Hi,
Do you have a logic analyzer to better analyze what is happening on the SPI bus? The signals on the picture you shared are not very clear and difficult to analyze.
I would recommend you to verify the SPI configuration and ensure the SPI settings match the PT2001 requirements, including the clock polarity, clock phase and bit order (MSB/LSB).
Also verify that the PT2001 is properly powered and that all SPI lines (MOSI, MISO, SCK, CS) are connected without issues.
Ensure the data format, command codes and message framing adhere to the PT2001 protocol. If incorrect or incomplete commands are sent, the PT2001 may not respond as expected.
For details, please refer to the PT2001 full datasheet, section 13.2 - Serial Peripheral interface.
BRs, Tomas