Also are you using your original HC126 cct with enable/disable TxD/RxD, or your new version with Rpi 3V3/5V0 level shift up? My cct does not sue any GPIO to pull up HC03 […]

@AdrianMaire Ha, I have not thought about it too carefully. I simple mindedly thought that higher clock speed means less time each instruction. So 2GHz CPU should run instructions two times faster […]