# DietPi mcu Permission Denied **URL:** \ **Category:** General Discussion\ **Created:** [January 19, 2026, 10:53pm UTC](https://klipper.discourse.group/t/dietpi-mcu-permission-denied/25532 "2026-01-19T22:53:26Z")\ **Posts on this page:** 1\ **Showing post:** 21
**Author:** ![cardoc](https://avatars.discourse-cdn.com/v4/letter/c/ec9cab/32.png) [@cardoc](https://klipper.discourse.group/u/cardoc)\ **Post date:** [January 20, 2026, 7:52pm UTC](https://klipper.discourse.group/t/dietpi-mcu-permission-denied/25532/21 "2026-01-20T19:52:57Z")
If I’m not mistaken the error “Timeout on connect → Serial connection closed” really means Klipper is - Open USB serial port - Send the very first packet: identify - Receive nothing - Wait 1 second - Retry - Eventually give up and close the port If I’m correct that means klipper firmware is not running on the MCU. The creality 4.2.2 board is notoriously dificult to flash. > [@Ender 3 v2 board 4.2.2, not able to flash Klipper firmware](https://klipper.discourse.group/t/ender-3-v2-board-4-2-2-not-able-to-flash-klipper-firmware/24140): > > Basic Information: Printer Model: Creality Ender 3 V2 MCU / Printerboard: STM32F103 RET6 Host / SBC Samsung S10 klippy.log Describe your issue: I’ve been trying to flash Klipper firmware on my printer, which uses a Creality 4.2.2 board, but I haven’t had any success using the settings shown in the image: I’m using an 8GB Kingston SD card formatted to FAT32 with the SD Card Formatter tool. This same card has successfully flashed Marlin firmware b… Add to that the GD32F330 is not a “mainstream” MCU. > [@Support for new Creality boards 4.2.2 with GD32F303](https://klipper.discourse.group/t/support-for-new-creality-boards-4-2-2-with-gd32f303/3016/7): > > Follow the directions at the top of [klipper/printer-creality-ender3-v2-2020.cfg at master · Klipper3d/klipper · GitHub](https://github.com/Klipper3d/klipper/blob/master/config/printer-creality-ender3-v2-2020.cfg) . In practice, the gd32 chip works the same as the stm32f103. > > -Kevin --- _[View the full topic](https://klipper.discourse.group/t/dietpi-mcu-permission-denied/25532)._