From 21bfc93676c56e2265f330170d319da2c480987d Mon Sep 17 00:00:00 2001
From: lonkaars <loek@pipeframe.xyz>
Date: Thu, 9 May 2024 15:18:51 +0200
Subject: working FreeRTOS + lwIP blink/wifi connect example again

---
 main/init.cpp | 30 ++++++++++++++++++++++++++----
 main/init.h   | 35 ++++++++++++++++++++++++++++++++++-
 main/main.cpp | 27 ++++++++++++++++-----------
 3 files changed, 76 insertions(+), 16 deletions(-)

diff --git a/main/init.cpp b/main/init.cpp
index 425f591..48f3774 100644
--- a/main/init.cpp
+++ b/main/init.cpp
@@ -1,9 +1,15 @@
 #include "config.h"
 #include "init.h"
 
+#include <FreeRTOS.h>
+#include <task.h>
+#include <event_groups.h>
+
 #include <pico/stdio.h>
 #include <pico/cyw43_arch.h>
 
+EventGroupHandle_t init_complete;
+
 static void init_stdio() {
 	stdio_init_all();
 }
@@ -20,13 +26,29 @@ static void init_wifi() {
 	if (cyw43_arch_wifi_connect_timeout_ms(CONF_NET_SSID, CONF_NET_PASS, CYW43_AUTH_WPA2_AES_PSK, CONF_NET_CONN_TIMEOUT))
 		panic("cyw43_arch_wifi_connect failed\n");
 
-	// TODO: announce hostname
+	// TODO: announce hostname(?)
 }
 
 void init() {
+	init_complete = xEventGroupCreate();
+
+	// used for debug `printf` and `panic` on errors
 	init_stdio();
-	init_cyw34();
-	init_wifi();
-	// TODO: initialize i2c
+
+	// defer other initialization until the task scheduler is running (important)
+	xTaskCreate((TaskFunction_t) [](void*) {
+		init_cyw34();
+		init_wifi();
+		// TODO: initialize i2c
+
+		xEventGroupSetBits(init_complete, 1);
+
+		// delete self
+		vTaskDelete(NULL);
+	}, "init", configMINIMAL_STACK_SIZE, NULL, tskIDLE_PRIORITY + 4, NULL);
+}
+
+void await_init() {
+	xEventGroupWaitBits(init_complete, 1, pdFALSE, pdFALSE, portMAX_DELAY);
 }
 
diff --git a/main/init.h b/main/init.h
index 1f931dc..97b2e20 100644
--- a/main/init.h
+++ b/main/init.h
@@ -1,5 +1,38 @@
 #pragma once
 
-/** @brief initialize all peripherals on the pico */
+#include <FreeRTOS.h>
+#include <event_groups.h>
+
+/**
+ * @brief init function complete event group handle
+ *
+ * This is required to make sure the main task waits until initialization is
+ * complete. Due to the combination of FreeRTOS + lwIP, the initialization
+ * should be done while the task scheduler is running. Specifically the
+ * cyw43_arch_init functions make the pico hang indefinitely when used while
+ * the task scheduler is not running.
+ *
+ * @note `init_complete` only utilizes LSB, so `uxBitsToWaitFor` should always
+ * be set to *1*
+ */
+extern EventGroupHandle_t init_complete;
+
+/**
+ * @brief initialize all peripherals on the pico
+ *
+ * This function only synchronously initializes the standard input/output (used
+ * for `printf` and `panic`), and queues all other types of initialization in
+ * the `init` task using FreeRTOS.
+ *
+ * @note Tasks dependent on the wifi being initialized should use the
+ * `init_complete` event group to wait for initialization to complete!
+ */
 void init();
 
+/**
+ * @brief block task until all initialization is complete
+ *
+ * utility function, see above comments
+ */
+void await_init();
+
diff --git a/main/main.cpp b/main/main.cpp
index ace9f01..c97a808 100644
--- a/main/main.cpp
+++ b/main/main.cpp
@@ -7,11 +7,13 @@
 #include "config.h"
 #include "init.h"
 
-#include <lwip/sockets.h>
-#include <lwip/sys.h>
-#include <lwip/opt.h>
+// #include <lwip/sockets.h>
+// #include <lwip/sys.h>
+// #include <lwip/opt.h>
 
 void blink_task() {
+	await_init(); // `blink_task` uses GPIO
+
 	while (true) {
 		cyw43_arch_gpio_put(LED_PIN, 0);
 		vTaskDelay(250 / portTICK_PERIOD_MS);
@@ -20,18 +22,21 @@ void blink_task() {
 	}
 }
 
+void test_task() {
+	int i = 0;
+	while (true) {
+		// stdio is initialized synchronously, so no `await_init` is needed
+		printf("hello #%d...\n", ++i);
+		vTaskDelay(1000 / portTICK_PERIOD_MS);
+	}
+}
+
 int main() {
 	init();
 
-	for (int i = 5; i > 0; i--) {
-		printf("starting in %d...\n", i);
-		sleep_ms(1000);
-	}
-
-	// this should compile but not work
-	lwip_socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
+	xTaskCreate((TaskFunction_t) blink_task, "blink", configMINIMAL_STACK_SIZE, NULL, tskIDLE_PRIORITY + 2, NULL);
+	xTaskCreate((TaskFunction_t) test_task, "test", configMINIMAL_STACK_SIZE, NULL, tskIDLE_PRIORITY + 2, NULL);
 
-	xTaskCreate((TaskFunction_t) blink_task, "blink", 128, NULL, 1, NULL);
 	vTaskStartScheduler();
 }
 
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