Hands-on ESP32 and embedded engineering notes: real bugs, real fixes, and the reasoning behind hardware and firmware decisions.https://note.daojianmeng.top/https://note.daojianmeng.top/blog/choosing-2s-lipo-pack-small-esp32-robot/https://note.daojianmeng.top/blog/choosing-2s-lipo-pack-small-esp32-robot/Four N20 motors can stall at over 3 A combined, and a consumer LiPo cell with a 2 A protection board cannot deliver it. The budget, the four rejected options, and the 2S high-discharge pack that won.Sun, 06 Sep 2026 00:00:00 GMThttps://note.daojianmeng.top/blog/drv8833-vs-mx1508-n20-motors/https://note.daojianmeng.top/blog/drv8833-vs-mx1508-n20-motors/Two common dual H-bridge drivers compared for a small 7.4 V robot. The DRV8833 has real protection and rarely dies; the MX1508 sits too close to its voltage ceiling to trust with regenerative braking.Thu, 10 Sep 2026 00:00:00 GMThttps://note.daojianmeng.top/blog/esp-idf-windows-build-gotchas/https://note.daojianmeng.top/blog/esp-idf-windows-build-gotchas/Non-ASCII paths, file(GLOB) not seeing new sources, the wrong Python, Git Bash vs PowerShell, and a build directory that cannot be moved. Each one wasted an afternoon; here is the two-line diagnosis for each.Tue, 08 Sep 2026 00:00:00 GMThttps://note.daojianmeng.top/blog/esp32-failed-to-create-socket-lwip-max-sockets/https://note.daojianmeng.top/blog/esp32-failed-to-create-socket-lwip-max-sockets/A voice assistant that went silent after a firmware update turned out to be an exhausted LWIP socket pool. How to recognise it, why the symptom misleads, and the one Kconfig value to change.Sun, 23 Aug 2026 00:00:00 GMThttps://note.daojianmeng.top/blog/esp32-ota-silent-reset-task-watchdog/https://note.daojianmeng.top/blog/esp32-ota-silent-reset-task-watchdog/An OTA download that resets the board with no panic and no log line is almost always the task watchdog. The cure is a dedicated FreeRTOS task, not a bigger timeout.Thu, 20 Aug 2026 00:00:00 GMThttps://note.daojianmeng.top/blog/esp32-p4-c6-wifi-power-save-udp-latency/https://note.daojianmeng.top/blog/esp32-p4-c6-wifi-power-save-udp-latency/On the ESP32-P4-WIFI6 the radio lives on a separate C6 chip over SDIO, and the P4 cannot switch off its power saving. Here is how to get 10 ms UDP latency anyway.Wed, 26 Aug 2026 00:00:00 GMThttps://note.daojianmeng.top/blog/esp32-p4-gpio-stuck-at-1v2-ldo-power-domain/https://note.daojianmeng.top/blog/esp32-p4-gpio-stuck-at-1v2-ldo-power-domain/Four unrelated-looking motor and encoder bugs on an ESP32-P4 board turned out to be one missing line: GPIO45-54 sit on a power domain fed by the chip internal LDO, and nobody had turned it on.Tue, 18 Aug 2026 00:00:00 GMThttps://note.daojianmeng.top/blog/esp32-robot-control-mqtt-to-ipv6-udp/https://note.daojianmeng.top/blog/esp32-robot-control-mqtt-to-ipv6-udp/Cloud MQTT relay jitter kept tripping a 300 ms link-loss watchdog and made the motors stutter. A direct UDP channel over IPv6, discovered via the MQTT heartbeat, fixed it. Design notes and packet format.Sat, 29 Aug 2026 00:00:00 GMThttps://note.daojianmeng.top/blog/mecanum-wheel-mixing-esp32-firmware/https://note.daojianmeng.top/blog/mecanum-wheel-mixing-esp32-firmware/The app sends intent (strafe, drive, rotate); the ESP32 does the wheel mixing, gear limits, dead-band compensation and fail-safe. Why that split is right, and the numbers behind it.Tue, 01 Sep 2026 00:00:00 GMThttps://note.daojianmeng.top/blog/mpu6050-is-actually-mpu6500-who-am-i-ad0/https://note.daojianmeng.top/blog/mpu6050-is-actually-mpu6500-who-am-i-ad0/A cheap IMU board labelled MPU6050 returned WHO_AM_I = 0x70, and a floating AD0 pin made it disappear from the bus entirely. How to write a driver that copes with both, plus the streaming design that gets 44 Hz attitude over UDP.Fri, 04 Sep 2026 00:00:00 GMT