rs232 on 18f4520

james · Guest

Hi, looking for some pointers / things to check with a problem I have.
I'm running rs232 via max3232 on and 18f4520.
I have a basic program running, and can send from the pic to hyper-terminal (windows).
When I try and send something back from hyper-terminal, then return it via the pic to ensure both tx and rx work, I get hieroglyphics back... i.e, when I send a key press from the keyboard back to the pic, I used getc command, assign data to a char, then do a printf, and get junk back at the hyper terminal.

any ideas?

thanks

james

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Try a simple test program, as shown below. If your crystal is above
4 MHz, then change the fuse from XT to HS and also edit the #use delay
statement for the correct frequency.

james · Guest

Thanks for your very quick reply,
I am unable to test anything until Thursday, am away from the workshop,

Thanks for your help so far and I will post again after I tried your suggestion.

Thank you again.

James

asmallri · Joined: 12 Aug 2004 Posts: 1634 Location: Perth, Australia

check the baud rate, number of start bits, data bits, stop bits and parity match. Most text type applications use 1 start, 1 stop, 8 data, no parity.

If you are using your own hardware then check that the max chip is generating the +10 and -10 volt levels. When the PIC is not transmitting you should be able to measure -10 volts on the transmit output from the MAX chip to the PC
_________________
Regards, Andrew

http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!!