From 05ceca02ab498e8a157784b606b92d38b9fa5b67 Mon Sep 17 00:00:00 2001
From: Bob <bob@umbernetworks.com>
Date: Fri, 21 Nov 2025 10:53:44 -0800
Subject: [PATCH] more on CSI and S3

---
 CMakeLists.txt                 |  2 +-
 components/wifi_cfg/wifi_cfg.c | 53 +++++++++++++++++++++++++---------
 2 files changed, 40 insertions(+), 15 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9673e51..ec3d59a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -5,4 +5,4 @@ cmake_minimum_required(VERSION 3.22)
 include($ENV{IDF_PATH}/tools/cmake/project.cmake)
 # "Trim" the build. Include the minimal set of components, main, and anything it depends on.
 idf_build_set_property(MINIMAL_BUILD ON)
-project(hello_world)
+project(CSI)
diff --git a/components/wifi_cfg/wifi_cfg.c b/components/wifi_cfg/wifi_cfg.c
index 009801e..bc0b0bb 100644
--- a/components/wifi_cfg/wifi_cfg.c
+++ b/components/wifi_cfg/wifi_cfg.c
@@ -206,24 +206,33 @@ bool wifi_cfg_apply_from_nvs(void) {
     }
 
     ESP_ERROR_CHECK( esp_wifi_set_mode(WIFI_MODE_STA) );
-    // Enable WiFi 6 (802.11ax) and all protocols for best compatibility
+
+    // Configure WiFi protocols based on chip capabilities
+#if CONFIG_IDF_TARGET_ESP32C5 || CONFIG_IDF_TARGET_ESP32C6
+    // Dual-band chips (2.4GHz + 5GHz support)
     wifi_protocols_t protocols = {
-        // 2.4 GHz: b/g/n/ax
+        // 2.4 GHz: b/g/n (no ax for CSI compatibility)
         .ghz_2g = WIFI_PROTOCOL_11B |
-        WIFI_PROTOCOL_11G |
-        WIFI_PROTOCOL_11N,
-        // Restrict protocols so CSI can work:
-        //  - CSI on ESP32-C5 is only supported on 2.4 GHz HT (11n), not HE (11ax)
-        //  WIFI_PROTOCOL_11AX,
+                  WIFI_PROTOCOL_11G |
+                  WIFI_PROTOCOL_11N,
         // 5 GHz: a/n/ac/ax
         .ghz_5g = WIFI_PROTOCOL_11A |
-        WIFI_PROTOCOL_11N |
-        WIFI_PROTOCOL_11AC |
-        WIFI_PROTOCOL_11AX,
-        // .ghz_6g will be zero-initialized (not used on C5)
+                  WIFI_PROTOCOL_11N |
+                  WIFI_PROTOCOL_11AC |
+                  WIFI_PROTOCOL_11AX,
     };
-
     ESP_ERROR_CHECK( esp_wifi_set_protocols(WIFI_IF_STA, &protocols) );
+#else
+    // Single-band chips (2.4GHz only) - ESP32, ESP32-S2, ESP32-S3, ESP32-C3, etc.
+    // Use legacy API for 2.4GHz-only chips
+    uint8_t protocol_bitmap = WIFI_PROTOCOL_11B | WIFI_PROTOCOL_11G | WIFI_PROTOCOL_11N;
+    ESP_ERROR_CHECK( esp_wifi_set_protocol(WIFI_IF_STA, protocol_bitmap) );
+
+    // Warn if user requested 5GHz on a 2.4GHz-only chip
+    if (strcmp(band, "5G") == 0) {
+        ESP_LOGW(TAG, "5GHz requested but this chip only supports 2.4GHz - using 2.4GHz");
+    }
+#endif
 
     ESP_ERROR_CHECK( esp_wifi_set_config(WIFI_IF_STA, &wcfg) );
 
@@ -237,7 +246,8 @@ bool wifi_cfg_apply_from_nvs(void) {
     if (err2 != ESP_OK && err2 != ESP_ERR_INVALID_STATE) { ESP_ERROR_CHECK(err2); }
 
     // Set bandwidth AFTER WiFi is started but BEFORE connect
-    // For ESP32-C5 dual-band, use esp_wifi_set_bandwidths() with struct
+#if CONFIG_IDF_TARGET_ESP32C5 || CONFIG_IDF_TARGET_ESP32C6
+    // Dual-band chips use struct-based API
     wifi_bandwidths_t bandwidths = {
         .ghz_2g = WIFI_BW_HT20,
         .ghz_5g = WIFI_BW_HT20
@@ -251,11 +261,26 @@ bool wifi_cfg_apply_from_nvs(void) {
         ESP_LOGI(TAG, "Setting bandwidth to HT20 (20MHz) for both bands");
     }
 
-    // Use dual-band API with struct pointer
     err2 = esp_wifi_set_bandwidths(WIFI_IF_STA, &bandwidths);
     if (err2 != ESP_OK) {
         ESP_LOGW(TAG, "Failed to set bandwidths: %s", esp_err_to_name(err2));
     }
+#else
+    // Single-band chips (2.4GHz only) use legacy API
+    wifi_bandwidth_t bandwidth = WIFI_BW_HT20;
+
+    if (strcmp(bw, "HT40") == 0) {
+        bandwidth = WIFI_BW_HT40;
+        ESP_LOGI(TAG, "Setting bandwidth to HT40 (40MHz) for 2.4GHz");
+    } else {
+        ESP_LOGI(TAG, "Setting bandwidth to HT20 (20MHz) for 2.4GHz");
+    }
+
+    err2 = esp_wifi_set_bandwidth(WIFI_IF_STA, bandwidth);
+    if (err2 != ESP_OK) {
+        ESP_LOGW(TAG, "Failed to set bandwidth: %s", esp_err_to_name(err2));
+    }
+#endif
 
     err2 = esp_wifi_connect();
     if (err2 != ESP_OK && err2 != ESP_ERR_WIFI_NOT_INIT && err2 != ESP_ERR_INVALID_STATE) { ESP_ERROR_CHECK(err2); }