fix polarity of DE, osci image of working example

pyserialext/writec.c

@@ -9,17 +9,17 @@ const uint8_t DE_PIN = 0;
 int init() {
   wiringPiSetup();
   pinMode(DE_PIN, OUTPUT);
-  digitalWrite(DE_PIN, HIGH);
+  digitalWrite(DE_PIN, LOW);
 }
 
 ssize_t writec(int fd, char *buf, size_t count) {
-  digitalWrite(DE_PIN, LOW);
+  digitalWrite(DE_PIN, HIGH);
   ssize_t r = write(fd, buf, count);
   uint8_t lsr;
   do {
     int r = ioctl(fd, TIOCSERGETLSR, &lsr);
   } while (!(lsr & TIOCSER_TEMT));
-  digitalWrite(DE_PIN, HIGH);
+  digitalWrite(DE_PIN, LOW);
 
   return r;
 }