Jan Jongboom
Serial#Find method for Arduino, implemented in Mbed
Adoption of https://www.arduino.cc/en/Serial/Find, implemented without use of interrupts or buffers. Note that it keeps the thread busy, so if you're running this in the background, better use Serial#attach with a buffer.
Revision 0:6228e490f311, committed 2017-11-10
- Comitter:
- Jan Jongboom
- Date:
- Fri Nov 10 21:11:04 2017 +0900
- Commit message:
- Initial commit, tested on K64F with ESP8266 module
Changed in this revision
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/.hgignore Fri Nov 10 21:11:04 2017 +0900 @@ -0,0 +1,5 @@ +BUILD/ +mbed-os/ +.mbed +mbed_settings.* +.git/
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp Fri Nov 10 21:11:04 2017 +0900
@@ -0,0 +1,76 @@
+#include "mbed.h"
+
+Serial pc(USBTX, USBRX);
+
+/**
+ * Arduino's Serial#Find method (https://www.arduino.cc/en/Serial/Find) adopted to Mbed OS.
+ * Does not allocate buffers inside.
+ *
+ * Example (finding the string 'ready' in a stream):
+ * Serial uart(D1, D0);
+ * uart.baud(115200);
+ *
+ * bool found = serial_find(&uart, "ready", 10);
+ * printf("Found it? %d\n", found)
+ *
+ * @param serial Pointer to an initialized UART Serial object
+ * @param str_to_find String to find in the UART stream
+ * @param timeout_s Timeout in seconds
+ * @returns True if found, false if timed out
+ */
+static bool serial_find(Serial *serial, const char *str_to_find, uint32_t timeout_s) {
+ // Use RTC (instead of interrupt) for timeout detection
+ time_t curr = time(NULL);
+
+ bool is_partial_match = false;
+ uint16_t match_ix = 0;
+ size_t str_to_find_len = strlen(str_to_find);
+
+ while (1) {
+ // timeout detection
+ if (time(NULL) - curr > timeout_s) return false;
+
+ while (serial->readable()) {
+ // also do timeout detection here...
+ if (time(NULL) - curr > timeout_s) return false;
+
+ char c = serial->getc();
+
+ if (!is_partial_match) {
+ // Find the first character in the stream
+ if (c == str_to_find[0]) {
+ if (str_to_find_len == 1) return true;
+
+ match_ix = 1;
+ is_partial_match = true;
+ }
+ continue;
+ }
+
+ // is_partial_match is correct, check remaining characters
+ if (c == str_to_find[match_ix]) {
+ if (str_to_find_len == match_ix + 1) return true;
+
+ match_ix++;
+ }
+ else {
+ // not a match anymore, continue
+ is_partial_match = false;
+ }
+ }
+ }
+
+ return false;
+}
+
+int main() {
+ pc.baud(115200);
+ pc.printf("Hello world\n");
+
+ // set up connection over UART, e.g. to ESP8266 WiFi module...
+ Serial uart(D1, D0);
+ uart.baud(115200);
+
+ bool found = serial_find(&uart, "ready", 10);
+ printf("Found it? %d\n", found);
+}
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mbed-os.lib Fri Nov 10 21:11:04 2017 +0900 @@ -0,0 +1,1 @@ +https://github.com/ARMmbed/mbed-os/#78474a5129e18e136cc7e872adbaa5b74fbb8f6a