Time synchronize to GPS and PPS with LattePanda Alpha

Hi, all

I want to synchronize the system time to GPS, and PPS signals using gpsd and chrony.

I have LattePanda Alpha 800s model. 

I used the GPS module (MTK3339) and it supports USB, but PPS signal is divided from USB.

If I connect the USB to Panda, I can get the GPS signal through /dev/ttyUSB0.

I already check the GPS signal with gpsmon, but I need PPS device using GPIO to synchronize the system time.

My question is

What is the pin for PPS signal for LattePanda Alpha 800s model?

I tried to add a new PPS device using pps-gpio, but when I type  “cat /sys/kernel/debug/gpio”  it says

gpiochip0: GPIOs 360-511, parent: platform/INT344B:00, INT344B:00:
gpio-401 (                    |0000:00:1e.6        ) in  lo IRQ.
 

I don't know the mapping GPIO number 360 ~ 511 and the picture of pin map of LattePanda Alpha.

How can I get the PPS device (ex. /dev/pps0) ?

I upload the pin map of  LattePanda Alpha.

Please give me advice.

Thank you.