I am designing a Serial to Parallel converter with PIC16f84A micro-controller. Where I am going to use pin RA0 for data input, RA1 for clock input and RB0 to RB7 for parallel data output from MCU. Now I cant figure out that how to produce clock signals with data signals, since the serial port RS232 have only one pin for data transmission, and also Hyper Terminal program only use pin no. 3 for data transmission only.
Electronic – How to produce clock signals with data on serial port
communicationmicrocontrollerserial
Related Solutions
The sparkfun is a bit of a hack device that doesn't actually do proper RS-232 level shifting. Instead it uses the voltages from the other end to charge capacitors to use for the sending voltages - a clever idea, but I can forsee flaws if the other end isn't sending high enough voltages...
I would recommend ditching the sparkfun and using a MAX232 or similar device to do real level shifting.
Here is how I would suggest going about debugging this problem:-
Check the connections.. if you've mixed up signal ground and chassis ground (shield) you could get funny behavior just like you describe. Pin 7 on the DB-25 is the one you want to connect to DE-9 pin 5. I'll assume you're using a commercial adapter/cable or have one wired like this.
Maybe check the transmit out line to ensure it's idling at -12 ( < -3 anyway).
Make sure the instrument is set to RS-232, and not current loop (Jumper 7,8 and 1,2).
Try the most common serial port setting (9600/8-N-1), 9600 baud, NO parity, 1 stop bit switch 1, 2, 3 OFF switch 4, 5 ON switch 6 ON switch 7, 8 ON
Make SURE you understand which is 'OFF' and which is 'ON'. Don't laugh, I've seen this happen more than once, and some types of DIP switches are kind of ambiguously marked. If in doubt, an ohmmeter across the switch.. in fact you could check all of the switches to ensure they're working.
I like Realterm as a terminal program. It's free, and easy to change the parameters. Try it on something known working first of course, and look for an online tutorial. Really worth it.
If still gibberish after that, get a scope screen cap or photo and post it.
If you have a continuing need for a logic analyzer, this one is very cheap and relatively useful. Not as good as my Tektronix boat anchor, but this one will fit in a coat pocket. But I'd get a scope first if you don't have one. Even the worst scope is better than nothing.
Related Topic
- Electronic – Understanding Clock Input Signal
- Serial Data Input through Microcontroller to Output Voltage
- Electronic – Multiple out signals with single clock
- Electronic – Interfacing an inductive proximity sensor with the Pin RA0 of PIC16F690
- Electronic – Confusion with serial communication standards when sending sync serial data to a PC thorugh its serial port
Best Answer
RS232 does not involve a transmitted clock; the reciever must synchonize to the transmission using the start bit, and the baud rate has to be agreed in advance (or inferred from a sequence of characters transmitted, sometimes called "auto-baud")
(If that PIC has a UART, you could use it to make this project easier)