The PicoWifi

An inexpensive and easy-to-use Wifi dongle for Ataris with USB – such as the Lightning VME/ST cards. Based on the Raspberry Pi Pico W¹.

Available software: uIP tool for easy file transfer, drivers for STinG and FreeMiNT.

License terms and notice to people buying/selling hardware

PicoWifi is licensed under the GNU General Public License, Version 3 (GPLv3).

There is no official supplier of pre-programmed PicoWifi hardware, but people are free to sell such hardware, as long as they adhere to the license terms! Please see the included COPYING file for the full and legally binding license terms. But in layman's terms you have the following rights and obligations:

• You may sell hardware with pre-programmed PicoWifi firmware.
• You may modify the PicoWifi firmware and redistribute a modified version. However, such modifications must also be licensed under the same terms. Among other things you must add a notice that you modified it and you must make the modified source code available.
• As a seller you must make the license terms clear to the buyer and offer them access to the source code that corresponds to the binary you redistribute (also pre-installed on hardware). As a buyer you have the right to demand this source code.
• For binaries built from the original source, a link to this repository is sufficient. If you redistribute binaries with your modifications, you have to ensure adequate access to the source code yourself.

System requirements

• A USB interface in your Atari, e.g., the Lightning VME, Lightning ST, TwiSTEr, or NetUSBee.
• A Raspberry Pi Pico W¹, preferably obtained from an authorized reseller for about 6 USD / 7 €. Note: Select Wireless = yes from the page above and make sure you buy a Pico W (= with Wifi). A Raspberry Pi Pico (without W) cannot be used.
• No other hardware except for a suitable USB cable (Micro USB B) is needed.

Firmware installation and upgrade

• Hold down the BOOTSEL button on the Raspberry Pi Pico W while connecting it to a computer.
• The Raspberry Pi Pico W will appear as a USB mass storage device – like a USB stick.
• Copy the picowifi.uf2 firmware file onto this USB mass storage device.
• The Raspberry Pi Pico W will automatically reboot and appear as a new USB device named PicoWifi. You can verify this in the Device Manager under Windows, with the lsusb -v command under Linux, or with ioreg -p IOUSB on macOS.
• Repeat these steps whenever you want to upgrade the firmware to a newer version.

USB driver requirements on the Atari

PicoWifi makes use of the existing USB software stack for TOS and MiNT maintained by the FreeMiNT project. The USB drivers for TOS are available as a separate package, whereas the drivers for MiNT are included in the FreeMiNT snapshots.

You need at least the following drivers for PicoWifi:

• For TOS: USB.PRG, the driver for your USB adapter (e.g., BLITZ*.PRG or NETUSBEE.PRG), and the helper accessory USBTOOL.ACC.
• For MiNT: usb.km, the driver for your USB adapter (e.g., blitz*.ucd or netusbee.ucd), and eth.udd. These drivers need to be loaded by loader.prg which is also included in the FreeMiNT snapshots.

It is highly recommended to always use the latest drivers, as they might fix some important bugs. In particular, before reporting an issue with PicoWifi, please check if that issue is still present with the latest USB drivers.

Please refer to the documentation of your USB adapter for further details about the drivers and their installation and configuration.

Configuring your Wifi access credentials

Storing the credentials on the Atari

Create a text file C:\WIFICRED.CFG (or A:\WIFICRED.CFG if your Atari just has a floppy drive but no hard disk). Put into this file:

• In the first line: The SSID (name) of your Wifi network.
• In the second line: The password for your Wifi network.

Do not put anything else (comments, empty lines, …) into the file.

The PicoWifi supports WPA and WPA2 encryption.

Note: The FreeMiNT driver will also search for /etc/wificred.cfg if the files mentioned above do not exist.

Storing the credentials on the PicoWifi

Alternatively, the SSID and password can be stored in the flash memory on the PicoWifi. The Python² script wificred-store.py will ask for your Wifi credentials and store them into a file wificred.uf2 in the current directory. wificred.uf2 then needs to be written to the Raspberry Pi Pico W in the same way as the firmware: connect while holding the BOOTSEL button, then copy file.

Afterwards, WIFICRED.CFG on the Atari is no longer used, as the credentials stored on the PicoWifi take precedence.

The stored Wifi credentials are not overwritten by a firmware update. In case you want to delete them again, copy the wificred-delete.uf2 file to the Raspberry Pi Pico W.

Using PicoWifi with the uIP-Tool

A version of the uIP-Tool adapted for the PicoWifi offers a straight-forward way of exchanging files between your Atari and another computer: Get uip-usb-master.tos from here (and rename it to UIP.TOS).

On the Atari start UIP.TOS and wait until the PicoWifi has established its Wifi connection. The LED on the PicoWifi indicates a successful connection. If your network router automatically assigns IP addresses, you will then be shown the IP address under which you can connect to your Atari from another computer using a web browser (HTTP) or an FTP client.

uIP-Tool can be terminated by pressing (almost) any key; for example, Space or Esc. Don’t exit it by pressing Ctrl+C, as this can leave the USB stack in an inconsistent state.

