Restored "GPIO sidetone" since this *may* be useful.

diff --git a/gpio.c b/gpio.c
index 7d08b35bc377e7e7bb9324d0c8e61b364c76939f..a7d3c9a9a435f9a71ab54d3625a2d4ecae1d5670 100644 (file)
--- a/gpio.c
+++ b/gpio.c
@@ -2353,3 +2353,18 @@ static gpointer rotary_encoder_thread(gpointer data) {
     }
     return NULL;
 }
+
+#ifdef LOCALCW
+void gpio_cw_sidetone_set(int level) {
+#ifdef GPIO
+  if (ENABLE_GPIO_SIDETONE) {
+    digitalWrite(SIDETONE_GPIO, level);
+  }
+#endif
+}
+
+int  gpio_cw_sidetone_enabled() {
+  return ENABLE_GPIO_SIDETONE;
+}
+#endif
+

diff --git a/iambic.c b/iambic.c
index 5a1b481856bf9d80bf402b4bdf90143a46dd1786..34817ce727cdc9d60f43a63cc73522a86ac4dbb5 100644 (file)
--- a/iambic.c
+++ b/iambic.c
@@ -62,16 +62,24 @@
  * Sep/Oct/Nov 2018, by DL1YCF Christoph van Wullen
  ***************************************************************************************************************
  *
- * a) SOME MINOR TECHNICAL ISSUES:
- * ===============================
+ * SIDE TONE GENERATION
+ * ====================
  *
- * -keyer_close was actually unused. It is now called when local CW is no longer used
- *      and "joins" (terminates) the keyer thread.
+ * Getting a delay-free side tone is absolutely necessary at elevated CW speed (say, > 20 wpm).
+ * The LINUX sound system produces a delay of up to 50 msec which is more than a dot length.
+ * Therefore we offer delay-free side tone information on the GPIO.
  *
- * - cw_keyer_spacing can now be set/un-set in the CW menu (cw_menu.c)
+ * However, LINUX is not a real-time operating system, and producing a square wave with exactly
+ * the side tone frequency is not possible (the tone is not very stable). Therefore we just
+ * give the tone information (output high = tone on, output low = tone off), and one has to
+ * build a tone generator connected to a buzzer or small speaker, and use the GPIO output line
+ * to switch the tone on and off.
+ *
+ * The volume of the CW side tone in the standard audio channel is reduced to zero while
+ * using the "GPIO side tone" feature.
  *
- * b) CW VOX
- * =========
+ * CW VOX
+ * ======
  *
  * Suppose you hit the paddle while in RX mode. In this case, the SDR automatically switches
  * to TX, and remains so until a certain time (actually cw_keyer_hang_time, can be set in
@@ -81,8 +89,8 @@
  *
  * - during a dot or dash the keyer thread simply waits and does no busy spinning.
  *
- * d) DOT/DASH MEMORY
- * ==================
+ * DOT/DASH MEMORY
+ * ===============
  *
  * For reasons explained below, it is necessary to have TWO such memories for both dot and dash,
  * they are called dot_memory/dot_held and dash_memory/dash_held. Everything explained here and below
@@ -99,8 +107,8 @@
  * dot_memory because only dot_held (but not dot_memory) is cleared in iambic mode A when both
  * paddles are released.
  *
- * e) IAMBIC MODES A AND B, AND SINGLE-LEVER PADDLES
- * =================================================
+ * IAMBIC MODES A AND B, AND SINGLE-LEVER PADDLES
+ * ==============================================
  *
  * It seems that there are lively discussions about what is what, so I distilled out the
  * following and added one clarification that becomes important when using this mode
@@ -174,6 +182,7 @@
 #include <time.h>
 #include <sys/mman.h>
 
+#include "gpio.h"
 #include "radio.h"
 #include "new_protocol.h"
 #include "iambic.h"
@@ -320,6 +329,15 @@ static void* keyer_thread(void *arg) {
        // swallow any cw_events posted during the last "cw hang" time.
         if (!kcwl && !kcwr) continue;
 
+       //
+       // If using GPIO side tone information, mute CW side tone
+       // as long as the keyer thread is active
+       //
+       if (gpio_cw_sidetone_enabled()) {
+         old_volume=cw_keyer_sidetone_volume;
+         cw_keyer_sidetone_volume=0;
+       }
+
        //
        // Normally the keyer will be used in "break-in" mode, that is, we switch to TX
        // automatically here, and after a certain "hang" time we will switch back to RX
@@ -407,6 +425,7 @@ static void* keyer_thread(void *arg) {
                       cw_key_down=960000;  // max. 20 sec to protect hardware
                       cw_key_up=0;
                       cw_key_hit=1;
+                      gpio_cw_sidetone_set(1);
                       key_state=STRAIGHT;
                     }
                 } else {
@@ -426,6 +445,7 @@ static void* keyer_thread(void *arg) {
                 if (! *kdash) {
                   cw_key_down=0;
                   cw_key_up=0;
+                  gpio_cw_sidetone_set(0);
                   key_state=CHECK;
                 }
                 break;
@@ -438,6 +458,7 @@ static void* keyer_thread(void *arg) {
                 dash_held = *kdash;
                 cw_key_down=dot_samples;
                 cw_key_up=dot_samples;
+                gpio_cw_sidetone_set(1);
                 key_state=SENDDOT;
                 break;
 
@@ -446,6 +467,7 @@ static void* keyer_thread(void *arg) {
                 // wait for dot being complete
                 //
                 if (cw_key_down == 0) {
+                  gpio_cw_sidetone_set(0);
                   key_state=DOTDELAY;
                 }
                 break;
@@ -491,6 +513,7 @@ static void* keyer_thread(void *arg) {
                dot_held = *kdot;  // remember if dot is still held at beginning of the dash
                 cw_key_down=dash_samples;
                 cw_key_up=dot_samples;
+                gpio_cw_sidetone_set(1);
                 key_state=SENDDASH;
                 break;
 
@@ -499,6 +522,7 @@ static void* keyer_thread(void *arg) {
                 // wait for dot being complete
                 //
                 if (cw_key_down == 0) {
+                  gpio_cw_sidetone_set(0);
                   key_state=DASHDELAY;
                 }
                 break;
@@ -558,6 +582,9 @@ static void* keyer_thread(void *arg) {
        //
        // If we have reduced the side tone volume, restore it!
        //
+       if (gpio_cw_sidetone_enabled()) {
+         cw_keyer_sidetone_volume = old_volume;
+       }
 
     }
     fprintf(stderr,"keyer_thread: EXIT\n");