main.cpp

00001 #include "mbed.h"
00002 
00003 Serial pc(USBTX, USBRX);
00004 
00005 /**
00006  * Arduino's Serial#Find method (https://www.arduino.cc/en/Serial/Find) adopted to Mbed OS.
00007  * Does not allocate buffers inside.
00008  *
00009  * Example (finding the string 'ready' in a stream):
00010  *      Serial uart(D1, D0);
00011  *      uart.baud(115200);
00012  *
00013  *      bool found = serial_find(&uart, "ready", 10);
00014  *      printf("Found it? %d\n", found)
00015  *
00016  * @param serial Pointer to an initialized UART Serial object
00017  * @param str_to_find String to find in the UART stream
00018  * @param timeout_s Timeout in seconds
00019  * @returns True if found, false if timed out
00020  */
00021 static bool serial_find(Serial *serial, const char *str_to_find, uint32_t timeout_s) {
00022     // Use RTC (instead of interrupt) for timeout detection
00023     time_t curr = time(NULL);
00024 
00025     bool is_partial_match = false;
00026     uint16_t match_ix = 0;
00027     size_t str_to_find_len = strlen(str_to_find);
00028 
00029     while (1) {
00030         // timeout detection
00031         if (time(NULL) - curr > timeout_s) return false;
00032 
00033         while (serial->readable()) {
00034             // also do timeout detection here...
00035             if (time(NULL) - curr > timeout_s) return false;
00036 
00037             char c = serial->getc();
00038 
00039             if (!is_partial_match) {
00040                 // Find the first character in the stream
00041                 if (c == str_to_find[0]) {
00042                     if (str_to_find_len == 1) return true;
00043 
00044                     match_ix = 1;
00045                     is_partial_match = true;
00046                 }
00047                 continue;
00048             }
00049 
00050             // is_partial_match is correct, check remaining characters
00051             if (c == str_to_find[match_ix]) {
00052                 if (str_to_find_len == match_ix + 1) return true;
00053 
00054                 match_ix++;
00055             }
00056             else {
00057                 // not a match anymore, continue
00058                 is_partial_match = false;
00059             }
00060         }
00061     }
00062 
00063     return false;
00064 }
00065 
00066 int main() {
00067     pc.baud(115200);
00068     pc.printf("Hello world\n");
00069 
00070     // set up connection over UART, e.g. to ESP8266 WiFi module...
00071     Serial uart(D1, D0);
00072     uart.baud(115200);
00073 
00074     bool found = serial_find(&uart, "ready", 10);
00075     printf("Found it? %d\n", found);
00076 }