NodeBB

Welcome! Tell us about yourself Reply to this topic and introduce yourself: Name / Nickname College or Company What block you are on What you are building or want to build One thing you want to learn from Embiq We read every introduction. Looking forward to meeting you!

Welcome to your brand new NodeBB forum! This is what a topic and post looks like. As an administrator, you can edit the post's title and content. To customise your forum, go to the Administrator Control Panel. You can modify all aspects of your forum there, including installation of third-party plugins. Additional Resources NodeBB Documentation Community Support Forum Project repository

Block 2 — Embedded Core Resources All session content at docs.embiq.in/block2/ Session Topic 2.1.1 UART Deep Dive 2.1.2 SPI — Master/Slave, Timing 2.1.3 I2C — Addressing, Clock Stretch 2.1.4 ADC — Sampling, Noise 2.2.1 Interrupts & NVIC 2.2.2 GPIO Debounce 2.2.3 Timer & PWM 2.2.4 Interrupt Bugs 2.3.1 Why RTOS 2.3.2 FreeRTOS Tasks 2.3.3 Queues 2.3.4 Semaphores & Mutexes 2.3.5 Memory Management 2.3.6 RTOS Bugs 2.4.1 State Machines 2.4.2 HAL Design 2.4.3 Error Handling & Watchdog 2.4.4 Event-Driven Architecture

How to Submit Your Lab Every lab submission must include: Session number and lab name (e.g. "Lab 2.1.1 — UART Deep Dive") What it does — one paragraph description Code — paste your firmware using code blocks Evidence — serial output screenshot OR wiring photo OR video link What you learned — one sentence Format example: Lab: 2.1.1 — UART Two-Board Communication Description: Connected two ESP32 boards via UART. Board A sends a SensorReading_t struct every 2 seconds. Board B receives, parses, and prints. // your code here Serial output: [INF][1234] Received: temp=27.4, hum=62.1 What I learned: UART needs shared GND — forgot this and got garbage data for 20 minutes. Tag your post with the block tag e.g. block-2

Troubleshooting Index Search this page (Ctrl+F) for your error message before posting. GrapesIDE & Toolchain Error Cause Solution A fatal error occurred: Failed to connect to ESP32 Board not in flash mode Hold BOOT button while clicking Upload No serial port found Driver not installed Install CH340 or CP2102 driver Sketch too large Binary exceeds flash Change Partition Scheme to "No OTA (2MB)" 'x' was not declared in this scope Missing #include or typo Add the correct header file implicit conversion loses integer precision Type mismatch Cast explicitly or fix variable type warning: unused variable Variable declared but never used Remove or use the variable. Enable -Werror — this must be fixed ESP32 Hardware Error / Symptom Cause Solution ADC reads 0 or noise during WiFi ADC2 conflicts with WiFi Switch to ADC1 channels (GPIO32-39) GPIO reads random values (floating) No pull-up/pull-down Add 10kΩ pull-up or enable internal pull-up Device resets randomly Brownout — supply voltage too low Measure VCC under load. Use better USB cable/adapter Serial output garbled Wrong baud rate in monitor Match Serial.begin() rate exactly LED on but dim GPIO current limit exceeded Add current-limiting resistor FreeRTOS Error / Symptom Cause Solution Guru Meditation Error: Core panic'd Stack overflow, null deref, WDT Decode with addr2line — see Block 2 Crash Lab Task watchdog got triggered: taskName Task running without vTaskDelay Add vTaskDelay(pdMS_TO_TICKS(1)) in loop Device freezes randomly Deadlock between mutexes Check mutex acquisition order — always same order across tasks assert failed: queue.c Queue full with no space Increase queue size or consume faster Device reboots every N seconds WDT not being reset Add esp_task_wdt_reset() or vTaskDelay in busy tasks MQTT & Connectivity Error / Code Cause Solution PubSubClient state -2 (CONNECT_FAILED) Wrong credentials or broker down Check username/password/token PubSubClient state -4 (TIMEOUT) Wrong broker IP/port, firewall Verify host, port 8883 for TLS PubSubClient state 5 (UNAUTHORIZED) ACL blocked the topic Check topic matches your device_id exactly TLS certificate verify failed Wrong CA cert or device clock wrong Sync NTP before TLS connect TLS handshake timeout Heap too low for TLS Need >50KB free heap — check esp_get_free_heap_size() WiFi connects but MQTT fails TLS port blocked by ISP/router Try port 8083 (WS) or check firewall rules Messages not arriving QoS mismatch Check publisher and subscriber QoS match GrapesIoT Platform Symptom Cause Solution Device shows offline in dashboard LWT not configured or WiFi down Check MQTT connection and LWT topic OTA command sent but device ignores Device not subscribed to /down/# Check subscription in firmware Dashboard shows old data Retained message from previous session Clear retained by publishing empty payload Alarm not triggering Wrong field path in rule config Check dot-notation path matches payload key GrapesIDE Specific Issue Solution Autocomplete not working Restart IntelliSense: Ctrl+Shift+P → Reload Window Board not detected on Mac Allow USB accessories in System Settings → Privacy Build slow Exclude .pio folder from antivirus Last updated by instructor. Post below if you have a new error+solution to add.

Industry Problems Board Companies and startups post real engineering problems here. Students who solve them get: Recognition on their Embiq profile Direct introduction to the company Potential internship or job offer For companies: Post problems with the tag industry-problem. Include context, constraints, and what a good solution looks like. For students: Attempt problems publicly — show your reasoning, not just the answer. Multiple approaches welcome. This is the closest thing to a real technical interview the forum offers.