MODIFIED from mbed official WiflyInterface (interface for Roving Networks Wifly modules). Numerous performance and reliability improvements (see the detailed documentation). Also, tracking changes in mbed official version to retain functional parity.

Dependents:   Smart-WiFly-WebServer PUB_WiflyInterface_Demo

Fork of WiflyInterface by mbed official

Resources

Derivative from mbed Official

  • Documentation update, improved consistency, documented parameters that were inadvertently omitted.
  • Avoid c++ string handling, which causes dynamic allocation and free, side effect, fewer CPU cycles spent for same purpose.
  • Fixed socket APIs to support non-blocking mode.
  • Increase communication baud-rate to Wifly module
  • sendCommand - added retries for improved robustness.
  • setConnectionState - method to force the connection state (used by TCPSocketServer)
  • gethostbyname - added a length parameter to the size of the buffer being written
  • flushIn - a private method to flush the input buffer
  • Changed the timeout from 500 to 2500 msec for commands - measured some at 700 to 850 msec.
  • Performance improvements - reduced some unnecessary delays.
  • Added additional security options for the wi-fi connection (that are supported by the WiFly module).
  • Added setSecurity API which permits revising the security when connecting to, or selecting from, one of several access points.
  • Improved DEBUG interface (slightly more consistent printout).
  • gathers information from the Wifly module on reboot (SW version info), which permits customizing behavior based on Wifly capabilities (like the improved security).
  • Avoid potential for recursive crash (if exit fails, it calls sendcommand, which calls exit...)
  • Update to support permissible SSID and PassCode lengths.

Robustness testing

I've had some mixed behavior with the Wifly module, some of which seems to be traceable to the module itself, and some in my derivative code. The result, after running for minutes, hours, sometimes days, it hangs and I have to reset the module.

To test, I created a fairly simple test program -

  • check for Watchdog induced reset and count it.
  • initialize the Watchdog for 60 sec timeout.
  • Init the Wifly interface and connect to my network.
  • Wait 10 seconds and force mbed_reset().

If the Watchdog induces the restart, then it is pretty clear that either:

  • The communications hung with the Wifly module causing the failure.
  • The Wifly module decided to go unresponsive.

If it gets to the end, it typically takes about 4 to 6 seconds for the boot and connect, then the 10 second delay.

But I can't really pin down the root cause easily. My strongest theory is that the Wifly module has rebooted, and since I don't store the high baud rate I configure it for, it resets back to 9600.

Also, one of the objectives for my revised send( ) is to avoid the c++ string, as that can fragment memory, and it wasn't very well bounded in behavior.

Latest tests:

Warm BootsWatchdog EventsNotes
100's30An early version of my derivative WiflyInterface, including my derivative of "send( )" API. Let's call this version 0.1.
26684My derivative WiflyInterface, but with the mbed official "send( )" API. Much improved. This was over the course of about 12 hours.
24003Most recent derivative - incremental change to "send( )", but this relative number does not rule out the Wifly module itself.

I think with these numbers, +/- 1 means that the changes have had no measurable effect. Which is good, since this incremental change eliminates the c++ string handling.

Test Software

This is pieces of a test program, clipped and copied to here. What I have compiled and run for hours and hours is almost exactly what you see. This uses this simple Watchdog library.

#include "mbed.h"
#include "WiflyInterface.h"
#include "Watchdog.h"

Serial pc(USBTX, USBRX);

Watchdog wd;
extern "C" void mbed_reset();

// Pinout for SmartBoard
WiflyInterface wifly(p9, p10, p30, p29, "ssid", "pass", WPA);

int main() {
    pc.baud(460800);                         // I like a snappy terminal
    
    wd.Configure(60.0);                     // Set time limit for the test to 1 minute
    LPC_RTC->GPREG0++;                      // Count boots here
    if (wd.WatchdogCausedReset()) {
        LPC_RTC->GPREG1++;                  // Count Watchdog events here
        pc.printf("\r\n\r\nWatchdog event.\r\n");
    }
    pc.printf("\r\nWifly Test: %d boots, %d watchdogs. %s %s\r\n", LPC_RTC->GPREG0, LPC_RTC->GPREG1, __DATE__, __TIME__);
    
    wifly.init(); // use DHCP
    pc.printf("Connect...  ");
    while (!wifly.connect());               // join the network
    pc.printf("Address is %s.  ", wifly.getIPAddress());
    pc.printf("Disconnect...  ");
    wifly.disconnect();
    pc.printf("OK. Reset in 10 sec...\r\n");
    wait(10);
    if (pc.readable()) {
        if (pc.getc() == 'r') {             // secret 'r'eset of the counters
            LPC_RTC->GPREG0 = 0;
            LPC_RTC->GPREG1 = 0;
            pc.printf("counters reset\r\n");
        }
    }
    mbed_reset();                           // reset here indicates successful communication
}

