本人使用自己画的板子，用usart1的pa9和pa10在stm32cubeprogrmmer中进行串口连接，也保留了swd串口调试接口，但始终无法正确连接，报错如下：00:37:16:773 : RTS low 00:37:16:774 : DTR Low 00:37:16:833 : Serial Port cu.usbmodem0000637289221 is successfully opened. 00:37:16:833 : Port configuration: parity = even, baudrate = 115200, data-bit = 8, stop-bit = 1.0, flow-control = off 00:37:16:833 : No Init bits value is : 0 00:37:16:833 : Sending init command: 00:37:16:833 : #byte 0x7F sent successfully to target 00:37:18:834 : Wait ends after 1 loop, dataready = 0, delay = 2001 00:37:18:835 : Timeout error occured while waiting for acknowledgement. 00:37:18:835 : No response from target received 00:37:18:836 : Retrying UART init connection... 00:37:18:836 : #byte 0x7F sent successfully to target 00:37:18:847 : Wait ends after 1 loop, dataready = 1, delay = 11 00:37:18:848 : #ack Received response from target: 0x1f 00:37:18:848 : Activating device: OK 00:37:18:848 : Board : -- 00:37:18:848 : Sending GetID command and its XOR: 00:37:18:848 : #byte 0x02 sent successfully to target 00:37:18:848 : #byte 0xFD sent successfully to target 00:37:18:859 : Wait ends after 1 loop, dataready = 1, delay = 11 00:37:18:859 : #ack Received response from target: 0x79 00:37:18:859 : Received 4 data bytes from target : 0x01045079 00:37:18:859 : Chip ID: 0x450 00:37:18:859 : Sending Get command and its XOR: 00:37:18:860 : #byte 0x00 sent successfully to target 00:37:18:860 : #byte 0xFF sent successfully to target 00:37:18:874 : Wait ends after 1 loop, dataready = 1, delay = 14 00:37:18:874 : #ack Received response from target: 0x79 00:37:18:874 : Received 1 data bytes from target : 0x0b 00:37:18:874 : size of bytes in the response: 11 00:37:18:874 : Received 13 data bytes from target 00:37:18:874 : Full received response: 0b31000102112131446373829279 00:37:18:874 : BootLoader protocol version: 3.1 00:37:18:874 : #byte 0x11 sent successfully to target 00:37:18:874 : #byte 0xEE sent successfully to target 00:37:19:000 : #data sent successfully to target: 0x0800000008 00:37:20:011 : Sending GetID command and its XOR: 00:37:20:011 : #byte 0x02 sent successfully to target 00:37:20:011 : #byte 0xFD sent successfully to target 00:37:20:020 : Wait ends after 1 loop, dataready = 1, delay = 8 00:37:20:020 : #ack Received response from target: 0x1f 00:37:20:020 : Response received from device: NACK 00:37:20:020 : Error: GETID command not acknowledged! 00:37:20:145 : Reemission of GetID command 00:37:20:146 : Sending GetID command and its XOR: 00:37:20:146 : #byte 0x02 sent successfully to target 00:37:20:146 : #byte 0xFD sent successfully to target 00:37:20:161 : Wait ends after 1 loop, dataready = 1, delay = 14 00:37:20:162 : #ack Received response from target: 0x79 00:37:20:163 : Received 4 data bytes from target : 0x01045079 00:37:20:205 : #byte 0x11 sent successfully to target 00:37:20:205 : #byte 0xEE sent successfully to target 00:37:20:308 : #data sent successfully to target: 0x0800000008 00:37:21:310 : Sending Read command and its XOR: 00:37:21:310 : #byte 0x11 sent successfully to target 00:37:21:311 : #byte 0xEE sent successfully to target 00:37:21:321 : Wait ends after 1 loop, dataready = 1, delay = 11 00:37:21:322 : #ack Received response from target: 0x1f 00:37:21:322 : Response received from device: NACK 00:37:21:322 : Error: READ command not acknowledged at address: 0x8000000 00:37:21:322 : Database: Config 0 is active. 00:37:21:323 : Sending GetID command and its XOR: 00:37:21:324 : #byte 0x02 sent successfully to target 00:37:21:324 : #byte 0xFD sent successfully to target 00:37:21:337 : Wait ends after 1 loop, dataready = 1, delay = 14 00:37:21:337 : #ack Received response from target: 0x79 00:37:21:337 : Received 4 data bytes from target : 0x01045079 00:37:22:582 : Sending GetID command and its XOR: 00:37:22:582 : #byte 0x02 sent successfully to target 00:37:22:582 : #byte 0xFD sent successfully to target 00:37:22:582 : Wait ends after 1 loop, dataready = 1, delay = 14 00:37:22:582 : #ack Received response from target: 0x79 00:37:22:582 : Received 4 data bytes from target : 0x01045079 00:37:22:582 : #byte 0x11 sent successfully to target 00:37:22:582 : #byte 0xEE sent successfully to target 00:37:22:582 : #data sent successfully to target: 0x0800000008 00:37:22:582 : UPLOADING OPTION BYTES DATA ... 00:37:22:583 : Bank : 0x00 00:37:22:583 : Address : 0x5200201c 00:37:22:583 : Size : 308 Bytes 00:37:22:583 : Sending Read command and its XOR: 00:37:22:583 : #byte 0x11 sent successfully to target 00:37:22:583 : #byte 0xEE sent successfully to target 00:37:22:583 : Wait ends after 1 loop, dataready = 1, delay = 10 00:37:22:583 : #ack Received response from target: 0x1f 00:37:22:583 : Response received from device: NACK 00:37:22:583 : Error: READ command not acknowledged at address: 0x5200201C 00:37:22:583 : Error: Uploading Option Bytes bank: 0 failed 00:37:22:610 : Error: Initializing the Option Bytes failed 00:37:22:639 : UART PORT CLOSE 00:37:22:639 : Disconnected from device. 00:37:31:421 : Error: Connection to target must be established before performing the erase command. 00:37:31:532 : Disconnected from device.

本人的mcu是在嘉立创买的，应该不存在盗版二手的问题，想问下这是被读保护了吗，是几级呢？有什么解决方案吗

你这贴出来的信息跟一锅粥一样的，

感觉你的bootloader已经跑起来了，也执行了部分命令，的确是像读保护了。

你不是预留了SWD口吗？用STM32CubeProgrammer连接看看，RDP的等级，如果是L1倒是

小问题，修改为RDP0即可，如果L2就换个芯片吧。

可以尝试用SWD 口将芯片的optionbyte 设置成相应模式。另外也可以读到内部的版本信息看看。


排查一下硬件，保证可以有升级功能的 RX 脚不要出现扰动信号（尝试接个上拉电阻）。