WIZnet Developer Forum

WIZ850io module (W5500) not responding to any SPI read request.

I’m using an official WIZ850io module connected to an M4 MCU (via SPI).

After properly hard-resetting the w5500 via the RST pin (low@1ms, high then wait 400ms) and initializing the chip with wizchip_init(), I’m not receiving any reply to any well-formed SPI frame.

I connected a digital analyzer to check the correctness of the SPI frames being sent to the w5500, and they did result to be correct as per the w5500 datasheet. As an example, the following sampling of a ctlnetwork(CN_GET_NETINFO...) command (right after a ctlnetwork(CN_SET_NETINFO,...) command with valid data - not all 0xFFs), shows that the w5500 is not responding (all 0xFFs):

The module is properly powered @3.3V (from the same MCU power lines) and correctly connected to the MCU’s SPI. It has a loopback plug inserted in the RJ45 connector, which is correctly triggering the ‘Link’ LED on the ethernet connector.
I have 3 of these modules, and all of them behave the same (i.e. unlikely that all are failing).

What could be the issue?

Thanks for any hint.

When I had this same problem it was because my 4-pin crystal was installed 90° off. The N/C pins were connected to where the crystal pins should have been.

Just David

Thanks for the feedback… unfortunately the HW should be OK, it’s a genuine WIZ850io module bought from AVNET, and all 3 of them behave the same.

Update: I gave up and returned the modules for replacements, and the replacements now work (except one still…). Wondering about the production quality of the WIZ850io modules.

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