UART write example (#53)

* Rename test functions

* rewrite furi API, segfault

* make fixes in FURI, log through FURI

* add uart write example blank

* implement fuprintf instead of fopencookie

* add gif, blank page

* UART write example description

Co-authored-by: Vadim Kaushan <admin@disasm.info>

applications/examples/uart_write.c

@@ -0,0 +1,33 @@
+#include "flipper.h"
+#include <string.h>
+#include "log.h"
+
+void application_uart_write(void* p) {
+    // Red led for showing progress
+    GpioPin led = {.pin = GPIO_PIN_8, .port = GPIOA};
+    pinMode(led, GpioModeOpenDrain);
+
+    // get_default_log open "tty" record
+    FuriRecordSubscriber* log = get_default_log();
+
+    // create buffer
+    const char test_string[] = "test\n";
+    furi_write(log, test_string, strlen(test_string));
+
+    // for example, create counter and show its value
+    uint8_t counter = 0;
+
+    while(1) {
+        // continously write it to UART
+        fuprintf(log, "counter: %d\n", counter);
+        counter++;
+
+        // flash at every send
+        digitalWrite(led, LOW);
+        delay(50);
+        digitalWrite(led, HIGH);
+
+        // delay with overall perion of 1s
+        delay(950);
+    }
+}