Using serial port on Raspberry Pi

Do I need any extra modules to send/receive strings down the Raspberry Pi serial pins, or is it all built into the OS?
I’ve seen mention of OS_SerialOp – does this do the job on the RPi?

Cheers,

Gerald.

PiSerial blockdrivers can be found here
http://www.tankstage.co.uk/Software/PiSerial.zip

Cheers Ronald – I’ll give it a go.

FYI as of today the development Pi ROMs should have working serial port support (OS_SerialOp + DeviceFS Serial1 interface). The Internal32 block driver (or similar) should work.

If people need to stick with PiSerial or other solutions then they should be able to *RMKill Serial to stop the OS’s driver from interfering with things

Is a PiSerial module aviable that works on a RPi2?

FYI as of today the development Pi ROMs should have working serial port support (OS_SerialOp + DeviceFS Serial1 interface). The Internal32 block driver (or similar) should work.

I have a socket with flying leads – how do I connect it, please, to use this facility? RPi2 B running 5.23 (10-Oct-16).

Could someone put a reference page up, please?

Following from Jeffery’s post above (10th October), I have finally got RISC OS onto my borrowed Pi3 (which has a Serial add-on card, plugging into the GPIO pins) and have knocked up the following programs:

REM>SerialReceive
PRINT"Waiting"
REM Set up the serial device
REM 8 bit word, 1 stop bit, no parity
SYS"OS_SerialOp",1,%000000
REM 9600 Baud rate
SYS"OS_SerialOp",5,0:REM RX
SYS"OS_SerialOp",6,0:REM TX
REM Read from the serial buffers
REPEAT
SYS"OS_SerialOp",4,0 TO ,c%
IF c%>31 AND c%<127 VDUc%
UNTILFALSE

and:

REM>SerialSend
REPEAT
INPUT"Text to send: “t$
REM Set up the serial device
REM 8 bit word, 1 stop bit, no parity
SYS”OS_SerialOp",1,%000000
REM 9600 Baud rate
SYS"OS_SerialOp",5,0:REM RX
SYS"OS_SerialOp",6,0:REM TX
REM Send the text to the serial buffers
FOR i%=1 TO LENt$
c%=ASCMID$(t$,i%,1)
SYS"OS_SerialOp",3,c%
NEXT
UNTILFALSE

but am unable to communicate with my Windoze 10 laptop using a USB to serial adapter and TeraTerm software. Am I missing something?
I’ve installed the October firmware update (low vector), and RISC OS 5.23 (5th December), and I’ve ensured that the serial modules are enabled.

Cheers,

Gerald.

Is the cable connected correctly? If it is, you should be able to measure several volts on each of pins 2 and 3 of the 9 pin D type connector, relative to pin 5. This is general advice for checking an EIA-232 connection, so it’s worth remembering.

If the cable is not correct, the chances are that only one of pins 2 and 3 will have significant voltage; this would indicate that you’ve got two transmitters trying to transmit to each other, and two receivers listening to each other – and that ain’t going to do anything useful. If it is like that, you could fix it by swapping pins 2 and 3 in the cable at one end.

Another thing to try: if you connect pins 2 and 3 together and run both your apps in task windows, you should be able to type to yourself.

Sorry, I forgot to mention that the serial cable is one I have previously used to get my work PC to talk to various bits of kit. However, I’ll stick a voltmeter on the pin and see if it shows anything. I was going to stick an oscilloscope on it.

Never thought of connecting pins 2 and 3 together…good idea – I’ll give it a go.

Sorry, I forgot to mention that the serial cable is one I have previously used to get my work PC to talk to various bits of kit.

While PC’s are DCE presentation and require a null modem cable (cross-over) to connect to another DCE device most of the dev board serial port presentations are DTE and therefore the connections are pin-to-pin.

Never thought of connecting pins 2 and 3 together

Normally you’d need to do some hardware handshake connections too but the Pi and various other dev boards don’t pass the handshake pins through and reply on software handshake.

One trick is to connect the output of your board to the serial input on a PC and run Putty at the right baud rate. All printable characters sent will appear in the putty console window.