TI中文支持网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
Ben Qin：
你好，请问具体器件型号是？
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hua yan：
可以用SN74LVC245对SPI接口的SCK、MOSI、MISO增强驱动能力吗
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Ben Qin：
参考下这篇帖子：
e2echina.ti.com/…/94679
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hua yan：
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？
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Ben Qin：
我咨询资深工程师后回复您。
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Ben Qin：
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.////*****************************************************************************voidGPIOPinTypeSSI(uint32_t ui32Port, uint8_t ui8Pins){//// Check the arguments.//ASSERT(_GPIOBaseValid(ui32Port));
//// 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);}
