wifi-sta-setup

Task

Bring an ESP-IDF project's WiFi STA setup into line with the monorepo canonical pattern, or audit it without modifying anything.

Invocation:

• audit <project-path> — read-only drift report against canonical.
• apply <project-path> — migrate source + sdkconfig to canonical.

<project-path> is relative to repo root, typically packages/<domain>/<project-name>.

The canonical source of truth is packages/robocar/unified/main/wifi_manager.c (identical to packages/robocar/camera/main/wifi_manager.c). That project runs reliably on XIAO ESP32-S3 Sense in the same environment as every other WiFi project in this monorepo, so its configuration is the reference.

Canonical STA init code

Drop into main/wifi_manager.{c,h} for new projects, or inline into main.c for small projects where a separate module isn't justified. The function boundary doesn't matter — these settings do:

// ---- event handler (reason-code logging is the key bit) ----
static void event_handler(void *arg, esp_event_base_t event_base, int32_t event_id,
                          void *event_data)
{
    if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_START) {
        esp_wifi_connect();
    } else if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_DISCONNECTED) {
        wifi_event_sta_disconnected_t *disconnected = (wifi_event_sta_disconnected_t *)event_data;
        ESP_LOGW(TAG, "WiFi disconnected. Reason: %d (%s)", disconnected->reason,
                 disconnected->reason == WIFI_REASON_NO_AP_FOUND         ? "AP not found"
                 : disconnected->reason == WIFI_REASON_AUTH_FAIL         ? "Auth failed"
                 : disconnected->reason == WIFI_REASON_ASSOC_FAIL        ? "Assoc failed"
                 : disconnected->reason == WIFI_REASON_HANDSHAKE_TIMEOUT ? "Handshake timeout"
                                                                         : "Other");
        if (s_retry_num < WIFI_MAXIMUM_RETRY) {
            esp_wifi_connect();
            s_retry_num++;
            ESP_LOGI(TAG, "Retry %d/%d to connect to the AP", s_retry_num, WIFI_MAXIMUM_RETRY);
        } else {
            xEventGroupSetBits(s_wifi_event_group, WIFI_FAIL_BIT);
            ESP_LOGE(TAG, "Failed to connect to AP after %d retries", WIFI_MAXIMUM_RETRY);
        }
    } else if (event_base == IP_EVENT && event_id == IP_EVENT_STA_GOT_IP) {
        ip_event_got_ip_t *event = (ip_event_got_ip_t *)event_data;
        ESP_LOGI(TAG, "Got IP:" IPSTR, IP2STR(&event->ip_info.ip));
        s_retry_num = 0;
        xEventGroupSetBits(s_wifi_event_group, WIFI_CONNECTED_BIT);
    }
}

// ---- init ----
esp_netif_init();
esp_event_loop_create_default();
esp_netif_create_default_wifi_sta();

wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
esp_wifi_init(&cfg);

// Regulatory: allow channels 1–13 (default US policy clips to 1–11)
wifi_country_t country = {
    .cc = "FI", .schan = 1, .nchan = 13, .policy = WIFI_COUNTRY_POLICY_AUTO};
esp_wifi_set_country(&country);

esp_wifi_set_ps(WIFI_PS_NONE);

esp_event_handler_instance_register(WIFI_EVENT, ESP_EVENT_ANY_ID, &event_handler, NULL, &any_id);
esp_event_handler_instance_register(IP_EVENT, IP_EVENT_STA_GOT_IP, &event_handler, NULL, &got_ip);

// ---- connect ----
wifi_config_t wifi_config = {
    .sta = {
        .threshold.authmode = WIFI_AUTH_WPA_WPA2_PSK,        // mixed-mode tolerant
        .pmf_cfg = {.capable = true, .required = false},     // 4-way handshake tolerance
        .scan_method = WIFI_FAST_SCAN,
        .sort_method = WIFI_CONNECT_AP_BY_SIGNAL,
    },
};
strncpy((char *)wifi_config.sta.ssid, ssid, sizeof(wifi_config.sta.ssid) - 1);
strncpy((char *)wifi_config.sta.password, password, sizeof(wifi_config.sta.password) - 1);
esp_wifi_set_mode(WIFI_MODE_STA);
esp_wifi_set_config(WIFI_IF_STA, &wifi_config);
esp_wifi_start();

Retry cap: #define WIFI_MAXIMUM_RETRY 5. Higher values just lengthen the failure path — they don't recover from a wrong SSID or password.

Canonical sdkconfig.defaults WiFi block

CONFIG_ESP_WIFI_STATIC_RX_BUFFER_NUM=10
CONFIG_ESP_WIFI_DYNAMIC_RX_BUFFER_NUM=32
CONFIG_ESP_WIFI_TX_BUFFER_TYPE=1
CONFIG_ESP_WIFI_DYNAMIC_TX_BUFFER_NUM=32
CONFIG_ESP_WIFI_AMPDU_TX_ENABLED=y
CONFIG_ESP_WIFI_AMPDU_RX_ENABLED=y
CONFIG_ESP_WIFI_AMSDU_TX_ENABLED=y
CONFIG_ESP_WIFI_NVS_ENABLED=y

Anti-pattern to remove: CONFIG_ESP_PHY_MAX_WIFI_TX_POWER=<N> (below default). Reducing TX power only loses link margin. It's sometimes justified as a brownout mitigation, but on a board with CONFIG_ESP_BROWNOUT_DET=n the brownout justification is moot — if brownout is disabled, you aren't going to get a brownout-triggered reset regardless of TX power. Only keep this setting if CONFIG_ESP_BROWNOUT_DET=y AND you've measured USB supply dips correlated with TX bursts.

