SPI-Based HUD Backlight Control via Command Bundling
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Solution Overview
Problem
Existing SPI-based Head-Up Display (HUD) backlight control methods face challenges in ensuring smooth backlight adjustments due to frequent transmission requirements, leading to display flicker, as the SPI bus is often occupied, making it difficult to transmit backlight setting commands at the necessary 60 Hz frequency.
Innovation Solution
The method involves using the video source signal frequency to calculate and bundle multiple backlight values into a single SPI command, allowing the LED controller to apply these values sequentially with frame synchronization signals, reducing the frequency of command transmission and spreading it out evenly, thereby reducing SPI bus load and improving smoothness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If backlight setting commands are transmitted frequently at 60 Hz to ensure smooth backlight adjustments, then the smoothness of backlight variation is improved, but the SPI bus is frequently occupied causing transmission delays and display flicker
Solution Approach 1:
The patent combines multiple backlight values (e.g., 3-6 values) into a single SPI command transmission. Instead of transmitting one backlight value per frame synchronization signal, the system bundles multiple values together and transmits them in one SPI command, reducing SPI bus occupation frequency while ensuring all necessary backlight values are delivered
Solution Approach 2:
The motor vehicle controller pre-calculates multiple backlight values in advance and bundles them into a single command before transmission. This preliminary preparation allows the LED controller to sequentially apply multiple backlight values after receiving one SPI command, eliminating the need for frequent SPI transmissions
2Ease of operation
If backlight values are transmitted one at a time via SPI bus, then the LED controller can apply them sequentially with frame synchronization, but the frequent transmission requirements cause SPI bus occupation and transmission delays
Solution Approach 1:
Multiple backlight values are merged into a single SPI command structure. The command contains an array of backlight values that the LED controller will apply sequentially, reducing the number of SPI transactions from 60 per second to approximately 10-20 per second depending on the bundle size
Solution Approach 2:
The backlight control is segmented into bundles of multiple values. Each SPI command carries a segment of backlight values (e.g., 3-6 values) that correspond to multiple frame synchronization signals, allowing the LED controller to distribute application across multiple frames without requiring frequent re-transmission
Data Source
AI summary
An SPI-based HUD backlight control method places multiple backlight values obtained by calculation into a backlight setting command and transmits the same to an LED controller via an SPI bus. After obtaining the backlight setting command, the LED controller sequentially applies one backlight value in the backlight setting command each time a frame synchronization signal is obtained. The method reduces the SPI bus load, so that the smoothness of backlight variation is increased, thereby ameliorating display flicker.