W7500P can go Ethernet to serial but not serial to Ethernet

Question

l have a problem with an W7500P E2S on my custom board. I can configure the W7500P with the configuration tool. I can only get data to flow one way from Ethernet to serial not back the other way. I have set my serial com port settings to no flow control. I attach my config file for your reference. I have set the WIZNET to be a TCP Server with a static IP address of 191.168.1.251 and to listen on port 50004. I can make a client TCP connection to the device and send data and it comes out on the U_TXD0 pin which I can see on the scope and also by connecting up a serial terminal on this port. But when I loop back the U_TXD0 pin to the U_RXD0 pin don’t receive anything back on the Ethernet TCP client side. I have scoped the U_RXD0 pin and again I can see the loopback data framed correctly. I have connected my laptop directly to the RJ45 socket of the W7500P with an ethernet cable to simplify the network (setting my laptop IP address to 192.168.1.253) and also so I can run Wireshark. With Wireshark I can see the TCP client sending data to the W7500P and I can also see the Ack packets coming back from the W7500P. But again I can’t see any data that I send from the W7500P back to the TCP client. The wireshark test makes me think I have my W7500P hardware correct otherwise I wouldn’t see the ACK packets from the W7500P (and I also would not be able to open a TCP socket connection, or run the Wiznet configuration tool successfully). This makes me think I am missing something fundamental on the configuration side or maybe on the hardware configuration of some misc GPIO pin on the WIznet but I can’ see what. Please see my circuit diagram attached. Can you please check my configuration and schematic files attached and advise if I have missed something. Thanks and kind regards Michael

becky · Answer

Schematic file not attached. Please attach it.

michaelsimp · Answer

Hi Also here is the contents of my config tool file - thanks for your help: LI192.168.1.251 SM255.255.255.0 GW192.168.1.1 IM0 DS8.8.8.8 CP0 TE0 SP DG0 OP1 LP50004 RH192.168.1.14 RP50004 BR12 DB1 PR0 SB0 FL0 PT0 PS0 PD00 IT0 KA1 KI7000 KE5000 RI3000 SC00 TR8 CA0 CB0 CC0 CD0

michaelsimp · Answer

Note: On my schematic the W7500P Boot pin 52 has been tied low to start the application.

becky · Answer

Have you set the AT Command command through UART? If there is a problem with the UART RX, the AT Command will not work. I hope you test this out.

michaelsimp · Answer

Hi Before I built my custom board with the W7500 I built a proof of concept using the WIZ750SR module which all worked fine. I configured it through the ethernet interface using the WIZNET Config utility and disabled the AT command entry +++. I just configured it as a TCP Server for transparent serial to ethernet communications and it just worked perfectly in both directions (E2S and S2E) I have not set any AT commands through the UART. Do you mean UART0, the main E2S UART? Are you saying I have to send an AT command to enable it to receive serial data and send it out of the TCP server socket? If so, what command must I send. I have tried two boards with W7500Ps and they behave identically in that the receive TCP data as a server and sent it out of the UART0 transmitter, but don’t send data which I put on the serial UART receiver pin out of the TCP socket. So I don’t think its a faulty or damaged W7500P (unless there was a bad batch). I must be doing something wrong but can’t think what? Thanks Michael

becky · Answer

You confirmed that Serial Tx works in S2E, and there is no problem with Ethernet as TCP Connection is established. However, You have never seen Serial RX work, so please check it out. You can confirm this by setting the AT Command. AT Command uses the same UART0 as UART in E2S.

michaelsimp · Answer

Hi Becky Thanks for your help so far. I have now successfully tested command mode on my Wiznet through the serial UART0. I start with an external TCP client connection to my Wiznet running as a TCP server. The Wiznet receives data from the TCP client and outputs it on the U_TXD0 pin but local TTL data sent to my U_RXD0 pin does not arrive at my TCP client. So I have Ethernet to serial but not serial to Ethernet. (This is the problem I am trying to solve). I send the “+++” to my Wiznet U_TXD0 pin to enter command mode. My TCP client gets disconnected and can’t reconnect. (sounds reasonable) I can send all the commands and get expected responses per the document http://wizwiki.net/wiki/doku.php/products:wiz750sr:commandmanual:start. All comms are perfect in that every command results in the correct response and monitoring the TXD and RXD pins on an oscilloscope show perfect clean serial data. When I send the “EX” command to exit command mode and then my TCP client can connect again. Then once again, my Wiznet receives data from the TCP client and outputs it on the U_TXD0 pin but I still have the problem that TTL serial data sent to my U_RXD0 pin does still not arrive at my TCP client. https://wizwiki.net/wiki/doku.php/products:wiz750sr-110:overview:en states “Optional DTR/DSR signals supported (Status pins or DTR/DSR pins selectable)”. How is DTR/DSR selected or more to the point deselected? Could this be why my Wiznet will not send TTL data to the TCP client? My circuit (above) has DSR and DTR not connected. I have tried pulling DSR both high and low but it does change things with respect to only having one way communication from Ethernet to Serial and not Serial to Ethernet. The only commands I am not happy about are the SC S0 and S1 commands: Send: SC Received: SC00 PHY link status / TCP Connection Status Send: S0 Received: S01 PHY link down Send: S1 Received: S10 TCP connection established This seems wrong to me. Using Wireshark I can see TCP connections being…

michaelsimp · Answer

Hi I really need some help with this issue please.

