WIZ750SR Stuck in AT Mode

Question

I am connecting the WIZ750SR to a custom board, interfacing with a PIC24 microcontroller in TCP Server mode. When powering on the device, I am able to see it using the Configuration tool, and update its settings. I also have Debug port enabled, and can view the debug output no problem. When I power up the device, it starts in “AT Mode”. I can connect to the configuration server on port 50001, and send a “EX\r\0” command to put it back into “OPEN” mode. However, it will not respond to this command if given by the PIC microcontroller over the serial interface. I have confirmed that the UART settings are correct via oscilloscope (115200, 8 bits, No parity, 1 stop bit, No flow control) for the PIC, and the same settings are applied on the WIZ750SR. When I send the “EX\r\0” command over the Configuration TCP server (50001), I can watch the WIZ750SR change it’s configuration on the Debug port. This is also confirmed with a scan in the Configuration Tool. However, shortly after putting the device into “OPEN” mode I notice some peculiar output on the Debug port: phy id detect error!! phy id detect error!! ================================================== WIZ750SR-1xx >> WIZnet Serial to Ethernet Device >> Firmware version: 1.3.3 Stable ================================================== - Device name: WIZ750SR-1xx - Device mode: TCP_SERVER_MODE + UART IF: [RS-232/TTL] + 115200-8-N-1 / Flow control: NONE - Debug UART port: [UART2] + 115200-8-N-1 / NONE (fixed) - Serial data packing options: - Time: Disabled - Size: Disabled - Char: Disabled - Serial command mode switch code: - Enabled - [2B][2B][2B] (Hex only) - Hardware information: Status pins - Status 1: [PA_10] - PHY link - Status 2: [PA_01] - TCP connection - Hardware information: User I/O pins - UserIO A: [PC_13] - Digital / Input - UserIO B: [PC_12] - Digital / Input - UserIO C: [PC_09] - Digital / Input - UserIO D: [PC_08] - Digital / Input ================================================== # MAC: 00:08:DC:76:DF:96 # IP : 192.168.0.69 / Port: 5000 # GW : 192.168.0.1 # SN : 255.255.255.0 # DNS: 8.8.8.8 > SEG:AT Mode > SEGCP:UDP:STARTED This output will also occur randomly during power on, without changing any settings. I have a few questions: What could cause this behavior? Why am I not able to communicate with the device over UART, despite the matching serial parameters? What is the “SEGCP:UDP:STARTED” message about? I am confused about the UDP part, since the device should be operating in TCP server mode. Please advise.

Fife · Answer

After some tinkering, I found a couple things: I had accidentally made the UART connections the wrong way around (TX/RX), this partially solves my issue, as now I can send data over the UART connection. The module boots up in AT mode when it is powered on while there is a physical connection to the Ethernet port. If I disconnect the Ethernet cable when powering it on, the device goes into TCP Server mode. This behavior is still a mystery to me. Although I have partially solved the issue, I am now running into another issue that has been posted here before with no resolution. When I connect to the TCP server, there is no output from the TCP server when sending data through the UART. Furthermore, after sending a few messages, I get an error output on the debug line: “UART Rx Ring buffer Full”. Similarly to the other post, I cannot see any of the data on the debug line, despite the “Serial Debug”->Enable with data being selected. How can I resolve this issue?