2011-04-22 10:45 PM
Weired inverting problem
#rs232-transceiver #rs2322011-05-17 05:32 AM
Ok I have found what the problem is : see here
http://stackoverflow.com/questions/2633715/uart-speed-possibly-wrong
. So I am connecting USART3 to rs232 and that why the things get inverted. Now I have tried to use only UART4 but still the same problem. Is RS232 supported at all?Thanks,
Konstantin
2011-05-17 05:32 AM
You do have an RS232 Transceiver, don't you?
Note that RS232 uses bipolar voltage levels - nominally +/-12V. Therefore, you need an RS232 ''Transceiver'' to convert between a microcontroller's unipolar logic level (~3V for STM32) and RS232. The transceiver inverts the signals.2011-05-17 05:32 AM
Hi Neil,
I am just using simple PC port to connect to nothing special.
Thanks,
Konstantin
2011-05-17 05:32 AM
''I am just using simple PC port to connect to nothing special''
There is nothing ''special'' about an RS232 Transceiver - it is perfectly normal & standard and
must
be used whenever you want an RS232-to-logic-level interface. If you have connected the RS232 output from your PC's COM port directly to a pin on the STM32, then it is quite likely that you have blown-up the pin! If you look at the schematics of any devboard with an RS232 connection, you will see an RS232 transceiver being used. The MAX232 is a favourite RS232 transceiver for 5V systems; for 3V (such as the STM32), see MAX3232 Equivalents, Alternatives, and Substitutes are also widely available from many other manufacturers...2011-05-17 05:32 AM
Thanks,
Konstantin
2011-05-17 05:32 AM
''Ok I've missed that tiny (sic) part''
That's ''tiny'' in the same sense that ensuring you have a workign parachute is a ''tiny'' part of jumping out of an aeroplane...!!