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Original question:

INA239: Con not get SO signal from INA239

INA239: The MISO does not response

Ronan Liu
Prodigy 10 points
Part Number: INA239

Hi Experts,

I am system engineer from audio department. I built a demo board with the INA239 to monitor the PVDD voltage and current.

The same issue as this, but I don't use the CS to control(actually the CS is always connected to the Ground)

I don't know what is happened, here is my operation timing.

1, write the register 00 = 8000, reset the chip. The spi command is 0x 00 80 00.

2, waiting for 600ns(sclk) * 4096 or even more, I try to read the die id, send the spi command 0x fd 00 00.

3, But I don't find any feedback of MISO. It is always '0' output.

Could you help me to understand what was happened?

  • 0
    TI__Expert 6602 points

    Hi Ronan, 

    Do you mind supplying any information on your design as well as a scope shot of the SPI communication? This would be a good place to begin troubleshooting.

    Best,

    Mohamed 

  • 0 in reply to Mohamed Hamida
    TI__Prodigy 10 points

    Hi Mohamed,

    I think I found this issue since the POR timing is 300us. But my FPGA logic will start the SPI communication will repeat cycle by cycle. In that case, the state machine seems to be incorrect. 

    Now I will wait for 2ms delay, then start to SPI read/write, Now the SO is correct.

    BTW, could you give me a default timing sequence for this chip. I don't find it on the DS. But I think that is very important for application.

    Thanks.

    Ronan

  • 0 in reply to Ronan Liu
    TI__Expert 6602 points

    Hi Ronan, 

    You can find the default timing requirements and timing diagram on page 7 of the datasheet: 

    Please let me know if you have any further questions! 

    Best,

    Mohamed