spi时序

For instance, SPI communication has four transmission modes that can be freely chosen by users based on the actual situation.

This data exchange will be done after one period. Then chip selection and data transmission start again. After completing the data transfer, the controller stops transmitting SCLK, and the CS signal returns from low to high.

SPIspecification PDF

Next, let's see how to use SPI. Here we use a 6-Axis IMU module, microSD card, LCD screen and DFRobot FireBeetle ESP32-E make a recorder.

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Human vision is confined to a narrow spectrum of wavelengths and resolutions. The eye is capable of resolving various densities and pixel sizes, but in a control room (or at home) this ability is greatly affected by the distance between the viewer and the display.

It doesn't support plug-and-play(dynamic addition of nodes), and generally, there can be only one controller. Multiple devices can co-exist by chip selection, but that also means more complex connections. Besides, SPI has a high demand for wire routing because of its high transmission speed. Poor design may cause communication interrupts or data errors.

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And "serial" indicates the data transmission is implemented via serial communication, which is the same as I2C and UART. By the way, there is another method for data transmission, parallel communication. Different from the serial, data bits are simultaneously transmitted through multiple communication links in parallel communication.

spi标准

The terms HDMI, HDMI High-Definition Multimedia Interface, HDMI Trade Dress and the HDMI Logos are trademarks or registered trademarks of HDMI Licensing Administrator, Inc.

Here let's get to know these keywords one by one. "Full-duplex" means it can transmit and receive data simultaneously, just like UART. So it needs at least two communication lines.

Display size and viewing distance are two critical factors that help determine the situations in which 4K resolution would add value to an application — regardless of whether the application resides on a video wall or on the desktop. The following chart, created by Carlton Bale, compares screen size and pixel density, and clearly illustrates the ideal viewing distances for each combination.

spi通信

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Well, that's all about SPI. Feel free to add more information in the comments. Thanks for reading. If you like the article, please forward this page to your friends if you think they are helpful!

SPImode 0 1 2 3

spi协议

As the chart above illustrates, if one is viewing 4K signals on a small screen (e.g., 50 inches diagonal or less), the ideal viewing distance is approximately five feet. If one is farther away from the display, 4K imagery will effectively appear identical to that on an HD display. With 4K imagery on a larger screen (e.g., 80 to 105 inches diagonal), the ideal viewing distance increases to 12-15 feet. In contrast, the ideal viewing distance for a typical 50 inch 1080p HD display is approximately 12-15 feet, and 15-20 feet for a 105 inch 1080p display.

When the transmission mode is selected, signals can be transferred via PICO and POCI at the same time on the rising or falling clock edge, just like two trains running toward each other.

4K technology is becoming more mainstream, and 4K monitors more affordable. As a result, we are increasingly seeing 4K UHD products deployed in a wide range of market areas. However, the limitations imposed by human vision raise some interesting questions about 4K deployment. What applications can benefit most from this higher pixel density and, by extension, in which situations is the incorporation of 4K UHD processing technology most effective?

In addition, multiple SPI devices can be supported through chip selection, which requires relatively fewer hardware resources and low costs

Display devices are available in a wide range of sizes and resolutions. The smaller the screen’s diagonal size, the more densely packed its pixels will be, and the closer one would need to sit in order to discern a visible difference between lower and higher resolutions.

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Chip select pins are connected to different peripherals correspondingly. Then a peripheral can be selected by changing its CS signal from high to low. And other unselected peripherals will ignore the incoming SCLK and PICO signals, and also not send signals via POCI. After the peripheral is determined, the data transmission starts. As mentioned before, SPI uses a clock line to synchronize the transferred data bits.