Hi tomalex,
The problem is solved when I updated firmware to FX30 R13.1.2.004,
https://source.sierrawireless.com/resources/airlink/software_downloads/fx30-firmware/fx30-firmware/
Below IoT expansion slot maping:
FX30 IoT connector Interface -> FX30 Resource
GPIO1 -> GPIO 42
GPIO2 -> GPIO 33
GPIO3 -> GPIO 13
GPIO4 -> GPIO 8
IOT_DETECT -> GPIO 25
USB Hub on HSIC WP interface, mounted on ttyUSB0
SDIO -> SDIO
UART -> UART2
SPI -> SPI1
ADC -> ADC0
PCM -> PCM
I2C -> I2C1
I made changes in port setting to:
void serial_SetPortSettings()
{
tcgetattr(tty_fd,&oldtio); /* save current port settings */
bzero(&newtio, sizeof(newtio));
newtio.c_cflag = B19200 | CRTSCTS | CS8 | CLOCAL | CREAD;
newtio.c_iflag = IGNPAR;
newtio.c_oflag = 0;
newtio.c_lflag = 0;
newtio.c_cc[VTIME] = 0;
newtio.c_cc[VMIN] = 1;
tcflush(tty_fd, TCIFLUSH);
tcsetattr(tty_fd,TCSANOW,&newtio);
}