Wifly/Wifly.h

Committer:
WiredHome
Date:
2013-07-22
Revision:
26:78a1a09afdc9
Parent:
25:a740eb74a86a
Child:
29:49876a8c445b

File content as of revision 26:78a1a09afdc9:

/* Copyright (C) 2012 mbed.org, MIT License
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
 * and associated documentation files (the "Software"), to deal in the Software without restriction,
 * including without limitation the rights to use, copy, modify, merge, publish, distribute,
 * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all copies or
 * substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
 * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * @section DESCRIPTION
 *
 * Wifly RN131-C, wifi module
 *
 * Datasheet:
 *
 * http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Wireless/WiFi/WiFly-RN-UM.pdf
 */

#ifndef WIFLY_H
#define WIFLY_H

#include "mbed.h"
#include "CBuffer.h"

#define DEFAULT_WAIT_RESP_TIMEOUT 1000

enum Security {
    NONE = 0,
    WEP_128 = 1,
    WPA = 3
};

enum Protocol {
    UDP = (1 << 0),
    TCP = (1 << 1)
};

/** the Wifly object
*
* This object controls the Wifly module.
*/
class Wifly
{

public:
    /**
    * Constructor
    *
    * @param tx mbed pin to use for tx line of Serial interface
    * @param rx mbed pin to use for rx line of Serial interface
    * @param reset reset pin of the wifi module ()
    * @param tcp_status connection status pin of the wifi module (GPIO 6)
    * @param ssid ssid of the network
    * @param phrase WEP or WPA key
    * @param sec Security type (NONE, WEP_128 or WPA)
    */
    Wifly(PinName tx, PinName rx, PinName reset, PinName tcp_status, const char * ssid, const char * phrase, Security sec);

    /**
    * Destructor to clean up
    */
    ~Wifly();
    
    /**
    * Connect the wifi module to the ssid contained in the constructor.
    *
    * @return true if connected, false otherwise
    */
    bool join();

    /**
    * Disconnect the wifly module from the access point
    *
    * @ returns true if successful
    */
    bool disconnect();

    /**
    * Open a tcp connection with the specified host on the specified port
    *
    * @param host host (can be either an ip address or a name. If a name is provided, a dns request will be established)
    * @param port port
    * @ returns true if successful
    */
    bool connect(const char * host, int port);


    /**
    * Set the protocol (UDP or TCP)
    *
    * @param p protocol
    * @ returns true if successful
    */
    bool setProtocol(Protocol p);

    /**
    * Reset the wifi module
    */
    void reset();
    
    /**
    * Reboot the wifi module
    */
    bool reboot();

    /**
    * Check if characters are available
    *
    * @return number of available characters
    */
    int readable();

    /**
    * Check if characters are available
    *
    * @return number of available characters
    */
    int writeable();

    /**
    * Check if a tcp link is active
    *
    * @returns true if successful
    */
    bool is_connected();

    /**
    * Read a character
    *
    * @return the character read
    */
    char getc();

    /**
    * Flush the buffer
    */
    void flush();

    /**
    * Write a character
    *
    * @param the character which will be written
    */
    int putc(char c);


    /**
    * To enter in command mode (we can configure the module)
    *
    * @return true if successful, false otherwise
    */
    bool cmdMode();

    /**
    * To exit the command mode
    *
    * @return true if successful, false otherwise
    */
    bool exit();

    /**
    * Close a tcp connection
    *
    * @ returns true if successful
    */
    bool close();

    /**
    * Send a string to the wifi module by serial port. This function desactivates the user interrupt handler when a character is received to analyze the response from the wifi module.
    * Useful to send a command to the module and wait a response.
    *
    *
    * @param str string to be sent
    * @param len string length
    * @param ACK string which must be acknowledge by the wifi module. If ACK == NULL, no string has to be acknoledged. (default: "NO")
    * @param res this field will contain the response from the wifi module, result of a command sent. This field is available only if ACK = "NO" AND res != NULL (default: NULL)
    * @param timeout is the time in msec to wait for the acknowledge
    *
    * @return true if ACK has been found in the response from the wifi module. False otherwise or if there is no response in 5s.
    */
    int send(const char * str, int len, const char * ACK = NULL, char * res = NULL, int timeout = DEFAULT_WAIT_RESP_TIMEOUT);

