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How-To WLAN

Description

The AL Pi-Tron CM4 is also available with WLAN. The recommended external antenna is the Raspberry Pi Compute Module 4 Antenna Kit which is certified for use with the Raspberry Pi Compute Module 4.

Radio Module Required

The Compute Module 4 must be a variant that includes a radio module, otherwise the use of WLAN directly with the device is not possible. Furthermore by default the CM4 radio module uses the internal PCB antenna and not the external one. A manual activation of the ext. antenna is needed. See below.

al-pi-tron-cm4-wlan

Requirements

  • Pi-Tron CM4 with WLAN
  • Compute Module 4 Antenna Kit
  • Depending on the model of the Pi-Tron CM4, the antenna kit can be included with the device.
  • If the Pi-Tron CM4 with WLAN did not come with an external antenna, obtain one separately.
  • For proper operation this antenna kit is required.
  • The antenna must be screwed onto the antenna connection of the AL Pi-Tron CM4 at the side of the housing.
  • 24 volts power supply with 2 pin power plug for the Pi-Tron CM4.
  • To login into the Pi-Tron CM4 via network, it is requires that the SSH server is running.
  • The login details are by default: username: pi and password: raspberry
  • Note: The latest version of the Raspberry Pi OS requires the user creating the initial SD card or writing the system to eMMC memory to choose a username and password or the information has to be entered during first boot of the system. The above mentioned defaults may not apply to your situation.

How-To

By default the Compute Module 4 wireless radio module uses an internal PCB antenna, which is in comparison to the ext. Antenna Kit fairly small and not intended for use if the module is encased in a housing. The Raspberry Pi OS has to be instructed manually to use the external antenna instead of the internal one.

To activate the ext. antenna an additional parameter is needed in the config.txt: For Raspberry Pi OS Buster and Bullseye use:

sudo nano /boot/config.txt

Starting with Raspberry Pi OS Bookworm and later use:

sudo nano /boot/firmware/config.txt

At the end of the file add:

dtparam=ant2

For further information regarding this parameter, see the Compute Module 4 datasheet, chapter 2.1 Wireless.

Restrictions