Setting Internet Pass-Thru Mode

Latest update: September 2018

In this tutorial, you will learn how to control FlashAir by using the iSDIO driver API on a RaspberryPi and set the Internet Pass-Thru Mode.

Sample environment

HW：Raspberry Pi 3 Model B ＋ microSD->SDconversion adapter
OS：Raspbian (NOOBS ver.2.4.3)
NW：Access point with Internet connection

Using the microSD conversion adapter, connect FlashAir to the microSD slot of Raspberry Pi 3 as shown above.

Sample code execution procedure

Prepare to be able to launch RaspberryPi from FlashAir as preparation.
Also, please write APPMODE=0 in the CONFIG file of the SD_WLAN folder.
See "Booting Raspberry Pi with FlashAir".
Download sample code environment from here and deploy it on RaspberryPi.
The deployment location can be anywhere.

When deployed, it will be expanded with the following configuration, so you will move from the terminal to the sample folder.

iSDIO_tutorial_sample
|-inc folder (iSDIO driver API header section)
|  |- isdio_api.h
|  |- isdio_wlan_api.h
|  |- isdioreg.h
|  └─ mmc.h
|
|-sample folder
|  |- iSDIO_tutorial_sample.c (This tutorial sample code)
|  └─ Makefile
|
└─src folder (iSDIO driver API source section)
  |- isdio_api.c
  |- isdio_wlan_api.c
  └─ isdioreg.c

Run make in the terminal. If successful, a sample folder called isdio_sample will be created.
However, since the access point names and passwords connected to the Internet differ depending on the environment, please refer to here and change.
Execute isdio_sample created in 4.
However, you need administrator privileges to use the iSDIO driver. Please execute as follows.
```
> sudo ./isdio_sample
```

I will explain the downloaded sample code (iSDIO_tutorial_sample.c).

Initialization of iSDIO driver

Initialize iSDIO card control information to use FlashAir.

iSDIO_tutorial_sample.c(Partial reference)

iSDIO_INFO_t *s_info;                                   /* iSDIO card control information pointer */
char *s_device = "/dev/mmcblk0" ;                       /* SD card device information */

/* iSDIO initialization */
s_info = iSDIO_Init(s_device);  
printf(" info=0x%p\n", s_info);
if (s_info != NULL) {
  printf("info->fno=%d\n", s_info->fno);
  system("mount /dev/mmcblk0p1 /mnt");

Line 33
Prepare a pointer to obtain the start address of iSDIO card control information.
The iSDIO card control information is acquired as the return value of iSDIO_Init and used as a handler in each command and response.
Line 34
Please change SD card device information depending on the environment because device information of FlashAir is set.
Line 53
To mount FlashAir, change it according to your environment.

Search access point

Search for access points that FlashAir can recognize.

iSDIO_tutorial_sample.c(Partial reference)

/* Acquire information on surrounding access points */
result = iSDIO_WLAN_Scan(s_info, s_seq_id ++);

if (result == E_iSDIO_OK) {
  /* Wait for completion of the iSDIO command execution process */
  timeout = 20000;          /* Scan's timeout is 20 seconds, so 20000 ms */
  cmd_success = FALSE;
  /* Wait for WLAN_Scan response */
  cmd_success = response_wait(s_info, (s_seq_id-1), iSDIO_WLAN_SCAN, timeout);

  if (cmd_success == FALSE) {
    printf("WLAN_Scan response error !!!\n");
  }
  else {

Line 55
Since iSDIO_WLAN_Scan is an asynchronous function, it is necessary to wait for a response in line 62.
Response at line 55 is the success or failure of the execution of the iSDIO_WLAN_Scan command, and the response wait at line 62 is the success or failure of the execution result of the iSDIO_WLAN_Scan command.
See here about command and response.
In addition, the sequence ID of the argument is set to a unique value each time a new command is issued. Therefore, incrementing is performed after using sequence ID.
Line 62
When response data is acquired, it decides which command execution response by command ID and sequence ID.
Therefore, we wait for response with the value -1 from the current sequence ID to set the sequence ID when iSDIO_WLAN_Scan command is executed.