Fan

The phyCORE-AM64x development kit provides fan connectivity via a 4-pin Hirose connector at X12 (VCC_5V0_SW rail). The fan is intended to be mounted directly to the processor heat sink for thermal management. The regulated 5V output is enabled by driving GPIO0_28 low (0), turning the fan on. When GPIO0_28 is pulled high (1), the 5V supplied to the fan connector will be turned off. This guide will demonstrate how to test your connections to the header x12. To learn more information about the phyCORE-AM64x thermal management and fan utilization, please see section 4.9 in the Hardware Manual.

Requirements

The phyCORE-AM64x development kit does not include a heat sink and fan. The below is the fan tested on the PHYTEC hardware:

Item	Description	Link
Heat Sink	(29mmx29mmx9.5mm)	Digikey link (heat sink)
Fan	DC axial fan, 30mm square x 10mm	Digikey link (fan)
Female Connector	4 pin keyed header	Digikey link (female connector)
Crimping Terminals	4x crimping jackets	Mouser link

Recommended Header Configuration

Pin	Signal	Wire Color
1	VCC_5V0_SW	Red
2	GND	Black
3	FAN_FG	Yellow
4	PWM	Blue

Connecting Your Fan

• Connect fan to the 4-pin Hirose connector located at X12.

  

Enabling the Overlay

• Power on the development kit and stop in U-boot.

• Load the device tree overlay required for exporting the GPIO signal that controls the fan and then boot the board.

  Target (U-boot)

  setenv overlays k3-am64-phyboard-electra-gpio-fan.dtbo
  boot
  

Note

For more information about overlays see chapter Configuring the Bootloader.

• Verify that the “gpio-fan” was exported properly to gpio-453.

  Target (Linux)

  cat /sys/kernel/debug/gpio
  

  Expected Output

   root@phyboard-electra-am64xx-2:~# cat /sys/kernel/debug/gpio
   gpiochip1: GPIOs 337-424, parent: platform/601000.gpio, 601000.gpio:
   gpio-355 (                    |PHY reset           ) out lo ACTIVE LOW
   gpio-356 (                    |PHY reset           ) out lo ACTIVE LOW
   gpio-379 (                    |wp                  ) out lo
   gpio-380 (                    |spi1 CS1            ) out lo ACTIVE LOW
  
   gpiochip0: GPIOs 425-511, parent: platform/600000.gpio, 600000.gpio:
   gpio-437 (                    |green:heartbeat     ) out lo
   gpio-440 (                    |red:disk            ) out lo
   gpio-441 (                    |green:disk          ) out lo
   gpio-442 (                    |home                ) in  lo
   gpio-446 (                    |menu                ) in  lo
   gpio-453 (                    |gpio-fan            ) out lo ACTIVE LOW
   gpio-457 (                    |standby             ) out lo
   gpio-460 (                    |standby             ) out lo
   gpio-488 (                    |PHY reset           ) out lo ACTIVE LOW
  

Toggling the Fan

• Turn the fan ON.

  Target (Linux)

  echo 1 > /sys/class/thermal/cooling_device0/cur_state
  

Note

Run the command above 3-4 times to have the fan stay ON consistently.

• Turn the fan OFF.

  Target (Linux)

  echo 0 > /sys/class/thermal/cooling_device0/cur_state