Android 7.1 Tablet and TV (alpha, proposal)

[Airtau]

How to use UART4? I connected the GPS module through Euler connector to UART4.

pin  9 GND --------------> GPS GND
pin 17 3.3v --------------> GPS 3.3v
pin 19 PD2 UART4_TX -> GPS uartRX
pin 21 PD3 UART4_RX -> GPS uartTX

|tulip-chiphd:/ # cat /dev/ttyGS3
there are no data

tulip-chiphd:/ # ls -l /dev |grep tty
crw------- 1 root      root         252,   0 2017-02-05 20:50 ttyGS0
crw------- 1 root      root         252,   1 2017-02-05 20:50 ttyGS1
crw------- 1 root      root         252,   2 2017-02-05 20:50 ttyGS2
crw-rw-rw- 1 root      root         252,   3 2017-02-05 20:50 ttyGS3
crw------- 1 root      root         253,   0 2017-02-05 20:50 ttyS0
crw-rw---- 1 bluetooth net_bt_stack 253,   1 2017-02-05 20:52 ttyS1


In linux  ARMBIAN 5.25 it`s working

root@pine64:~#  cat /dev/ttyS4
$GPRMC,073356.000,V,0000.000,N,00000.000,E,0.0,0.0,060617,0.0,W*6F
$GPGGA,073356.000,0000.00000,N,00000.00000,E,0,01,99.0,082.00,M,18.0,M,,*5B