docs: add alternative for bin2hex and add link for the bug

README.md

@@ -16,6 +16,17 @@ gst-launch-1.0 -q uridecodebin uri=file:///path/to/audio-file ! audioconvert ! \
   perl ~/bin/bin2hex.pl /tmp/snd 1 | sed -e 's/bin_data|wave_data/' >/tmp/wave_data.h
 ```
 
+An alternative for bin2hex.pl would be:
+
+```Shell
+size=$(stat -c "%s" /tmp/snd); \
+(
+  echo "static uint8_t wave_data[] = { /* ${size} */";
+  hexdump -v -e '15/1 "0x%02X," "\n"' /tmp/snd | sed -e 's/0x  ,//g';
+  echo "};"
+) >wave_data.h
+```
+
 gstreamer is included with most linux distros and I found the bin2hex.pl at
 http://www.chami.com/tips/delphi/052098D.html
 

firmware/PhotonWaveOut.cpp

@@ -91,4 +91,9 @@ void WaveOut::playback_handler(void) {
       pinResetFast(current->pin_p);
     }
   }
+  /* once DAC bug in 0.4.7 (https://github.com/spark/firmware/issues/671) is
+   * fixed we could do this with one pin instead:
+  pinMode(audio, OUTPUT);
+  analogWrite(audio, (v<<4));
+  */
 }