTL/TCON up to 24-bit DRGB 160MHz (max)
  • LVDS OpenLDI: dual channel 100MHz (max) per channel in 1-ch mode or 160MHz in 2-ch mode
  • TW8844 supports 4-lane MIPI-CSI2 output for up to 1080p with up to 1Gb/lane
  • TW8845 supports BT.656 output to the SoC with resolutions up to 720p
  • Two input measurement engines with frozen/abnormal image detection diagnostics to monitor input from the SoC and camera
  • EEPROM fast boot allows register programming without need for external microcontroller
  • Two separate H/V scalers for outputting up to 1080p (1920 x 1080) resolution allow processing of two different sources simultaneously while outputting different data to the SoC and display or they can simultaneously drive two different displays with different content
  • Automatic Contrast Adjustment (ACA) white balance and gamma correction optimizes video quality
  • Smooth input switching allows switching between various input sources without screen flicker
  • AEC-Q100 Grade-2 qualified for operation from -40°C to 105°C

The TW8844 and TW8845 can be combined with Renesas’ R-Car SoC family as well as the ISL78302 dual LDO ISL78322 dual 2A/1.7A synchronous buck regulator and ISL78228 dual 800mA synchronous buck regulator to provide power rails for the TW884x SoC and other key components on the automotive infotainment system board.

The TW8844 video processor with MIPI-CSI2 output is available in a 14mm x 20mm 156-lead LQFP package and is priced at $10 in 1,000-unit quantities. The TW8845 video processor with BT.656 output is available in a 14mm x 20mm 156-lead LQFP package and is priced at $9.50 in 1,000-unit quantities.

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