Improved management of FM audio volume on MD-UV3x0.

Fix #160.

openrtx/src/rtx/OpMode_FM.cpp

@@ -39,16 +39,17 @@
 #ifdef PLATFORM_MDUV3x0
 void _setVolume()
 {
-    // Volume level range is 0 - 255, by right shifting by 3 we get a value in
-    // range 0 - 31.
+    static uint8_t oldVolume = 0xFF;
     uint8_t volume = platform_getVolumeLevel();
-    volume >>= 3;
 
-    if(volume >= 1)
-    {
-        // Setting HR_C6000 volume to 0 = max volume
-        HR_C6000::instance().setDacGain(volume);
-    }
+    if(volume == oldVolume)
+        return;
+
+    // Apply new volume level, map 0 - 255 range into -31 to 31
+    int8_t gain = ((int8_t) (volume / 4)) - 31;
+    HR_C6000::instance().setDacGain(gain);
+
+    oldVolume = volume;
 }
 #endif
 
@@ -85,6 +86,11 @@ void OpMode_FM::update(rtxStatus_t *const status, const bool newCfg)
 {
     (void) newCfg;
 
+    #ifdef PLATFORM_MDUV3x0
+    // Set output volume by changing the HR_C6000 DAC gain
+    _setVolume();
+    #endif
+
     // RX logic
     if(status->opStatus == RX)
     {
@@ -114,12 +120,6 @@ void OpMode_FM::update(rtxStatus_t *const status, const bool newCfg)
             audioPath_release(rxAudioPath);
             sqlOpen = false;
         }
-
-        #ifdef PLATFORM_MDUV3x0
-        // Set output volume by changing the HR_C6000 DAC gain
-        if(sqlOpen == true) _setVolume();
-        #endif
-
     }
     else if((status->opStatus == OFF) && enterRx)
     {

platform/drivers/baseband/HR_C6000_UV3x0.cpp

@@ -102,7 +102,7 @@ void HR_Cx000< M >::init()
     writeReg(M::CONFIG, 0x65, 0x0A);    // Undocumented register
     writeReg(M::CONFIG, 0x1D, 0xFF);    // Local unaddress, mask unaddress (?)
     writeReg(M::CONFIG, 0x1E, 0xF1);    // Broadcast RX address, broadcast address mask
-    writeReg(M::CONFIG, 0xE2, 0x06);    // Mic preamp disabled, anti-pop enabled
+    writeReg(M::CONFIG, 0xE2, 0x00);    // DAC off, mic preamp disabled
     writeReg(M::CONFIG, 0xE4, 0x27);    // Lineout gain, first and second stage mic gain
     writeReg(M::CONFIG, 0xE3, 0x52);    // Internal ADC and DAC passthrough enable
     writeReg(M::CONFIG, 0xE5, 0x1A);    // Undocumented register
@@ -172,7 +172,6 @@ void HR_Cx000< M >::fmMode()
     writeReg(M::CONFIG, 0x81, 0x04);    // Interrupt mask
     writeReg(M::CONFIG, 0xE5, 0x1A);    // Undocumented register
     writeReg(M::CONFIG, 0xE4, 0x27);    // Lineout gain, first and second stage mic gain
-    writeReg(M::CONFIG, 0xE2, 0x06);    // Mic preamp disabled, anti-pop enabled
     writeReg(M::CONFIG, 0x34, 0x98);    // FM bpf enabled, 25kHz bandwidth
     writeReg(M::CONFIG, 0x60, 0x00);    // Disable both analog and DMR transmission
     writeReg(M::CONFIG, 0x1F, 0x00);    // Color code, encryption disabled
@@ -187,8 +186,6 @@ void HR_Cx000< M >::fmMode()
     sendSequence(initSeq7, sizeof(initSeq7));
     writeReg(M::CONFIG, 0x11, 0x80);    // Local channel mode
     writeReg(M::CONFIG, 0xE0, 0xC9);    // Codec enabled, LineIn1, LineOut2, I2S slave mode
-
-    writeReg(M::CONFIG, 0x37, 0x81);    // DAC gain
 }
 
 template< class M >
@@ -218,7 +215,6 @@ void HR_Cx000< M >::startAnalogTx(const TxAudioSource source, const FmConfig cfg
     writeReg(M::AUX,    0x50, 0x00);
     writeReg(M::AUX,    0x51, 0x00);
     writeReg(M::CONFIG, 0x3E, 0x08);    // FM Modulation frequency deviation coefficient at the receiving end
-    writeReg(M::CONFIG, 0x37, 0x8C);    // DAC gain
     writeReg(M::CONFIG, 0x60, 0x80);    // Start analog transmission
 }
 
@@ -227,9 +223,7 @@ void HR_Cx000< M >::stopAnalogTx()
 {
     writeReg(M::CONFIG, 0x60, 0x00);    // Stop analog transmission
     writeReg(M::CONFIG, 0xE0, 0xC9);    // Codec enabled, LineIn1, LineOut2, I2S slave mode
-    writeReg(M::CONFIG, 0xE2, 0x06);    // Mic preamp disabled, anti-pop enabled
     writeReg(M::CONFIG, 0x34, 0x98);    // FM bpf enabled, 25kHz bandwidth
-    writeReg(M::CONFIG, 0x37, 0x81);    // DAC gain
     writeReg(M::CONFIG, 0x26, 0xFD);    // Undocumented register, enable FM receive
 }
 

platform/drivers/baseband/HR_Cx000.cpp

@@ -32,18 +32,28 @@ bool Cx000_uSpiBusy()
 }
 
 template <>
-void HR_Cx000< C5000_SpiOpModes >::setDacGain(uint8_t value)
+void HR_Cx000< C5000_SpiOpModes >::setDacGain(int8_t gain)
 {
     // TODO: "DALin" register for HR_C5000 is not documented.
-    (void) value;
+    (void) gain;
 }
 
 template <>
-void HR_Cx000< C6000_SpiOpModes >::setDacGain(uint8_t value)
+void HR_Cx000< C6000_SpiOpModes >::setDacGain(int8_t gain)
 {
-    if(value < 1)  value = 1;
-    if(value > 31) value = 31;
-    writeReg(C6000_SpiOpModes::CONFIG, 0x37, (0x80 | value));
+    // If gain is at minimum, just turn off DAC output and return
+    if(gain <= -31)
+    {
+        writeReg(C6000_SpiOpModes::CONFIG, 0xE2, 0x00);
+        return;
+    }
+
+    uint8_t value = 0x80 | (((uint8_t) gain) & 0x1F);
+    if(gain > 0)
+        value |= 0x40;
+
+    writeReg(C6000_SpiOpModes::CONFIG, 0x37, value);    // DAC gain
+    writeReg(C6000_SpiOpModes::CONFIG, 0xE2, 0x02);     // Enable DAC
 }
 
 template <>

platform/drivers/baseband/HR_Cx000.h

@@ -146,12 +146,12 @@ public:
     }
 
     /**
-     * Set the gain of the audio DAC stage. This value affects the sound volume
-     * in RX mode.
+     * Set the gain of the audio DAC stage, each step corresponds to an 1.5dB
+     * variation.
      *
-     * @param value: gain value. Allowed range is 1-31.
+     * @param gain: gain value. Allowed range is from -31 to +31.
      */
-    void setDacGain(uint8_t value);
+    void setDacGain(int8_t gain);
 
     /**
      * Set the gain for the incoming audio from both the microphone and line-in