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CC2640R2F SPI 最大速率

user1241768
Prodigy 30 points
Other Parts Discussed in Thread: CC2640R2F

你好：

最近在使用CC2640R2F 时候 在SPI总线上挂载两个SPI设备，当把SPI速率设置为12MHZ  时候，一切正常，但是如果把SPI速率设置为24MHZ 时候，常温下没有问题，但是温度上升到50 多摄氏度时候，SPI通讯就有问题。  

在TI的提供的datasheet 中看到上面提到SSI 最大时钟为 系统时钟的8分频（在MASTER TX&RX 模式下）即 6MHz

但是在另外一份文档 “CC13x0, CC26x0 SimpleLink™ Wireless MCUTechnical Reference Manual “” 中第1486 页提到 “For master mode, the core clock (PERDMACLK) must be at least two times faster than SSIn_CLK.  这样看来系统时钟只需要2倍SSI CLK 时钟就可以了  也就是说SPI时钟可以到 48/2 =24MHz 。


那么请问 ：

1：CC2640R2F  SPI Master 模式最大时钟可以到多少

2：两份文档为何有差异

谢谢

  • 0
    TI__Guru**** 188340 points
    TRM 文档里写了：The SSI includes a programmable bit rate clock divider and prescaler to generate the serial output clock. The bit rates are supported to 2 MHz and higher, with maximum bit rate is determined by peripheral devices.

    在SPICC26XXDMA.h定义如下：

    ## Data Frames #
    *
    * SPI data frames can be any size from 4-bits to 16-bits. If the dataSize in
    * ::SPI_Params is greater that 8-bits, then the *** driver
    * implementation will assume that the ::SPI_Transaction txBuf and rxBuf
    * point to an array of 16-bit uint16_t elements.
    *
    * dataSize | buffer element size |
    * -------- | ------------------- |
    * 4-8 bits | uint8_t |
    * 9-16 bits | uint16_t |
    *
    **********************************************************************************************************
    * ## Bit Rate ##
    * When the SPI is configured as SPI slave, the maximum bit rate is 4MHz.
    *
    * When the SPI is configured as SPI master, the maximum bit rate is 12MHz.
    **************************************************************************************************************