Add example of sending and receiving data.

[libserialport.git] / examples / send_receive.c

diff --git a/examples/send_receive.c b/examples/send_receive.c
new file mode 100644 (file)
index 0000000..e1aabf0
--- /dev/null
+++ b/examples/send_receive.c
@@ -0,0 +1,136 @@
+#include <libserialport.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+/* Example of how to send and receive data.
+ *
+ * This example file is released to the public domain. */
+
+/* Helper function for error handling. */
+int check(enum sp_return result);
+
+int main(int argc, char **argv)
+{
+       /* This example can be used with one or two ports. With one port, it
+        * will send data and try to receive it on the same port. This can be
+        * done by connecting a single wire between the TX and RX pins of the
+        * port.
+        *
+        * Alternatively it can be used with two serial ports connected to each
+        * other, so that data can be sent on one and received on the other.
+        * This can be done with two ports with TX/RX cross-connected, e.g. by
+        * a "null modem" cable, or with a pair of interconnected virtual ports,
+        * such as those created by com0com on Windows or tty0tty on Linux. */
+
+       /* Get the port names from the command line. */
+       if (argc < 2 || argc > 3) {
+               printf("Usage: %s <port 1> [<port 2>]\n", argv[0]);
+               return -1;
+       }
+       int num_ports = argc - 1;
+       char **port_names = argv + 1;
+
+       /* The ports we will use. */
+       struct sp_port *ports[2];
+
+       /* Open and configure each port. */
+       for (int i = 0; i < num_ports; i++) {
+               printf("Looking for port %s.\n", port_names[i]);
+               check(sp_get_port_by_name(port_names[i], &ports[i]));
+
+               printf("Opening port.\n");
+               check(sp_open(ports[i], SP_MODE_READ_WRITE));
+
+               printf("Setting port to 9600 8N1, no flow control.\n");
+               check(sp_set_baudrate(ports[i], 9600));
+               check(sp_set_bits(ports[i], 8));
+               check(sp_set_parity(ports[i], SP_PARITY_NONE));
+               check(sp_set_stopbits(ports[i], 1));
+               check(sp_set_flowcontrol(ports[i], SP_FLOWCONTROL_NONE));
+       }
+
+       /* Now send some data on each port and receive it back. */
+       for (int tx = 0; tx < num_ports; tx++) {
+               /* Get the ports to send and receive on. */
+               int rx = num_ports == 1 ? 0 : ((tx == 0) ? 1 : 0);
+               struct sp_port *tx_port = ports[tx];
+               struct sp_port *rx_port = ports[rx];
+
+               /* The data we will send. */
+               char *data = "Hello!";
+               int size = strlen(data);
+
+               /* We'll allow a 1 second timeout for send and receive. */
+               unsigned int timeout = 1000;
+
+               /* On success, sp_blocking_write() and sp_blocking_read()
+                * return the number of bytes sent/received before the
+                * timeout expired. We'll store that result here. */
+               int result;
+
+               /* Send data. */
+               printf("Sending '%s' (%d bytes) on port %s.\n",
+                               data, size, sp_get_port_name(tx_port));
+               result = check(sp_blocking_write(tx_port, data, size, timeout));
+
+               /* Check whether we sent all of the data. */
+               if (result == size)
+                       printf("Sent %d bytes successfully.\n", size);
+               else
+                       printf("Timed out, %d/%d bytes sent.\n", result, size);
+
+               /* Allocate a buffer to receive data. */
+               char buf[size + 1];
+
+               /* Try to receive the data on the other port. */
+               printf("Receiving %d bytes on port %s.\n",
+                               size, sp_get_port_name(rx_port));
+               check(sp_blocking_read(rx_port, buf, size, timeout));
+
+               /* Check whether we received the number of bytes we wanted. */
+               if (result == size)
+                       printf("Received %d bytes successfully.\n", size);
+               else
+                       printf("Timed out, %d/%d bytes received.\n", result, size);
+
+               /* Check if we received the same data we sent. */
+               buf[result] = '\0';
+               printf("Received '%s'.\n", buf);
+       }
+
+       /* Close ports and free resources. */
+       for (int i = 0; i < num_ports; i++) {
+               check(sp_close(ports[i]));
+               sp_free_port(ports[i]);
+       }
+
+       return 0;
+}
+
+/* Helper function for error handling. */
+int check(enum sp_return result)
+{
+       /* For this example we'll just exit on any error by calling abort(). */
+       char *error_message;
+
+       switch (result) {
+       case SP_ERR_ARG:
+               printf("Error: Invalid argument.\n");
+               abort();
+       case SP_ERR_FAIL:
+               error_message = sp_last_error_message();
+               printf("Error: Failed: %s\n", error_message);
+               sp_free_error_message(error_message);
+               abort();
+       case SP_ERR_SUPP:
+               printf("Error: Not supported.\n");
+               abort();
+       case SP_ERR_MEM:
+               printf("Error: Couldn't allocate memory.\n");
+               abort();
+       case SP_OK:
+       default:
+               return result;
+       }
+}