Difference between revisions of "Xenomai RTSerial"

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<!-- /*********************************************************************************************************/ -->
 
<!-- /*********************************************************************************************************/ -->
 
{{:Templateimpl:using | initials=MW | title=Xenomai RTSerial | desc=Xenomai RTSerial | project=OE 5.0 }}
 
{{:Templateimpl:using | initials=MW | title=Xenomai RTSerial | desc=Xenomai RTSerial | project=OE 5.0 }}
Given the RTDM serial port driver exist and is loaded for the target on hand, it will provide a device nodes at /dev/rtdm/rtserX where X is replaced by the number of the port.
+
Given the RTDM serial port driver exists and is loaded for the target on hand, it will provide device nodes at <code>/dev/rtdm/rtserX</code> where X is replaced by the number of each port.
This device node is then accessed to configured and communicate using the underlying port. The following sections with outline loading the driver, configuring the port, and performing basic serial transactions.
+
The device nodes are then accessed to configured and communicate the underlying serial ports. The following subsections will outline loading the driver, configuring the port, and performing basic serial transactions.
  
 
=== Loading the driver ===
 
=== Loading the driver ===
Typically there will be a Linux kernel driver associated with the port. If desired device is associated with a Linux driver the driver must be unloaded or the device must be unbound from the driver. Below are examples of loading the RTDM driver for some supported targets.
+
Typically there will be a Linux kernel driver associated with the serial port by default. If the desired device is associated with a Linux driver the driver must be unloaded or the device must be unbound from the driver. Below are examples of loading the RTDM driver for some supported targets.
  
 
==== x86 16550A ====
 
==== x86 16550A ====
Line 43: Line 43:
 
[  528.025034] rtser0 on IMX UART0: membase=0xc0c10000 irq=58 uartclk=80000000
 
[  528.025034] rtser0 on IMX UART0: membase=0xc0c10000 irq=58 uartclk=80000000
 
[  528.025700] rtser1 on IMX UART1: membase=0xc0c18000 irq=59 uartclk=80000000
 
[  528.025700] rtser1 on IMX UART1: membase=0xc0c18000 irq=59 uartclk=80000000
[  528.026096] rtser2 on IMX UART2: membase=0xc0c20000 irq=60 uartclk=80000000
+
</syntaxhighlight>
 +
 
 +
==== AT91 atmel_rt_serial ====
 +
<syntaxhighlight lang="console">
 +
COMA
 +
root@som9x25:~# echo f8040000.serial > /sys/bus/platform/drivers/atmel_usart/unbind
 +
COMD
 +
root@som9x25:~# echo f8024000.serial > /sys/bus/platform/drivers/atmel_usart/unbind
 +
root@som9x25:~# modprobe atmel_rt_serial
 +
rtser0 on ATMEL UART-1: membase=0xc8dd0000 irq=29 uartclk=133333333
 +
rtser1 on ATMEL UART-1: membase=0xc8dd2000 irq=30 uartclk=133333333
 
</syntaxhighlight>
 
</syntaxhighlight>
  
 
=== Configuring the serial port ===
 
=== Configuring the serial port ===
 
<syntaxhighlight lang="c">
 
<syntaxhighlight lang="c">
 
+
static const struct rtser_config my_config = {
static const struct rtser_config my_config = { .config_mask      = 0xFFFF, .baud_rate        = 115200, .parity            = RTSER_DEF_PARITY, .data_bits        = RTSER_DEF_BITS, .stop_bits        = RTSER_DEF_STOPB, .handshake        = RTSER_DEF_HAND, .fifo_depth        = RTSER_DEF_FIFO_DEPTH, .rx_timeout        = RTSER_DEF_TIMEOUT, .tx_timeout        = RTSER_DEF_TIMEOUT, .event_timeout    = 1000000000, /* 1 s */ .timestamp_history = RTSER_RX_TIMESTAMP_HISTORY, .event_mask        = RTSER_EVENT_RXPEND,};</syntaxhighlight>
+
.config_mask      = 0xFFFF,
<syntaxhighlight lang="c">
+
.baud_rate        = 115200,
 +
.parity            = RTSER_DEF_PARITY,
 +
.data_bits        = RTSER_DEF_BITS,
 +
.stop_bits        = RTSER_DEF_STOPB,
 +
.handshake        = RTSER_DEF_HAND,
 +
.fifo_depth        = RTSER_DEF_FIFO_DEPTH,
 +
.rx_timeout        = RTSER_DEF_TIMEOUT,
 +
.tx_timeout        = RTSER_DEF_TIMEOUT,
 +
.event_timeout    = 1000000000, /* 1 s */
 +
.timestamp_history = RTSER_RX_TIMESTAMP_HISTORY,
 +
.event_mask        = RTSER_EVENT_RXPEND,
 +
};
 +
...
 
