XS156 Theory of Operation

4 min

This section describes how specific components operate on the XS156.

On-Board LEDs

The four on-board LEDs have the following indicators:

LED	Indication
Green power (Pwr)	Displays when the board is powered up and not in reset mode. Flashes during the firmware update process.
Green file-system activity (Bsy)	Flashes any time there is file-system activity (on any storage device)
Blue WiFi (WiFi icon)	Flashes when the board is being updated
Red status (Err)	Flashes a certain number of times to indicate which error is occurring. The flash codes are described below.
	2: Unspecified error
	3: Network recovery script is preparing to run on a device configured for network recovery.
	4: No upgrade file found
	5: Failed to load kernel module
	6: Board is not capable of running the current firmware version
	7: A piece of on-board hardware is not working correctly.
	8: Problem related to the storage device (either the USB drive or microSD card)
	9: Problem related to the registry/NAND
	10: The autorun script encountered a load/run error.
	11: WiFi-related error
	12: Unable to find a bootable image

On-Board Switch / SVC Button

The on-board switch is connected to the GPIO02, which is pulled low when the service (SVC) button is pressed. Conversely, a pull-up on the button normally sets the GPIO02 to be pulled high.

Reset Switch / GPIO Button

The on-board switch is connected to the reset circuit. Pulling low on the Reset button for less than 2 seconds will initiate an orderly system reset under software control at the rising edge of the signal. If the Reset button is pulled low for more than 6 seconds, an immediate hard reset is performed.

SDIO Slot

The XS156 provides one SD card interface capable of UHS-1 operation at up to DDR50 transfer rates. A +3.3V power supply is provided for the card. This power supply can be switched on and off by the firmware, allowing it to power-cycle the SD card.

Wireless Module

The XS156 has an M.2 E Key for WiFi/Bluetooth modules.