    /**
    * Send a command to the wify module. Check if the module is in command mode. If not enter in command mode
    *
    * @param str string to be sent
    * @param ACK string which must be acknowledge by the wifi module. If ACK == NULL, no string has to be acknoledged. (default: "NO")
    * @param res this field will contain the response from the wifi module, result of a command sent. This field is available only if ACK = "NO" AND res != NULL (default: NULL)
    * @param timeout is the time in msec to wait for the acknowledge
    *
    * @returns true if successful
    */
    bool sendCommand(const char * cmd, const char * ack = NULL, char * res = NULL, int timeout = DEFAULT_WAIT_RESP_TIMEOUT);
    
    /**
    * Return true if the module is using dhcp
    *
    * @returns true if the module is using dhcp
    */
    bool isDHCP() {
        return state.dhcp;
    }

    /**
    * gets the host ip address
    *
    * @param host is a pointer to the host string to look up
    * @param ip contains the host IP in a string after the lookup.
    * @param sizeof_ip is the size of the buffer pointed to by ip
    * @returns true if successful
    */
    bool gethostbyname(const char * host, char * ip);

    /**
    * Set the baud rate between the ARM and the WiFly.
    *
    * This will set the WiFly module baud rate first and then
    * set the ARM interface to match it. If it cannot get the proper 
    * acknowledge response, it will go on a hunt through the range 
    * of standard baud rates.
    *
    * @note Baud rate must be one of 2400, 4800, 9600, 19200, 38400, 57600,
    *       115200, 230400, 460800, or 921600. (See Wifly manual 2.3.64)
    * @note Baud rate of 230400 has been seen to be marginal w/o flow control.
    * @note Setting a baud rate to a 460800 or above may be unrecoverable
    *       without resetting the Wifly module.
    *
    * @param baudrate is the desired baudrate.
    *
    * @returns true if it succeeded, which means that communications can continue, 
    * @returns false if it failed to establish a communication link.
    */
    bool baud(int baudrate);


    /**
    * Sets the connection state. 
    *
    * Typically used by external apps that detect an incoming connection.
    *
    * @param state sets the connection state to true or false
    */
    void setConnectionState(bool state);


    /**
    * Get the version information from the Wifly module.
    *
    * @returns the version information as a string, or NULL
    */
    char * getWiflyVersionString();
    
    
    /**
    * Get the software version from the Wifly module.
    *
    * This extracts the basic version number (e.g. 2.38, 4.00)
    * as a float.
    *
    * @returns the software version number as a float.
    */
    float getWiflyVersion();


    /**
    * determine if the module is in command mode
    *
    * @return true if in command mode, false otherwise
    */
    bool isCmdMode() {
        return state.cmd_mode;
    }


    static Wifly * getInstance() {
        return inst;
    };

protected:
    Serial wifi;
    DigitalOut reset_pin;
    DigitalIn tcp_status;
    int baudrate;
    char * phrase;
    char * ssid;
    char * wiflyVersionString;
    float swVersion;
    const char * ip;
    const char * netmask;
    const char * gateway;
    CircBuffer<char> buf_wifly;

    static Wifly * inst;

    void attach_rx(bool null);
    void handler_rx(void);
    void flushIn(int timeout_ms = 0);

    typedef struct STATE {
        bool associated;
        bool tcp;
        bool dhcp;
        Security sec;
        Protocol proto;
        bool cmd_mode;
    } State;

    State state;
    char * getStringSecurity();
    
    /**
    * Estimates the time needed for the Wifly module to respond
    * to some of the simple commands.
    *
    * This should only be used for simple commands, where the module should
    * be able to respond almost immediately.
    *
    * @param stringLen of the command to be sent, in characters.
    *
    * @returns integer number of milliseconds (always rounded up a little)
    */
    int timeToRespond(int stringLen);

    /**
    * Allocate space for the parameter (ssid or passphrase)
    * and then fix it (change ' ' to '$').
    *
    * @param dst is a reference to the private member pointer.
    * @src is a pointer to a passed in string.
    */
    void FixPhrase(char ** dst, const char * src);

    /**
    * Gather the Wifly module version information for later queries
    */
    void GatherLogonInfo();

};

#endif