Automating Node and USB Settings

Automating operations such as powering on nodes or altering USB settings can be achieved by adding scripts to the /etc/init.d directory on the Baseboard Management Controller (BMC). Below, we provide a detailed guide on how to accomplish this task.

Powering On All Nodes at Startup

By default, the Turing Pi 2 doesn't power on any nodes at startup. While this can be beneficial in certain scenarios, it might not be ideal in situations like recovering from a power outage.

To alter this default behavior, a small startup script can be added. Create the file S90allnodeson.sh in the /etc/init.d directory with the following content:

#!/bin/sh

# Turn on all nodes
tpi -p on

Powering On a Specific Node at Startup

If you wish to power on a specific node at startup, utilize the script below. Create the file S91nodeon.sh in the /etc/init.d directory with the following content:

#!/bin/sh

# Wait for the API to be ready to accept requests
sleep 10

# Power on NODE 1
curl --location --request POST 'http://127.0.0.1/api/bmc?opt=set&type=power&node1=1'

Please note, we are not using tpi in this case. As of now, tpi can only power on and off all the nodes simultaneously, and not specific nodes. Instead, we are using curl to make a request to the BMC API.

Altering Node USB Settings at Startup

The USB lanes of the Mini PCI-Express for both NODE 1 and NODE 2 are multiplexed with the USB-OTG port. Therefore, when a USB setting is active for either NODE 1 or NODE 2, any USB devices connected via the Mini PCI-Express will be hidden.

On a cold boot of the Turing Pi 2, the default setting is HOST MODE for NODE 1, which will render any Mini PCI-Express modules connected to NODE 1 that use USB unavailable.

A simple startup script can ensure that HOST MODE is automatically set for NODE 3 instead. Create the file S92usb.sh in the /etc/init.d directory with the following content:

#!/bin/sh

# Change USB to HOST MODE for NODE 3
tpi -u host -n 3

Important Considerations

Order of Execution: If you create a script that changes the USB-OTG settings and powers on one or more nodes, ensure that you alter the USB settings before powering on the affected nodes. This sequence of operations is crucial for the proper functioning of your nodes.