To Sanjeev Kumar

I recently received a kit for the C8051F330/331 from Cygnal (c8051f330dk)
In addition, I have some spare c8051f330 and I tested one in a 3.3—5V environment.
I put a MAX232 at 5V and the processor at 3V.

I configured P0.4 and P0.5 as open drain and I put two 2.7kohm resistors from those pins to +5V.

I used the internal 24.5MHz clock without tuning.

It works well from 9600 to 115 200 bps.
I also programmed the timer1 with 0xcb value for 230400 bps.
I did not test this speed as my computer doesn’t accept it but accordingly to my oscilloscope’s screen the waveforms are ok.

I had only a bad surprise: TX and RX cannot be routed by the crossbar; the pins are always p0.4 and p0.5 .
As you probably guess, I didn’t carefully read the data sheet (witch is very explanatory) and I designed the PCB in advance so I had to scratch it.

However, the signal’s levels are good.

Cristian