Please refer to the uIP-Tool documentation for further explanation, in particular if you need to manually configure an IP address.

Troubleshooting:

• Using USBTOOL.ACC (from the Desktop menu: Desk – USB Utility) check that the PicoWifi is recognized as a USB device. If not, try replacing the cable, as some USB cables are only wired for charging but not for data transfer.
• If the PicoWifi is listed as a USB device but uIP-Tool still fails to connect to your Wifi network, you can get status information by pressing the F2 key within the uIP-Tool. Pay particular attention to the Wifi status line. (Note: If the password is wrong, the status might toggle between Connected and Authentication failed when you repeatedly press F2).
• By pressing the F2 key within the uIP-Tool you will also be shown the Received Signal Strength Indicator (RSSI). Values of -40 dB to -50 dB are very good. -60 dB is okay, -80 dB indicates a borderline weak connection.
• If you experience instability, e.g., sudden loss of connection or aborted transfers, even though the RSSI is good, try a different cable. Some cables cannot properly supply the peak current when the PicoWifi is transmitting³.

Note: The USB version of the uIP-Tool also supports the Asix USB-to-Ethernet adapter. You can only connect one device at a time: either the PicoWifi or the Asix adapter.

Using the PicoWifi with STinG

STinG is a popular IP network stack for TOS, providing Internet access to applications such as the FTP client Litchi or the web browser CAB. To use STinG with the PicoWifi, copy the STinG driver for the PicoWifi (USB_NET.STX) into the STING folder. Make sure to load STING.PRG after the USB drivers in the AUTO folder.

Configure STinG as indicated in its documentation. As a quick reminder, the following settings are required:

• In the STinG Port Setup CPX, select and activate the hardware – called USBether – and assign it an IP address within your home network and the appropriate subnet mask. (STinG does not support automatically getting an IP address via DHCP.)
• In the STinG Protocols CPX under Resolver assign a DNS server, most likely your home router.
• Edit the STING\ROUTE.TAB file with a text editor to define routes to your home network and a default route using your home router as a gateway.
• Furthermore, for best network performance, I recommend reducing the Delay value in the STinG Internals CPX to 10 on faster computers (e.g., Atari TT).

Again, the LED on the PicoWifi indicates a successful connection.

Note: It is recommended to update STinG’s TCP driver TCP.STX by an updated version that fixes a compatibility issue when connecting to some hosts.

Note: The USB STinG driver also supports the Asix USB-to-Ethernet adapter. You can only connect one device at a time: either the PicoWifi or the Asix adapter.

Using the PicoWifi with MiNTNet

A PicoWifi driver is available for FreeMiNT and included in the FreeMiNT snapshot builds. When updating an existing MiNT installation, copy picowifi.xif into the folder of your MiNT installation which contains the other .xif files. Don’t forget to load the MiNT USB stack – see above.

The PicoWifi network interface is called pwi0 and can be configured like any other network interface in MiNT. The following steps describe a minimal setup:

• Run ifconfig pwi0 addr x.x.x.x up, replacing x.x.x.x by the IP address you want to assign to the PicoWifi.
• Run route add default pwi0 gw y.y.y.y, replacing y.y.y.y by the IP address of the gateway, i.e., your home router.
• Both commands can be added to your mint.cnf after the line executing the USB loader.prg.
• Edit /etc/resolv.conf (or resolv.con in case of an 8+3 file system) to contain the line nameserver z.z.z.z, replacing z.z.z.z by the IP address of a DNS server, most likely your home router.

Again, the LED on the PicoWifi indicates a successful connection.

Support

The PicoWifi firmware and accompanying software are offered free of charge and – as stated in the license terms – “as is” without warranty of any kind.

Still, please feel free to report issues using GitHub’s issue tracker. However, before reporting an issue with PicoWifi, please check if that issue is still present with the latest USB drivers and the latest PicoWifi firmware. Remember that you can check the firmware version by pressing F2 in the uIP-Tool.

Building from source

In case you don’t want to use the pre-built binaries, you can build the PicoWifi firmware from the source code in this repository. The Getting started with Raspberry Pi Pico guide explains how to install the SDK and toolchain for the Raspberry Pi Pico and how to use cmake and make to build software.

The PicoWifi firmware is intended to be built with Pico SDK v.1.5.0.

Footnotes

1. Despite the name similarity, the Raspberry Pi Pico is not to be confused with the Raspberry Pi Zero, 1, 2, 3, 4. While the latter are single-board computers running Linux, the Raspberry Pi Pico is a board based on the much smaller RP2040 ARM Cortex M0+ microcontroller. The PicoWifi project does not support the Linux-based Raspberry Pi Zero, 1, 2, 3, 4, and will not be ported to them. ↩ ↩²

2. Windows users might have to install Python first. ↩

3. Even though the peak supply current (about 300 mA) is well within the allowed range for USB 1.1/2.0 devices. ↩