why imx8qxp spi chip select have overturn after 8bit transfer?

cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 

why imx8qxp spi chip select have overturn after 8bit transfer?

674 Views
caoyk
Contributor I

Now wo use lpspi0 to  connect spi dev.

dts :

&lpspi0 {
#address-cells = <1>;
#size-cells = <0>;
fsl,spi-num-chipselects = <1>;
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_lpspi0>;

status = "okay";

    fm1388_spi@0 {
    compatible = "fm1388_spi";
    reg = <0>;
    spi-max-frequency = <2000000>;
    //spi-cpha;
    //spi-cpol;
    //poll_mode = <0>;
    //type = <0>;
    //enable_dma = <1>;
    };

};

 

Then lpspi0 is work fine but spi dev have no return data.

After it we use  Logic analyzer to capture spi waveform. 

Result is in Attachment.

We can see spi chip select have overturn after 8bit transfer. Maybe it cause error.

How to change chip select be high after all date  transfered, looking forward to a reply .

0 Kudos
Reply
1 Reply

427 Views
VijayAnnamalaisamy
Contributor I

Hi all,

I am also facing the same issue with iMX8 QXP. Using LPSPI0 with SPIDEV. Observing that Chip select signal comes back to HIGH after 8 bit transfer. Because of this, the response from the SPI slave was not received.

Please let me know if there is a solution to this problem.

Thanks in advance,

Vijay

0 Kudos
Reply