Pic16f88

[Maurice]

Hi,
Can somebody tell me if the internal 8MHz oscillator is accurate enough to drive proper RS232 timings out of the 16F88? Is it also possible to use it when I'm using the normal serout2/serin2 from a general I/O pin of that chip.

thanks, Maurice

[mister_e]

depending of your baudrate, temperature change, and few others... it can be accurate enough to work.

Why using SERIN/SEROUT on a F88 when you can use the internal USART capability with HSERIN/HSEROUT instead???

[Maurice]

Hi Mr_e,
thanks again for the response on the RS232 question. It sounds to me that it may be a bit dodgy to use the internal oscillator and the old RS232 methods. Guess I'll have to bite the bullet and learn about the real serial ports on the '88. Its just that I had some old code I can pop into the '88 and no further thought needed. Can the official hardware method be any better for accuracy since it must use the same internal oscillator? (?)

thanks again

Spencer

[mister_e]

the internal one is still an RC oscillator that shift with the ambient temperature. It can work fine or no. For solid and safe serial communication using external crystal (not ceramic resonator) is the way to go. At slow baudrate like 2400,4800, INTRC will be good enough IMO.

The use of internal USART, depending of the register setting, can provide much accuracy and faster baudrate on slower crystal frequency... see usart SPBRG setting. Another main advantage, to name only one, is to use less of that precious code space.