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MCU SPI接口与多个从设备通信

Other Parts Discussed in Thread: TM4C129DNCPDT

类似cortex m3  m4这种MCU,自带2个SPI接口,比如有40个从设备,怎么使用合适呢,有什么芯片有提高SPI的驱动能力,板内通信的话

  • 你好,请问具体器件型号是?

  • 可以用SN74LVC245对SPI接口的SCK、MOSI、MISO增强驱动能力吗

  • 比如TM4C129DNCPDT通过SPI口控制40个TMC5160芯片,怎么对SPI口进行处理呢?怎么增强SPI的驱动能力?

  • 我咨询资深工程师后回复您。

  • 你好,下面是工程师的回复:

    我认为40个外部器件在 SPI 引脚上的负载可能太大。 默认情况下、SPI 引脚配置为2mA 驱动强度。 您可以修改 TivaWare 库以改变为8mA 或12mA 等驱动强度。 您将需要使用更高的强度比如12mA,来确定它是否能够提供足够的上升/下降时间以及从器件所需的 SPI 频率。 

    通常、你可以调用 GPIOPinTypeSSI 来配置 GPIO 引脚以实现 SSI 功能。 正如您在 SSI 功能中看到的、默认情况下、2mA 用作驱动强度。 您可以将驱动强度更改为更高的值、例如12mA 或8mA、然后重建外设驱动程序库。 或者、您可以将此文件复制到工作项目中,对其进行更新然后编译它。


    //! Configures pin(s) for use by the SSI peripheral.
    //! \param ui32Port is the base address of the GPIO port.
    //! \param ui8Pins is the bit-packed representation of the pin(s).
    //! The SSI pins must be properly configured for the SSI peripheral to function
    //! correctly. This function provides a typical configuration for those
    //! pin(s); other configurations may work as well depending upon the board
    //! setup (for example, using the on-chip pull-ups).
    //! The pin(s) are specified using a bit-packed byte, where each bit that is
    //! set identifies the pin to be accessed, and where bit 0 of the byte
    //! represents GPIO port pin 0, bit 1 represents GPIO port pin 1, and so on.
    //! \note This function cannot be used to turn any pin into a SSI pin; it only
    //! configures a SSI pin for proper operation. Note that a GPIOPinConfigure()
    //! function call is also required to properly configure a pin for the SSI
    //! function.
    //! \note A subset of GPIO pins on Tiva devices, notably those used by the
    //! JTAG/SWD interface and any pin capable of acting as an NMI input, are
    //! locked against inadvertent reconfiguration. These pins must be unlocked
    //! using direct register writes to the relevant GPIO_O_LOCK and GPIO_O_CR
    //! registers before this function can be called. Please see the ``gpio_jtag''
    //! example application for the mechanism required and consult your part
    //! datasheet for information on affected pins.
    //! \return None.
    GPIOPinTypeSSI(uint32_t ui32Port, uint8_t ui8Pins)
    // Check the arguments.

    // Make the pin(s) be peripheral controlled.
    GPIODirModeSet(ui32Port, ui8Pins, GPIO_DIR_MODE_HW);

    // Set the pad(s) for standard push-pull operation.
    GPIOPadConfigSet(ui32Port, ui8Pins, GPIO_STRENGTH_2MA, GPIO_PIN_TYPE_STD);