michaelsimp · Answer

Hi Becky I have spent days on this and checked everything before contacting you again. I don’t think the information I have given you points this as I have said: My network is very simple. Laptop plugged directly into Wiznet socket. I have tried several TCP client apps on my laptop and they all can send to the Wiznet which works E2S but not receive S2E. I have tried a second PC as the TCP client in case there is an issue with my laptop I have replaced the Wiznet with a second laptop running a TCP server and I have good comms in both directions E2S and S2E which rules out firewalls etc on my laptop TCP client I have monitored with Wireshark can can see Ack packets coming from the Wiznet when I send data from my TCP client, but nothing when I send data from the Wiznet serial port. Can you please comment on my findings of the regarding the SC S0 and S1 commands as follows: https://wizwiki.net/wiki/doku.php/products:wiz750sr-110:overview:en states “Optional DTR/DSR signals supported (Status pins or DTR/DSR pins selectable)”. How is DTR/DSR selected or more to the point deselected? Could this be why my Wiznet will not send TTL data to the TCP client? My circuit (above) has DSR and DTR not connected. I have tried pulling DSR both high and low but it does change things with respect to only having one way communication from Ethernet to Serial and not Serial to Ethernet. The only commands I am not happy about are the SC S0 and S1 commands: Send: SC Received: SC00 PHY link status / TCP Connection Status Send: S0 Received: S01 PHY link down Send: S1 Received: S10 TCP connection established This seems wrong to me. Using Wireshark I can see TCP connections being established, data flowing one way to the Wiznet and Acks coming out of the Wiznet so how can the PHY be link down? Also my RJ45 LEDs indicate it is up. And while in command mode, my TCP client connection is dropped and unable to be reestablished (which seems reasonable) so how can the Winznet report “TCP connection…

michaelsimp · Answer

Hi Becky and Wiznet. I have solved my problem but I have to say I am a little dissapointed in Wiznet support for two reasons: You keep out of date schematics for the W7500P on your web site W7500P_Ref_Schematic_V100.PDF which has a vital piece of information missing. I just found a schematic wiz750sr_v1.2.pdf for a drawing revision 1.1 is also on your website but this is named wiz750 and seeing as the chip I have is the 7500 I referenced the W7500P_Ref_Schematic_V100.PDF. You need to get this sorted and to make things worse if you follow the W7500P page to the schematci link http://wizwiki.net/wiki/doku.php?id=products:w7500p:ref_sch tells you to Go to WIZnet Github This page gives 4 versions of the schematic V100, V110, V120, V130 all of which are variants of W7500P_Ref_Schematic_V100.PDF which have the vital piece of information missing. You need to tidy this up - PLEASE TAKE DOWN ALL OUT OF DATE ERRONEOUS SCHEMATICS. The symptoms I have been reporting to Wiznet should have enabled you to solve my problem immediately. Instead I found myself being told to recheck the basics and basically I feel I was fobbed off. I reported: E2S worked but S2E did not work ie only data flowed in one direction The “AT” command “S0” returned “S01” = PHY link down, even though my RJ45 both LEDs were working and I could establish a TCP server socket had communications in both direction as monitored from Wireshark. The problem/solution is pin 23 of the W7500P must be tied to pin 14 as mentioned by a note in the V1.2 version of the schematic even though it is not obviously drawn on the circuit. The note states "_ * Caution PA_09 pin must be connected._ * This pin is PHY LINK check pin(input). and this pin checks PHY link from peer"* This is a bit of an unexpected requirement as clearly you guys could not connect my problem to this requirement so it should be much more clearly documented than it is. My board now appears to be operation to the level I can start some proper testing…

becky · Answer

Hi Michael I ’m glad you solved it well I am sorry that you are disappointed. I asked the Hardware team to review your schematic, but it took time. Before that, I wanted to give you some feedback. I am sorry that this has confused you. W7500 (P) is not a S2E dedicated CHIP. Therefore, we cannot name the schematic for WIZ750SR as W7500 schematic. Thanks for the feedback and will try to reflect it in the future. Thank you for the feedback and will reflect it in the future.