Check the available values ranges
AT#GPIO=?
#GPIO: (1-6),(0-4),(0-1),(0,1)
OK
Set GPIO_3 in output, and set logical value HIGH
AT#GPIO=3,1,1
OK
Set GPIO_4 as output, value HIGH a save setting
AT#GPIO=4,1,1,1
#GPIO: 1,0
OK
Report GPIO_3 state
AT#GPIO=3,2
#GPIO: 1,1
OK
Read command
AT#GPIO?
#GPIO: 1,1 GPIO_1 is output, value is HIGH
#GPIO: 0,0
#GPIO: 1,1
#GPIO: 0,0
#GPIO: 0,1 GPIO_5 is input, value is HIGH
#GPIO: 1,0
OK