Preparatory discussion

[DeeJay]

Starting to explore how to exploit a WizFi360-EVB-Pico using microPython

https://docs.wiznet.io/Product/Open-Source-Hardware/wizfi360-evb-pico

I bought one of these eval boards a few days before Raspberry Pi announced their Raspberry Pi Pico W board. A PicoW can be connected to the Internet with a few lines of microPython.

There is apparently no corresponding trivial solution easily available for the WizFi360-EVB-Pico.

This Issue is raised as a place to discuss possible options.

[DeeJay]

A WizFi360-EVB-Pico appears to be a Wiznet WizFi360-PA (PCB Antenna) module glued to the end of an RP2040-based Raspberry Pi Pico clone. Power lines and serial UART Tx/Rx data lines are routed between the module and the RP2040 via the shared PCB.

The example application source codes are written in C/C++. The documentation for the firmware on the WizFi360 module indicates that it provides an AT ('Hayes modem') interface. I don't understand enough C to determine whether the published source code provides wrappers around the AT interface or whether there is a lower-level API being exposed and exploited.

[DeeJay]

WiznetHK have published YouTube videos demonstrating how to use the AT interface on the module to associate with a wireless AP and use a TCP client or an MQTT client. But this is done using a serial connection directly from a Windows workstation using a USB-Serial adapter and some form of terminal emulation software. They demonstrate using Hercules. No doubt PuTTY would work as well.

In our case the 'workstation' is the Pico clone that is acting as host to the wireless module. Tools available for Windows are not applicable in this situation.

So the missing part of the picture is that the microPython session on the Pico clone needs to be running some sort of terminal session, perhaps equivalent to mainstream Python's serial.tools.miniterm module, acting as a 'bridge' between the REPL or executing script on one side and the serial UART on the wireless module on the other.

[DeeJay]

It seems that Twilio have a closely-related example aimed at using a Pico together with a cellular modem.

The specifics of the cellular modem instruction set will need changing, but the overall framework looks promising. A possible basis for experimentation.

The documentation for the AT command set in the upgradeable firmware on the WizFi360 module is here.

[DeeJay]

Another potentially useful parallel is that prior to the Pico W and WizFi360-EVB-Pico a common wireless implementation was to make use of an ESP8266 running AT-firmware.

This post provides a detailed example and some model code that might be a basis for adaptation.