W5300 vs W5300 connection link problem

Question

Hi, i have 2 modules with W5300 chip in one rack, so they have equal power, reset timings and behavior. Each W5300 chip is used in MACRAW mode. I noticed no Link signal when they are directly connected after power on or system reset . This is a very often situation. When connecting to switch or notebook Link is alway ok. Connecting them after other devices disconnection is also always ok. I could solve this problem partly by applying a delay about 30 - 50 msec before hardware reset of w5300 chip on one of modules. Each module must be equal with the same software. How can i solve this problem? Thank you!

hjjeon0608 · Answer

Hi, I tested about your issue but all link has no problem. Plz, attach your schematic in this post.

Alex · Answer

Hi, schematic in attachment. There are Bourns TBU protectors in tx, rx cirquits between RG connector and transformer (~10 Ohm resistance). I tested with removed protectors. No changes in behavior. 1333×648 185 KB

Alex · Answer

Hi, More W5300 schematic part in attachment. I have made a few more researches. After power on and reset when cable is unplugged on oscilloscope i can see autonegotiation Fast link pulses sequence 2 ms length with period of 16 ms. On tx and on rx pin (because of auto MDI/MDIX i think). After this i connect second W5300 module with straight ethernet cable and after power on take an oscilloscope. And now i can see second Fast link pulses sequence from the second W5300 module. Two sequences are synchronously but shifted for ~1 msec so one sequense is partly covered by the other. And this shift is drifting until sequenses are not covered any more. This takes about 50 - 53 seconds. After this appears link signal. What can you say about this problem? 992×760 204 KB

jeongsk · Answer

Hi~ The circuit is no big issues. Have you ever Power-on-Reset did apply? If you do not correctly Reset, the link may fail to occur. Reset secure a lot of time. And if the link is successful late, Ethernet PHY fixed setting and testing. Another way, the Ethernet line protection circuitry is removed and tested. Thanks.