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Revision 1.3 2004/11/24 16:35:56 haraldkipp Configurable floating point support
Revision 1.2 2004/09/10 10:33:28 haraldkipp Temporarly removed non-configurable FP support
Revision 1.1 2003/08/05 18:59:52 haraldkipp Release 3.3 update
Revision 1.3 2003/02/04 18:19:41 harald Version 3 released
Revision 1.2 2003/02/04 16:24:38 harald Adapted to version 3
Revision 1.1 2002/08/09 12:44:10 harald Renamed for make rules
Revision 1.5 2002/06/12 11:00:10 harald *** empty log message ***
Revision 1.4 2002/06/04 19:13:21 harald *** empty log message ***
Revision 1.3 2002/05/08 16:02:34 harald First Imagecraft compilation
Revision 1.2 2001/08/10 18:20:41 harald GCC version 3 update
Revision 1.1 2001/06/28 18:43:13 harald Preview release
This sample demonstrates the usage of the ATmega on-chip UART. Note, that we don't do any error checking, because without this UART we can't tell the user our problem.
We use floating points. Make sure to link with nutlibcrtf.
00001 00083 #include <cfg/crt.h> /* Floating point configuration. */ 00084 00085 #include <string.h> 00086 #include <stdio.h> 00087 #include <io.h> 00088 00089 #include <dev/board.h> 00090 #include <sys/timer.h> 00091 00092 static char *banner = "\nNut/OS UART Sample\n"; 00093 static prog_char presskey_P[] = "Press any key..."; 00094 static prog_char pgm_ptr[] = "\nHello stranger!\n"; 00095 00096 static char inbuf[128]; 00097 00098 /* 00099 * UART sample. 00100 * 00101 * Some functions do not work with ICCAVR. 00102 */ 00103 int main(void) 00104 { 00105 int got; 00106 int i; 00107 char *cp; 00108 u_long baud = 115200; 00109 FILE *uart; 00110 #ifdef STDIO_FLOATING_POINT 00111 float dval = 0.0; 00112 #endif 00113 00114 /* 00115 * Each device must be registered. We do this by referencing the 00116 * device structure of the driver. The advantage is, that only 00117 * those device drivers are included in our flash code, which we 00118 * really need. 00119 * 00120 * The uart0 device is the first one on the ATmega chip. So it 00121 * has no configurable base address or interrupt and we set both 00122 * parameters to zero. 00123 */ 00124 NutRegisterDevice(&DEV_UART, 0, 0); 00125 00126 /* 00127 * Now, as the device is registered, we can open it. The fopen() 00128 * function returns a pointer to a FILE structure, which we use 00129 * for subsequent reading and writing. 00130 */ 00131 uart = fopen(DEV_UART_NAME, "r+"); 00132 00133 /* 00134 * Before doing the first read or write, we set the baudrate. 00135 * This low level function doesn't know about FILE structures 00136 * and we use _fileno() to get the low level file descriptor 00137 * of the stream. 00138 * 00139 * The short sleep allows the UART to settle after the baudrate 00140 * change. 00141 */ 00142 _ioctl(_fileno(uart), UART_SETSPEED, &baud); 00143 00144 /* 00145 * Stream devices can use low level read and write functions. 00146 * Writing program space data is supported too. 00147 */ 00148 _write(_fileno(uart), banner, strlen(banner)); 00149 { 00150 _write_P(_fileno(uart), presskey_P, sizeof(presskey_P)); 00151 } 00152 00153 /* 00154 * Stream devices do buffered I/O. That means, nothing will be 00155 * passed to the hardware device until either the output buffer 00156 * is full or we do a flush. With stream I/O we typically use 00157 * fflush(), but low level writing a null pointer will also flush 00158 * the output buffer. 00159 */ 00160 _write(_fileno(uart), 0, 0); 00161 00162 /* 00163 * The low level function read() will grab all available bytes 00164 * from the input buffer. If the buffer is empty, the call will 00165 * block until something is available for reading. 00166 */ 00167 got = _read(_fileno(uart), inbuf, sizeof(inbuf)); 00168 _write(_fileno(uart), inbuf, got); 00169 00170 /* 00171 * Nut/OS never expects a thread to return. So we enter an 00172 * endless loop here. 00173 */ 00174 for (i = 0;; i++) { 00175 /* 00176 * A bit more advanced input routine is able to read a string 00177 * up to and including the first newline character or until a 00178 * specified maximum number of characters, whichever comes first. 00179 */ 00180 fputs("\nEnter your name: ", uart); 00181 fflush(uart); 00182 fgets(inbuf, sizeof(inbuf), uart); 00183 00184 /* 00185 * Chop off trailing linefeed. 00186 */ 00187 cp = strchr(inbuf, '\n'); 00188 if (cp) 00189 *cp = 0; 00190 00191 /* 00192 * Streams support formatted output as well as printing strings 00193 * from program space. 00194 */ 00195 if (inbuf[0]) 00196 fprintf(uart, "\nHello %s!\n", inbuf); 00197 else { 00198 fputs_P(pgm_ptr, uart); 00199 } 00200 00201 /* 00202 * Just to demonstrate formatted floating point output. 00203 * In order to use this, we need to link the application 00204 * with nutcrtf instead of nutcrt for pure integer. 00205 */ 00206 #ifdef STDIO_FLOATING_POINT 00207 dval += 1.0125; 00208 fprintf(uart, "FP %f\n", dval); 00209 #endif 00210 } 00211 }