Issue with access to some W5500 registers

Question

To test the reliability of the SPI communication between the microcontroller EFM8LB12 and the module W5500io, I execute several reading and writing commands on different registers of the W5500. The SPI/SCLK frequency used is 12MHz. The reading of all Common and Sockets registers gives the reset values found in the datasheet. I use always the Variable Data Length mode. For example, when I read the common registers [0x0009-0x000E], I find the correct Source Hardware Address written on the PCB of the module. After reset, when I read the socket0 Destination Hardware Address registers [0x0006-0x000B], I find the reset value written in the datasheet : 0xFFFFFFFFFFFF. This is correct. After having written [0x13-0x88] in the socket0 Source Port Register[0x0004-0x0005], I find the same value after a reading command. This is correct. But after having written the values [0x08-0xDC-0x00-0x01-0x02-0x0A] in the socket0 Destination Hardware Address registers [0x0006-0x000B], I read the values [0xFF-0xFF-0xFF-0xFF-0xFF-0xFF]. The writing does not work. It is the same issue for other registers like Socketn Destination IP Address Register which remains [0x00000000] after writing anything… I don't understand why the issue is limited to only some registers like those explained above. Thanks for an answer.

Aimee0 · Answer

Thank you for your inquiry. To help diagnose the issue, please check the following points: Are you using the latest version of WIZnet’s ioLibrary? Older versions may contain bugs related to register access. Please ensure you are using the most recent release from the WIZnet GitHub repository. Have you completed all necessary initialization steps for the WIZnet chip before accessing the common registers? Make sure your SPI communication is set to Mode 0 or Mode 3 only. W5500 supports only SPI Mode 0 and Mode 3. Using other modes may result in incorrect timing and communication failures.