int fd;
 
int fd;
 +
int err;
 +
...
 +
fd = open("/dev/rtdm/rtser0", 0);
  
fd = open("/dev/rtdm/rtser0", 0);
+
if (fd < 0) {
 +
printf("open error %s\n", strerror(errno));
 +
return -errno;
 +
}
 +
...
 +
err = ioctl(fd, RTSER_RTIOC_SET_CONFIG, &my_config);
 +
if (err) {
 +
printf("ioctl error %s\n", strerror(errno));
 +
goto error;
 +
}
 +
...
 +
</syntaxhighlight>
 +
=== Performing serial transactions ===
 +
Performing serial transactions is as simple as reading and write to the rtser file descriptor.
  
if (fd < 0) { printf("can't open rtser0, %s\n",       strerror(-errno)); return -errno; }
+
Sending the contents of a buffer over the serial port:
err = ioctl(fd, RTSER_RTIOC_SET_CONFIG, &my_config); if (err) { printf("error while ioctl, %s\n",       strerror(-errno)); }</syntaxhighlight>
+
<syntaxhighlight lang="c">
 +
ret = write(fd, buffer, sizeof(buffer));
 +
</syntaxhighlight>
  
 +
Receiving serial port input data into buffer:
 +
<syntaxhighlight lang="c">
 +
ret = read(fd, buffer, sizeof(buffer));
 +
</syntaxhighlight>
  
=== Performing serial transactions ===
+
When reading from the serial it is useful to wait for an event to occur before reading:
 +
<syntaxhighlight lang="c">
 +
err = ioctl(read_fd, RTSER_RTIOC_WAIT_EVENT, &rx_event);
 +
if (err) {
 +
printf("ioctl error on RTSER_RTIOC_WAIT_EVENT %s\n",
 +
      strerror(errno));
 +
}
 +
</syntaxhighlight>
  
 
<!-- /*********************************************************************************************************/ -->
 
<!-- /*********************************************************************************************************/ -->
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<!-- /*********************************************************************************************************/ -->
 
<!-- /*********************************************************************************************************/ -->
 
{{:Templateimpl:examples | initials=MW | title=Xenomai RTSerial | desc=Xenomai RTSerial | project=OE 5.0 }}
 
{{:Templateimpl:examples | initials=MW | title=Xenomai RTSerial | desc=Xenomai RTSerial | project=OE 5.0 }}
Xenomai provides an example called cross-link which provides an easy way to test serial ports. Essentially the demo send data from one serial port and receives it on another. To run the demo make sure the RTDM driver is load and connect the first two port via a NULL modem cable.
+
Xenomai provides an example called cross-link which provides an easy way to test serial ports. Essentially the demo sends data from one serial port and receives it on another. To run the demo make sure the RTDM driver is loaded and connect the first two ports via a NULL modem cable.
 
<syntaxhighlight lang="console">
 
<syntaxhighlight lang="console">
 
root@somimx6-xenomai:~# /usr/demo/cross-link
 
root@somimx6-xenomai:~# /usr/demo/cross-link
Line 86: Line 137:
 
</syntaxhighlight>
 
</syntaxhighlight>
  
<!-- /*********************************************************************************************************/ -->
+
== External Links ==
<!-- /******************************************    Conclusion      ******************************************/ -->
+
* https://xenomai.org/documentation/xenomai-3/html/xeno3prm/group__rtdm__serial.html
<!-- /*********************************************************************************************************/ -->
+
* https://xenomai.org/documentation/xenomai-3/html/xeno3prm/rtdm_2uapi_2serial_8h.html
{{:Templateimpl:conclusion | initials=MW | title=Xenomai RTSerial | desc=Xenomai RTSerial | project=OE 5.0 }}
+
* https://xenomai.org/documentation/xenomai-3/html/xeno3prm/cross-link_8c-example.html
 
 
<!-- /*********************************************************************************************************/ -->
 
<!-- /******************************************  More Information  *****************************************/ -->
 
<!-- /*********************************************************************************************************/ -->
 
{{:Templateimpl:moreinfo | initials=MW | title=Xenomai RTSerial | desc=Xenomai RTSerial | project=OE 5.0 }}
 
*
 
 
 
{{:Templateimpl:whatnext | initials=MW | title=Xenomai RTSerial | desc=Xenomai RTSerial | project=OE 5.0 }}
 
*
 

Latest revision as of 17:16, 6 February 2018

TODO: {{#todo: NotStarted (03.03.2016-13:01->MW+)|Michael Welling|OE 5.0,MW,NotStarted}}

General Information

Xenomai provides a RTDM profile for serial device drivers enabling real-time UART serial communication. The RTDM serial driver provides the necessary user-space API to perform serial port configuration and communication. The following sections will outline the use of the user-space interface and provide basic examples.

