{:4_250:}
本帖最后由 jmg 于 2024-1-25 16:53 编辑
Add crystal oscillator frequency stabilization, and the RX2 pin serves as both RX2 output and frequency measurement input (use a small toggle switch).
Good ideas, but the existing STC USB-2UART board already has a 22.1184MHz crystal fitted, so this does not improve much. (I measure about -50ppm too slow)
Suggest you look to fit a TCXO oscillator for better frequency precision ?
This can AC couple through 1nF to XTALI pin
Common TCXO values are 19.2M, 26.000M, 38.4M, 52MHz (overclocked)
lcsc examples:
KDS Daishinku 1XXA26000MAA VC-TCXO 26MHz voltage trim
TG2016SMN 38.4000M-MCGNNM3 Seiko Epson 2.8V~3.3V Clipped Sine Wave ±500ppb SMD2016-4P
If you want to extend the frequency counter MHz-in range, small logic parts like 74AHC1G4210GW can extend > 100MHz
(or even ~~STC8H2K08U-45I-SOP16~~, it's cheap enough to replace logic. Oops, needs to be STC8H2K08U-45I-TSSOP20 (same price) to have a XTALI pin, for divider input. XTALI is missing on SOP16 )
jmg 发表于 2024-1-25 13:23
Good ideas, but the existing STC USB-2UART board already has a 22.1184MHz crystal fitted, so this d ...
大佬，俺不懂英语的
热烈支持，能把PCB项目分享给大家吗，都来玩玩
搞得很好看啊！赞！
xxkj2010 发表于 2024-1-25 20:41
大佬，俺不懂英语的
{:4_245:}还是咱们国语交流起来更方便
国学芯用 发表于 2024-2-4 11:07
还是咱们国语交流起来更方便
是的，用国语方便，包括stc官方例程，我都喜欢看中文注释的。一看到英文注释，就觉得学不下去
请问楼主：STC8H8K64U有4个串口，搞成USB转4串口可行吗？
感谢分享，有PCB链接吗
hhh402 发表于 2024-2-5 01:12
请问楼主：STC8H8K64U有4个串口，搞成USB转4串口可行吗？
没有试过，也不知道怎么处理，这个问题得问stc工程师他们。