Required CMakeLists.txt REQUIRES

REQUIRES esp_wifi nvs_flash esp_netif esp_event

Credentials contract

credentials.h must define:

#define WIFI_SSID "..."
#define WIFI_PASSWORD "..."

See sibling skill credential-setup for standardized credential handling (.example template, gitignore, pre-commit protection).

Disconnect reason → diagnosis

When the canonical event handler is in place and connection still fails, the log line WiFi disconnected. Reason: <N> (<name>) tells you what to fix:

Reason	Likely cause
WIFI_REASON_NO_AP_FOUND	SSID wrong, out of range, 5 GHz-only AP (ESP32/S3 is 2.4 GHz), country code blocks channel (fixed by canonical FI/1-13)
WIFI_REASON_AUTH_FAIL	Password wrong, or threshold.authmode stricter than AP advertises (canonical WPA_WPA2_PSK accepts both)
WIFI_REASON_ASSOC_FAIL	AP rejected (MAC filter, client cap)
WIFI_REASON_HANDSHAKE_TIMEOUT / WIFI_REASON_4WAY_HANDSHAKE_TIMEOUT	PMF mismatch, TX power too low, brownout during handshake
WIFI_REASON_BEACON_TIMEOUT	Link lost after connect (roaming, interference)

For hidden SSIDs, use .scan_method = WIFI_ALL_CHANNEL_SCAN and .bssid_set = 0 (known override; document in the project).

Audit process (audit <project-path>)

1. Read main/main.c and main/wifi_manager.c if present.
2. Read sdkconfig.defaults.
3. Read main/credentials.h.example (for contract check).
4. Compare against canonical; produce a drift table with file:line references.
5. Print the canonical snippets needed to converge.
6. Do not modify any files.

Drift check (compare against canonical values):

Check	Canonical
threshold.authmode	WIFI_AUTH_WPA_WPA2_PSK
pmf_cfg	{.capable = true, .required = false}
scan_method	WIFI_FAST_SCAN (unless hidden SSID)
sort_method	WIFI_CONNECT_AP_BY_SIGNAL
esp_wifi_set_country()	Called with FI/1/13/POLICY_AUTO
esp_wifi_set_ps(WIFI_PS_NONE)	Called
Disconnect reason logged	Yes, with name mapping
Retry cap	WIFI_MAXIMUM_RETRY = 5 (higher is drift)
CONFIG_ESP_PHY_MAX_WIFI_TX_POWER	Not set (unless justified by brownout+measurement)
CONFIG_ESP_WIFI_AMPDU_* / AMSDU_TX_ENABLED	y (ESP-IDF default; materially improves STA throughput)
SoftAP-on-S3 exception	If the project runs WIFI_MODE_AP on ESP32-S3, keep AMPDU off — see espressif/esp-idf#13508 (clients can't see the AP with AMPDU on)
CMakeLists.txt REQUIRES	Includes esp_wifi nvs_flash esp_netif esp_event

Apply process (apply <project-path>)

1. Detect structure: separate wifi_manager.{c,h} or inline in main.c?
   • If WiFi code is already self-contained in main.c (one handler + one init function), keep it inline and edit in place.
   • If WiFi code is spread across main.c OR the project is large enough that extracting clarifies it, create main/wifi_manager.{c,h} with the canonical shape (see robocar-unified/main/wifi_manager.{c,h} for exact file contents). Update main/CMakeLists.txt SRCS accordingly and replace inline WiFi code in main.c with wifi_init() + wifi_connect(WIFI_SSID, WIFI_PASSWORD) calls.
2. Apply targeted edits to reach canonical:
   • threshold.authmode → WIFI_AUTH_WPA_WPA2_PSK
   • Insert esp_wifi_set_country() call right after esp_wifi_init() (and before the config path — country affects scan).
   • scan_method → WIFI_FAST_SCAN (unless hidden SSID — verify with user).
   • Add reason-code logging in the STA_DISCONNECTED branch.
   • Ensure esp_wifi_set_ps(WIFI_PS_NONE) is present.
3. Update sdkconfig.defaults:
   • Add any missing entries from the canonical WiFi block.
   • Remove CONFIG_ESP_PHY_MAX_WIFI_TX_POWER=N unless brownout is enabled and the user confirms a measurement.
4. Ensure main/CMakeLists.txt REQUIRES includes the four components.
5. Delete the generated sdkconfig (ESP-IDF preserves existing values in sdkconfig and silently ignores new defaults — see .claude/rules/esp-idf-sdkconfig.md).
6. Report each file modified with before/after snippets, and cross-reference:
   • .claude/skills/sdkconfig-audit — further sdkconfig drift review
   • .claude/skills/credential-setup — credentials.h contract
   • .claude/rules/mdns-hostname.md — every STA project should also advertise an mDNS hostname

Output format

Bullet list of changes per file (use file:line form), with the delta between before/after for each. End with a "Next steps" block:

- Build: just <project>::clean && just <project>::build
- Flash + monitor: just <project>::flash-monitor
- On failure: the log will now show `WiFi disconnected. Reason: <N> (<name>)` —
  cross-reference the diagnosis table in this skill.