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发表于 2024-9-30 09:57:06
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本帖最后由 jmg 于 2024-9-30 11:41 编辑
Perhaps add a inverter so user can optionally connect 89C52 RESET to Ai8051U /RST ?
If you want to route XTAL1, XTAL2 you could add GND / Guard traces to protect from P37 and between XTAL1,XTAL2 traces where it can fit.
Maybe smaller TACT buttons can give more room for GND traces?
Another clocking option, would be to allow an optional footprint for a part like 1XXA26000MAA KDS Daishinku 26MHz ±2ppm SMD-2520 VC ±9ppm Aging ±1ppm/yr (lcsc C132298 )
The clipped sine out AC couples thru 1nF to XTALin, and the VC pin can have optional R+C pads for PWM DAC support.
That covers very high precsion timing designs like frequency counters which are good teaching examples.
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