缘由

玩arduino UNO时发现用avrdude下载和用arduino IDE下载总是出现卡死下载失败

echo "where avrdude"
echo "d:\\WinAVR-20100110\\bin\\avrdude.exe"
avrdude -p m328p -c arduino -P COM18 -b 115200 -U flash:w:default\\frser.hex
pause

arduino下载卡死通信停止.png

即使下载成功，但是当做串口通信，数据量大时，就出现偶尔的通信异常导致卡死，

原因排查

某宝16.5块买的，无技术支持；给5V电源加上电解滤波电容，无效；
板arduino放冰箱低温几分钟下载测试，下载卡死概率增高；
用风筒吹加热，下载反而正常了；
发现USB转串口部分，晶振无任何标记，芯片苏任何丝印，电脑设备管理居然显示CH340;
刚开始还以为MEGA328芯片通信死机，后来排查，用一条PL2303线替换原机测试，通信正常。

开始改造

搜出元件盒子发现之前买的CH340N,SOP8封装，查找资料，
- CH340N芯片官网
  - http://www.wch.cn/product/CH340.html
- CH340N规格书
  - https://atta.szlcsc.com/upload/public/pdf/source/20200819/C84681_ADBED554CE321879DBD6B1D06488689C.pdf','0204D0F8DFEAAC23296C67311B688FC3','new_pdf_doc_pdf
- 驱动下载网址
  
   http://www.wch.cn/downloads/CH341SER_EXE.html
拆晶振，拆无丝印的山寨CH340驱动的芯片，拆假的晶振负载电容C21;
根据CH340N对比分析走线布局和准备
改造后实物图

重新烧录成功

avrdude -p m328p -c arduino -P COM18 -b 115200 -U flash:w:default\\frser.hex

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.02s

avrdude: Device signature = 0x1e950f
avrdude: NOTE: FLASH memory has been specified, an erase cycle will be performed

         To disable this feature, specify the -D option.
avrdude: erasing chip
avrdude: reading input file "default\\frser.hex"
avrdude: input file default\\frser.hex auto detected as Intel Hex
avrdude: writing flash (3334 bytes):

Writing | ################################################## | 100% 0.93s

avrdude: 3334 bytes of flash written
avrdude: verifying flash memory against default\\frser.hex:
avrdude: load data flash data from input file default\\frser.hex:
avrdude: input file default\\frser.hex auto detected as Intel Hex
avrdude: input file default\\frser.hex contains 3334 bytes
avrdude: reading on-chip flash data:

Reading | ################################################## | 100% 0.77s

avrdude: verifying ...
avrdude: 3334 bytes of flash verified

avrdude: safemode: Fuses OK

avrdude done.  Thank you.

缘由

原因排查

开始改造

重新烧录成功

后记