--- title: "Schematic review - W5500 not working" url: "https://maker.wiznet.io/forum/14971" markdown_url: "https://maker.wiznet.io/forum/14971/md" type: "Forum topic" category: "Ethernet Chips" author: "Matt" created: "2023-07-17T13:40:15+09:00" last_activity: "2023-08-11T06:37:49+09:00" language: "en" views: 767 replies: 26 source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)" --- # Schematic review - W5500 not working ## Question Asked by Matt on 2023-07-17 in Ethernet Chips. Hi, I have a W5500 on my PCB but it doesn’t appear to be working (I have tested code on a different W5500 board before). I used the reference schematic from here - Here is my PCB’s schematic: [![image](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/2/249bbe90809e9a253caa4d2269a3a5fa7bdf0c78.jpeg) image1920×568 140 KB](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/2/249bbe90809e9a253caa4d2269a3a5fa7bdf0c78.jpeg) Is there anything I have missed because it looks exactly the same to me? The only thing I can think of it that the EVB has the reserved pins tied to GND through a resistor even though the reference schematic hasn’t? Thanks in advance! ## Replies ### Reply 1 by Eugeny, 2023-07-17 How it does not work, and why 82 Ohm resistors? Edit: not sure what external transformer circuit has 82 Ohm resistors instead of 49.9 Ohm. ### Reply 2 by Matt, 2023-07-17 (in reply to reply 1) I am just probing the SPI lines now so will update shortly. There is not output from the device on code that has worked on previous PCB’s so will trace through where it stops now. As for the resistance I used the Wiznet reference design which uses 82ohm: Is this schematic wrong? Thanks! ### Reply 3 by Eugeny, 2023-07-17 ![](https://avatars.discourse-cdn.com/v4/letter/m/a6a055/48.png) Matt: > Is this schematic wrong? Thanks! This is a good question, but this must not be related to issues with SPI, if there’re any. Does it turn link LED on when you plug live cable in? OMG, your design does not have it! ![:cry:](https://emoji.discourse-cdn.com/twitter/cry.png?v=12) ### Reply 4 by Matt, 2023-07-17 Yeah, unfortunately I did just take the reference schematic as blind faith and if it wasn’t on there it isn’t included in mine. Is there a newer than 2015 reference schematic that does have the correct layout? Thank you! ### Reply 5 by Eugeny, 2023-07-17 As long as it is on the official website we can not deem it as incorrect ![:slight_smile:](https://emoji.discourse-cdn.com/twitter/slight_smile.png?v=12) but looks strange, and probably not a reason for thing not to work. You must identify what exactly does not work and keep working towards the root cause. For now SPI communication for digital part and link LED for analog part. ### Reply 6 by Matt, 2023-07-17 Unfortunately some other testing has blown my micro so I need to wait for a repllacement or a new revision to test it properly. Does this schematic look better? [![image](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/b/b29d8515d7ead1b99b9f2f324d30ec6b24dabfcc.jpeg) image1920×697 170 KB](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/b/b29d8515d7ead1b99b9f2f324d30ec6b24dabfcc.jpeg) Thanks for the help! ### Reply 7 by Eugeny, 2023-07-17 Do not make changes until we identify what exactly is wrong with the device to see the direction to dig into. Hope you’ll fix it quickly and issue is not that bad. ### Reply 8 by Matt, 2023-07-17 Sure, just the schematic for now. I won’t send it to get made untill I can prove it out. My thinking was that all of the changes were pull downs/ups instead of floating so I can just DNP if needed. Also added the LED’s and changed the resistors to 49.9ohms to match every other schematic I have seen. I am sending the board off tomorrow to get a new uC to get testing with this. It’s a BGA so need it done properly and X-rated. Will report back what I find ### Reply 9 by Alan, 2023-07-17 ![image](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/7/7dbbafa10bea5a91066b0506b0523d0c54ebaafc.jpeg) Hello. I ask because I can’t see the whole circuit. Is the MCU controlling the RST? I don’t think that’s the case with the drawings you showed me. ### Reply 10 by Matt, 2023-07-17 Hi, nope I tied it to 3.3V to always be activated. Should I keep this 10k but put it to the micro aswell to pull low in startup? ### Reply 11 by Alan, 2023-07-17 Yes, the MCU must control the RST. All examples contain that part. ### Reply 12 by Eugeny, 2023-07-18 Agree with Alan, if you make new board design MCU to be able driving reset pin to perform hardware reset after power up. At worst you must have at least some capacitor-based reset circuit, but it is not the best practice. ### Reply 13 by Matt, 2023-07-18 Thanks both. I have added the reset signal from the MCU. The only thing I am not 100% on now is post transformer but hopefully as that is the same as the reference design then that bit is ok! Just need to add a voltage level translator as my MCU outputs 5V. I now have this: [![image](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/6/649803370aa210b9f2cef985aac26c617f83793a.jpeg) image1920×687 