max232 and pic16f877a

[Eng.Abbasi]

hello all

im using USART module in pic16f877a to transfer data to the serial port of my pc . first do i have to use max232 to make the preparation for the PC port or not,
second i used value d'31' in the BRGH register to set baud-rate 9600 was it wrong?

and thanx for all

 

[Papabravo]

The serial port of a PC does use RS-232 levels so I would say that you need the transceiver. The value in the BRGH register depends on the frequency of operation of the PIC, so the value you used may or may not be correct. What does the datasheet say?

 

[Eng.Abbasi]

thnx Mr. the pic16f877a and the oscillater is 20Mhz

 

[Nigel Goodwin]

Check my tutorials, the last of the RS232 ones uses the hardware USART at 9600 baud with a 20MHz crystal.

 

[Eng.Abbasi]

ok it was written in the data sheet but my mistake is the max232
129 at high
31 at low

 

[Mike - K8LH]

You can download an Excel 2000 SPBRG Calculator spreadsheet from this thread on Forum Microchip; **broken link removed**

There's also a single-file stand-alone application (screen shot below) you can download from that same thread.

Regards, Mike

**broken link removed**