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LMK04832EVM: Accessing the SPI-port without USBANY & TICSPRO

Part Number: LMK04832EVM
Other Parts Discussed in Thread: LMK04832


we connected the SPI-port of the LMK04832 on the LMK04832EVM with our FPGA-test-device to integrate/test our FPGA-SPI-driver.
For this we did not connect the USBANY to the SPI-header J46 but instead we connected the SPI-port by using our FPGA-test-device.

We simply tried to read out the internal register of the LMK-device, but we did not succeed --> each register was read out with 0x00
According the User-manual of the LMK04832EVM we have to supply the EVM with 4,5V --> Ok.
We did not connect 122.88MHz to CLKin*.
Question1: is the 122.88MHz on CLKin* required to run the SPI-IF?

Are there other preconditions necessary to "start" the SPI-IF?
The only pjns we are driving from our FPGA-test-device are the SPI-pins: SCK, SDIO, CS'.
The other pins are floating.
Question2: is it neccessary to drive the RESET-pin by our FPGA?

We also set the RESET-Bit in Register 0x000 and then we tried to read out the internal register via SPI, but again each register was read out with 0x00.
Question3: Do we have to consider a special programming-sequence (in addition to setting the RESET-Bit in Register 0x000)?

Thanks in advance
Best Regards
Bodo Rauhut

  • Hi Bodo,

    SPI operation does not require an input clock at CLKin. 

    After Vcc power up, SPI is default to 3-wire mode and SDIO pin is default to open drain. As such, we need a pull-up resistor at this pin in order to have it output data.

    The EVM has reserved a pull-up resistor but it is not populated. Please add back the resistor to see if you can make a readback.