171 KB](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/6/649803370aa210b9f2cef985aac26c617f83793a.jpeg) ### Reply 14 by Eugeny, 2023-07-18 ![](https://avatars.discourse-cdn.com/v4/letter/m/a6a055/48.png) Matt: > Just need to add a voltage level translator as my MCU outputs 5V. This is another point of careful consideration. While datasheet says pins are 5V-tolerant, my experience (with W5100) showed incorrect behavior when driving with 5V signals - and I dropped 5V design completely, using 3.3V MCU (actually FPGA). I do not say it will not work, I show you a possible risk I have removed in my pervious designs. ### Reply 15 by Matt, 2023-07-18 Yeah that is a good point. I have just thrown in a voltage divider for the 3.3V reset pin but don’t want to do that for SPI. Should I drop those down to 3.3V SPI as well? I can’t change MCU unfortunately. ### Reply 16 by Eugeny, 2023-07-18 The level translation (from 5V to 3V) could be done using simple series resistor or divider as you seem have done already - its nominal is calculated by the desired current of the protection diodes at both sides and desired input voltage. You are lucky all the SPI lines are unidirectional, so you do not need bidirectional translators. What you can do right now is preserve seats for resistors, solder 0R nominals, but in case of communication problems play with other nominals. ### Reply 17 by Alan, 2023-07-18 ![image](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/a/a1bd4fe50af82a6c24d8466e78f66260209d6d6f.png) I answered your inquiry through Channel Talk. ### Reply 18 by Matt, 2023-07-19 (in reply to reply 17) Great, thank you! I have no changed all 5V signals I think! Here is my newest version with voltage translators and a voltage divider for reset pin: [![image](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/1/1a2d0582063b9960e041208f3f618e1d1265aa62.jpeg) image1920×795 179 KB](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/1/1a2d0582063b9960e041208f3f618e1d1265aa62.jpeg) [![image](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/7/7a55c464a4966ba1a967cf16b19f9ec1f4de2420.png) image2627×1277 292 KB](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/7/7a55c464a4966ba1a967cf16b19f9ec1f4de2420.png) Also, do I need any kind of ESD protection? this is leaving the board as 2x twisted pairs and not through a RJ45. I hope this now looks good to go! Thaks all for the help! ### Reply 19 by Alan, 2023-07-19 Oh… I don’t think it should be organized like this. I don’t think RST will work normally… Combined with pull-up resistance, there can be a lot of problems… For example, when the voltage is applied from the Pull-up power source, the power is divided, so it’s only about 1.98V. There could be a lot of problems besides this. Not recommended. (There is also a risk of damage to the parts due to reverse voltage.) ### Reply 20 by Alan, 2023-07-19 I think it would be better if you use a buffer that can distinguish power or use TR to down the level! ### Reply 21 by Matt, 2023-07-20 (in reply to reply 20) Understood. Any thoughts on the ESD question? I have changed it to use a buffer instead: [![image](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/c/cbcef838feef85a367490fa5ac540dce9af457a0.jpeg) image1920×787 180 KB](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/c/cbcef838feef85a367490fa5ac540dce9af457a0.jpeg) [![image](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/d/dd4f5a8efa1b147f7d2b75ae0794f90f5028e961.png) image1440×1207 88.5 KB](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/d/dd4f5a8efa1b147f7d2b75ae0794f90f5028e961.png) Thanks for the pointers! ### Reply 22 by Alan, 2023-07-20 The W5500 is particularly sensitive to ESD. You have to pay a lot of attention to Artwork. If you send Gerber, I can check it for you. ### Reply 23 by zzwwss, 2023-08-08 Hi Matt Is your circuit board running normally now? I used TXB0108 bidirectional level conversion chip. The debugging is not smooth at present. I want to ask if you have successfully debugged it. ### Reply 24 by Alan, 2023-08-11 (in reply to reply 23) Hello. Welcome. Could you share the circuit? ### Reply 25 by zzwwss, 2023-08-11 [![image](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/9/91ab39921c8d8f633728efe25c967ef552804937.png) image1415×926 162 KB](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/9/91ab39921c8d8f633728efe25c967ef552804937.png) This is my circuit diagram, which is currently undergoing debugging. Could you please help to see if there are any other issues? The previous issue was that the LINKLED was always high and not lit. Previously, SPI communication was normal, but LINKLED remained at a high level. After a long investigation, it was re welded and the welding temperature was lowered to below 300. Now, by plugging in the internet cable, LINKLED can light up. I found the solution from the current website. Thank you all. ### Reply 26 by Alan, 2023-08-11 I’m glad the problem is solved. Thank you. --- Source: https://maker.wiznet.io/forum/14971