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Original question:

TM4C129ENCPDT: not able to receive Data, data sent using SSI uDMA Basic mode in EK-TM4C129EXL board

TM4C1294NCPDT: How to adjust SPI timing?

Guo Yinxiu
Prodigy 170 points
Part Number: TM4C1294NCPDT
Other Parts Discussed in Thread: AWR2243

Hi,  we use TM4C1294NCPDT control AWR2243 by SPI interface.

We send data from TM4C1294NCPDT to AWR2243 based on mmwavelink, but AWR2243 has no response; then we captured SPI signal, found the sent data is right(0x56788765), but the timing is abnormal, the follow two requirments(mmWave-Radar-Interface-Control.pdf 3.2.4) are not met:

1 Host should ensure that there is a delay of at least 2 SPI clocks between CS going low and start of SPI clock

2 There should be a delay of at least 2 SPI Clocks between consecutive CS

How to adjust the two timing?

  • +1
    TI__Guru**** 190806 points

    Hi,

      The SPI module hardware does not have a means to control the delay between CS and SPICLK. You will need to use a GPIO as the CS for AWR2243. With GPIO, you can have better control of the relationship between CS and SPICLK. You simply set a GPIO pin low first and then start a SPI transfer. After the SPI transfer is complete, you then set the GPIO pin high. Many people use GPIO instead of the Fss pin for similar reason.