Xenomai RTSerial

Given the RTDM serial port driver exists and is loaded for the target on hand, it will provide device nodes at /dev/rtdm/rtserX where X is replaced by the number of each port. The device nodes are then accessed to configured and communicate the underlying serial ports. The following subsections will outline loading the driver, configuring the port, and performing basic serial transactions.

Loading the driver

Typically there will be a Linux kernel driver associated with the serial port by default. If the desired device is associated with a Linux driver the driver must be unloaded or the device must be unbound from the driver. Below are examples of loading the RTDM driver for some supported targets.

x86 16550A

iMX6 rt_imx_uart

root@somimx6-xenomai:~# echo 2020000.serial > /sys/bus/platform/drivers/imx-uart/unbind
root@somimx6-xenomai:~# echo 21e8000.serial > /sys/bus/platform/drivers/imx-uart/unbind
root@somimx6-xenomai:~# modprobe xeno_imx_uart
root@somimx6-xenomai:~# dmesg | tail
.
.
[  462.425158] console [ttymxc1] disabled
[  528.025034] rtser0 on IMX UART0: membase=0xc0c10000 irq=58 uartclk=80000000
[  528.025700] rtser1 on IMX UART1: membase=0xc0c18000 irq=59 uartclk=80000000

AT91 atmel_rt_serial

COMA
root@som9x25:~# echo f8040000.serial > /sys/bus/platform/drivers/atmel_usart/unbind
COMD
root@som9x25:~# echo f8024000.serial > /sys/bus/platform/drivers/atmel_usart/unbind
root@som9x25:~# modprobe atmel_rt_serial
rtser0 on ATMEL UART-1: membase=0xc8dd0000 irq=29 uartclk=133333333
rtser1 on ATMEL UART-1: membase=0xc8dd2000 irq=30 uartclk=133333333

Configuring the serial port

static const struct rtser_config my_config = {
	.config_mask       = 0xFFFF,
	.baud_rate         = 115200,
	.parity            = RTSER_DEF_PARITY,
	.data_bits         = RTSER_DEF_BITS,
	.stop_bits         = RTSER_DEF_STOPB,
	.handshake         = RTSER_DEF_HAND,
	.fifo_depth        = RTSER_DEF_FIFO_DEPTH,
	.rx_timeout        = RTSER_DEF_TIMEOUT,
	.tx_timeout        = RTSER_DEF_TIMEOUT,
	.event_timeout     = 1000000000, /* 1 s */
	.timestamp_history = RTSER_RX_TIMESTAMP_HISTORY,
	.event_mask        = RTSER_EVENT_RXPEND,
};
...
	int fd;
	int err;
...
	fd = open("/dev/rtdm/rtser0", 0);

	if (fd < 0) {
		printf("open error %s\n", strerror(errno));
		return -errno;
	}
...
	err = ioctl(fd, RTSER_RTIOC_SET_CONFIG, &my_config);
	if (err) {
		printf("ioctl error %s\n", strerror(errno));
		goto error;
	}
...

Performing serial transactions

Performing serial transactions is as simple as reading and write to the rtser file descriptor.

Sending the contents of a buffer over the serial port:

	ret = write(fd, buffer, sizeof(buffer));

Receiving serial port input data into buffer:

	ret = read(fd, buffer, sizeof(buffer));

When reading from the serial it is useful to wait for an event to occur before reading:

	err = ioctl(read_fd, RTSER_RTIOC_WAIT_EVENT, &rx_event);
	if (err) {
		printf("ioctl error on RTSER_RTIOC_WAIT_EVENT %s\n",
		       strerror(errno));
	}

Examples

Xenomai provides an example called cross-link which provides an easy way to test serial ports. Essentially the demo sends data from one serial port and receives it on another. To run the demo make sure the RTDM driver is loaded and connect the first two ports via a NULL modem cable.

root@somimx6-xenomai:~# /usr/demo/cross-link
main : write-file opened
main : write-config written
main : read-file openedmain : read-config written
main : write-task createdmain : read-task created
main : starting write-task
main : starting read-task
 Nr |   write->irq    |    irq->read    |   write->read   |
-----------------------------------------------------------
  0 |18446744041591572624 |     32118717325 |          738333
  1 |18446744041591563290 |     32118715326 |          727000
  2 |18446744041591563957 |     32118716326 |          728667
  3 |18446744041591561291 |     32118714658 |          724333
  4 |18446744041591562624 |     32118715992 |          727000
  5 |18446744041591560290 |     32118715326 |          724000
.
.

External Links