ESP8266: makes usable channels runtime configurable

Author: Veijo Pesonen

components/wifi/esp8266-driver/ESP8266Interface.cpp

@@ -68,8 +68,11 @@ ESP8266Interface::ESP8266Interface()
     memset(_cbs, 0, sizeof(_cbs));
     memset(ap_ssid, 0, sizeof(ap_ssid));
     memset(ap_pass, 0, sizeof(ap_pass));
-    memset(_country_code, 0, sizeof(_country_code));
-    strncpy(_country_code, MBED_CONF_ESP8266_COUNTRY_CODE, sizeof(_country_code));
+
+    _ch_info.track_ap = true;
+    strncpy(_ch_info.country_code, MBED_CONF_ESP8266_COUNTRY_CODE, sizeof(_ch_info.country_code));
+    _ch_info.channel_start = MBED_CONF_ESP8266_CHANNEL_START;
+    _ch_info.channels = MBED_CONF_ESP8266_CHANNELS;
 
     _esp.sigio(this, &ESP8266Interface::event);
     _esp.set_timeout();
@@ -99,8 +102,11 @@ ESP8266Interface::ESP8266Interface(PinName tx, PinName rx, bool debug, PinName r
     memset(_cbs, 0, sizeof(_cbs));
     memset(ap_ssid, 0, sizeof(ap_ssid));
     memset(ap_pass, 0, sizeof(ap_pass));
-    memset(_country_code, 0, sizeof(_country_code));
-    strncpy(_country_code, MBED_CONF_ESP8266_COUNTRY_CODE, sizeof(_country_code));
+
+    _ch_info.track_ap = true;
+    strncpy(_ch_info.country_code, MBED_CONF_ESP8266_COUNTRY_CODE, sizeof(_ch_info.country_code));
+    _ch_info.channel_start = MBED_CONF_ESP8266_CHANNEL_START;
+    _ch_info.channels = MBED_CONF_ESP8266_CHANNELS;
 
     _esp.sigio(this, &ESP8266Interface::event);
     _esp.set_timeout();
@@ -411,7 +417,7 @@ nsapi_error_t ESP8266Interface::_init(void)
         if (!_esp.set_default_wifi_mode(ESP8266::WIFIMODE_STATION)) {
             return NSAPI_ERROR_DEVICE_ERROR;
         }
-        if (!_esp.set_country_code_policy(true, _country_code, MBED_CONF_ESP8266_CHANNEL_START, MBED_CONF_ESP8266_CHANNELS)) {
+        if (!_esp.set_country_code_policy(true, _ch_info.country_code, _ch_info.channel_start, _ch_info.channels)) {
             return NSAPI_ERROR_DEVICE_ERROR;
         }
         if (!_esp.cond_enable_tcp_passive_mode()) {
@@ -862,7 +868,7 @@ nsapi_error_t ESP8266Interface::set_blocking(bool blocking)
     return NSAPI_ERROR_OK;
 }
 
-nsapi_error_t ESP8266Interface::set_country_code(const char *country_code, int len)
+nsapi_error_t ESP8266Interface::set_country_code(bool track_ap, const char *country_code, int len, int channel_start, int channels)
 {
     for (int i = 0; i < len; i++) {
         // Validation done by firmware
@@ -872,9 +878,14 @@ nsapi_error_t ESP8266Interface::set_country_code(const char *country_code, int l
         }
     }
 
+    _ch_info.track_ap = track_ap;
+
     // Firmware takes only first three characters
-    strncpy(_country_code, country_code, sizeof(_country_code));
-    _country_code[sizeof(_country_code)-1] = '\0';
+    strncpy(_ch_info.country_code, country_code, sizeof(_ch_info.country_code));
+    _ch_info.country_code[sizeof(_ch_info.country_code)-1] = '\0';
+
+    _ch_info.channel_start = channel_start;
+    _ch_info.channels = channels;
 
     return NSAPI_ERROR_OK;
 }

components/wifi/esp8266-driver/ESP8266Interface.h

@@ -339,11 +339,15 @@ class ESP8266Interface : public NetworkStack, public WiFiInterface {
 
     /** Set country code
      *
-     *  @param country_code 2-3 character country code
-     *  @param len          Length of the country code
-     *  @return             NSAPI_ERROR_OK on success, negative error code on failure.
+     *  @param track_ap      if TRUE, use country code used by the AP ESP is connected to,
+     *                       otherwise uses country_code always
+     *  @param country_code  ISO 3166-1 coded, 2 character alphanumeric country code assumed
+     *  @param len           Length of the country code
+     *  @param channel_start The channel number to start at
+     *  @param channel       Number of channels
+     *  @return              NSAPI_ERROR_OK on success, negative error code on failure.
      */
-    nsapi_error_t set_country_code(const char *country_code, int len)
+    nsapi_error_t set_country_code(bool track_ap, const char *country_code, int len, int channel_start, int channels);
 
 private:
     // AT layer
@@ -371,7 +375,13 @@ class ESP8266Interface : public NetworkStack, public WiFiInterface {
     nsapi_security_t _ap_sec;
 
     // Country code
-    char _country_code[4]; /* ISO 3166-1 coded country code - +1 for the '\0' - assumed. Documentation doesn't tell */
+    struct _channel_info {
+        bool track_ap; // Set country code based on the AP ESP is connected to
+        char country_code[4]; // ISO 3166-1 coded, 2-3 character alphanumeric country code - +1 for the '\0' - assumed. Documentation doesn't tell.
+        int channel_start;
+        int channels;
+    };
+    struct _channel_info _ch_info;
 
     bool _if_blocking; // NetworkInterface, blocking or not
     rtos::ConditionVariable _if_connected;

components/wifi/esp8266-driver/mbed_lib.json

@@ -32,6 +32,18 @@
         "socket-bufsize": {
             "help": "Max socket data heap usage",
             "value": 8192
+        },
+        "country-code": {
+            "help": "ISO 3166-1 coded, 2 character alphanumeric country code, 'CN' by default",
+            "value": null
+        },
+        "channel-start": {
+            "help": "the channel number to start at, 1 by default",
+            "value": null
+        },
+        "channels": {
+            "help": "channel count, 13 by default",
+            "value": null
         }
     },
     "target_overrides": {