bakalarska_praca/externe_kniznice/teuniz_rs232/doc.txt

Library: RS-232
Author:  Teunis van Beelen
Url:     http://www.teuniz.net/RS-232/
E-mail:  teuniz@protonmail.com
License: GPLv3

Last revision: May 31, 2019



int RS232_OpenComport(int comport_number, int baudrate, const char * mode, int flowctrl)

  Opens the comport, comportnumber starts with 0 (see the list of numbers).
  Baudrate is expressed in baud per second i.e 115200 (see the list of possible baudrates).
  Mode is a string in the form of "8N1", "7E2", etc.
  8N1 means eight databits, no parity, one stopbit. If in doubt, use 8N1 (see the list of possible modes).
  If flowctrl is set to 0, no flow control is used.
  If flowctrl is set to 1, hardware flow control is enabled using the RTS/CTS lines.
  Returns 1 in case of an error.
  In case the comport is already opened (by another process),
  it will not open the port but raise an error instead.

int RS232_PollComport(int comport_number, unsigned char *buf, int size)

  Gets characters from the serial port (if any). Buf is a pointer to a buffer
  and size the size of the buffer in bytes.
  Returns the amount of received characters into the buffer. This can be less than size or zero!
  It does not block or wait, it returns immediately, no matter if any characters have been received or not.
  After succesfully opening the COM-port, connect this function to a timer.
  The timer should have an interval of approx. 20 to 100 milliSeconds.
  Do not forget to stop the timer before closing the COM-port.
  Allways check the return value! The return value tells you how many bytes
  are actually received and present in your buffer!

int RS232_SendByte(int comport_number, unsigned char byte)

  Sends a byte via the serial port. Returns 1 in case of an error.

int RS232_SendBuf(int comport_number, unsigned char *buf, int size)

  Sends multiple bytes via the serial port. Buf is a pointer to a buffer
  and size the size of the buffer in bytes.
  Returns -1 in case of an error, otherwise it returns the amount of bytes sent.
  This function blocks (it returns after all the bytes have been processed).

void RS232_CloseComport(int comport_number)

  Closes the serial port.

void RS232_cputs(int comport_number, const char *text)

  Sends a string via the serial port. String must be null-terminated.

int RS232_GetPortnr(const char *devname)

  Returns the comport number based on the device name e.g. "ttyS0" or "COM1".
  (Doesn't mean the device actually exists!)
  Returns -1 when not found.


The following functions are normally not needed but can be used to set or check the status of the control-lines:
================================================================================================================

void RS232_enableDTR(int comport_number)

  Sets the DTR line high (active state).

void RS232_disableDTR(int comport_number)

  Sets the DTR line low (non active state).

void RS232_enableRTS(int comport_number)

  Sets the RTS line high (active state). Do not use this function if hardware flow control is enabled!

void RS232_disableRTS(int comport_number) Do not use this function if hardware flow control is enabled!

  Sets the RTS line low (non active state).

int RS232_IsRINGEnabled(int comport_number)

  Checks the status of the RING-pin. Returns 1 when the the RING line is high (active state), otherwise 0.

int RS232_IsDSREnabled(int comport_number)

  Checks the status of the DSR-pin. Returns 1 when the the DSR line is high (active state), otherwise 0.

int RS232_IsCTSEnabled(int comport_number)

  Checks the status of the CTS-pin. Returns 1 when the the CTS line is high (active state), otherwise 0.

int RS232_IsDCDEnabled(int comport_number)

  Checks the status of the DCD-pin. Returns 1 when the the DCD line is high (active state), otherwise 0.


The following functions are normally not needed but can be used to empty the rx/tx buffers:
===========================================================================================

("discards data written to the serial port but not transmitted, or data received but not read")

void RS232_flushRX(int comport_number)

  Flushes data received but not read.

void RS232_flushTX(int comport_number)

  Flushes data written but not transmitted.

void RS232_flushRXTX(int comport_number)

  Flushes both data received but not read, and data written but not transmitted.



Notes:

You don't need to call RS232_PollComport() when you only want to send characters.
Sending and receiving do not influence eachother.

The os (kernel) has an internal buffer of 4096 bytes (for traditional onboard serial ports).
USB/Serial-converter drivers use much bigger buffers (multiples of 4096).
If this buffer is full and a new character arrives on the serial port,
the oldest character in the buffer will be overwritten and thus will be lost.

After a successfull call to RS232_OpenComport(), the os will start to buffer incoming characters.

tip: To get access to the serial port on Linux, you need to be a member of the group "dialout".

Note: Traditional (on-board) UART's usually have a speed limit of max. 115200 baud.
            Special cards and USB to Serial converters can usually be set to higher baudrates.


List of comport numbers, possible baudrates and modes:

    Linux     windows
0   ttyS0     COM1
1   ttyS1     COM2
2   ttyS2     COM3
3   ttyS3     COM4
4   ttyS4     COM5
5   ttyS5     COM6
6   ttyS6     COM7
7   ttyS7     COM8
8   ttyS8     COM9
9   ttyS9     COM10
10  ttyS10    COM11
11  ttyS11    COM12
12  ttyS12    COM13
13  ttyS13    COM14
14  ttyS14    COM15
15  ttyS15    COM16
16  ttyUSB0   COM17
17  ttyUSB1   COM18
18  ttyUSB2   COM19
19  ttyUSB3   COM20
20  ttyUSB4   COM21
21  ttyUSB5   COM22
22  ttyAMA0   COM23
23  ttyAMA1   COM24
24  ttyACM0   COM25
25  ttyACM1   COM26
26  rfcomm0   COM27
27  rfcomm1   COM28
28  ircomm0   COM29
29  ircomm1   COM30
30  cuau0     COM31
31  cuau1     COM32
32  cuau2     n.a.
33  cuau3     n.a.
34  cuaU0     n.a.
35  cuaU1     n.a.
36  cuaU2     n.a.
37  cuaU3     n.a.

Linux     windows
50        n.a.
75        n.a.
110       110
134       n.a.
150       n.a.
200       n.a.
300       300
600       600
1200      1200
1800      n.a.
2400      2400
4800      4800
9600      9600
19200     19200
38400     38400
57600     57600
115200    115200
230400    128000
460800    256000
500000    500000
576000    n.a.
921600    921600
1000000   1000000
1152000   n.a.
1500000   1500000
2000000   2000000
2500000   n.a.
3000000   3000000
3500000   n.a.
4000000   n.a.

Mode
8N1
8O1
8E1
8N2
8O2
8E2
7N1
7O1
7E1
7N2
7O2
7E2
6N1
6O1
6E1
6N2
6O2
6E2
5N1
5O1
5E1
5N2
5O2
5E2