Boot Order - Cherry Theobroma Systems PUMA SOM-RK3399-Q7 User Manual

Note: The fan is only necessary in high ambient temperatures. Under normal conditions, the RK3399-Q7 operates passively
cooled.

3.5 Boot Order

The used boot order of the RK3399-Q7 module depends on the value of the BIOS_DISABLE# signal. On the Haikou baseboard,
this signal can be set using a slider switch, with the two positions labeled Normal Boot, and BIOS Disable.
As shown in the table below, the BIOS Disable position disables both on-module storage devices:
If no bootloader is found on any storage device, the RK3399-Q7 module will go into USB loader mode where it shows up as a
USB device on the USB-OTG port.
The electrical state of the BIOS_DISABLE# signal for both slider positions is shown below:
PUMA RK3399-Q7 User Manual
© Theobroma Systems Design und Consulting GmbH
Fig. 3.3: Fan connector
Normal Boot
1 SPI NOR flash
2 eMMC storage
3 SD card
4 USB loader
Slider Position BIOS_DISABLE# signal
Floating (on-module pull-up to 1.8V)
Normal Boot
GND
BIOS Disable
BIOS Disable
SD card
USB loader
v1.7
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