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--- guides:rfm22b [2012/01/08 10:38] – [Software] jcoxon
+++ guides:rfm22b [2013/09/04 10:15] (current) – [DominoEX] mbrejza
@@ Line 1: / Line 1: @@
 ====== RFM22B ======
+  * Modified library [[https://github.com/jamescoxon/Misc-Projects/tree/master/RFM22|RFM22 on github]]
 ===== Setup =====
@@ Line 6: / Line 7: @@
 ==== Hardware ====
+  * 3.3v
+  * Gnd
   * SPI
-  * Connect //SND// to a GPIO on the uC. This allows you to turn the radio completely on and off, if you don't need power saving then this pin can be connected to //GND// to be always on.
+    * GPIO -> //nSEL//
+    * SCK -> //SCK//
+    * MOSI -> //SDI//
+    * MISO -> //SD0//
+  * Connect //SDN// to a GPIO on the uC. This allows you to turn the radio completely on and off, if you don't need power saving then this pin can be connected to //GND// to be always on.
   * GPIO0 -> TX_ANT
   * GPIO1 -> RX_ANT
@@ Line 32: / Line 39: @@
   radio1.write(0x71, 0x00); // unmodulated carrier
+  //This sets up the GPIOs to automatically switch the antenna depending on Tx or Rx state, only needs to be done at start up
+  radio1.write(0x0b,0x12);
+  radio1.write(0x0c,0x15);
   radio1.setFrequency(434.201);
+  //Quick test
   radio1.write(0x07, 0x08); // turn tx on
   delay(1000);
@@ Line 286: / Line 298: @@
 ==== Software ====
-<code>
+<code c>
 //This sets up the GPIOs to automatically switch the antenna depending on Tx or Rx state, only needs to be done at start up
-write(0x0b,0x12);
+radio1.write(0x0b,0x12);
-write(0x0c,0x15);
+radio1.write(0x0c,0x15);
 </code>
 Info taken from the RF22 library (2)
-==== Test ====
+==== Testing ====
-  * Not yet done (lost module on last flight :-) )
+  * Rx = Yaesu FT790r no antenna
+  * Tx = RFM22b, wired up correctly, no antenna
+  * 0.5m range
+    * Before setting the GPIOs correctly in software S1
+    * After S9
+===== DominoEX =====
+With a few external components, The RFM22b can be used to send poor mans DominoEX.
+I say 'poor mans' as whilst this can be made stable for flight, it is a bit fiddly and non ideal.
+The RFM must be kept on TX all the time as the RFM22b's internal crystal oscillator circuit has a series capacitance that wanders according to the die temperature. For the best results it is better to have an external crystal and oscillator circuit which does not get affected by the changing capacitance.
+This circuit works by using the PWM output of the microprocessor, through a filter to remove the AC component and to pull the onboard crystal of the RFM22b via a varicap diode. The RFM crystal is only 30MHz and is multiplied up by approximatly 14.5 times. Since the tone spacing of Domino is only 17.5Hz at 434Mhz, the shift at 30MHz is in the order of only 1Hz per tone or about 20Hz total
+The varicap needs to be biased so that it is not being used at the bottom of its working range, so in the sample code the PWM is set to a minimum output level of say 100 and then the actual symbol is added to this.
+The code example also reprograms the timer counter so that the PWM is 8 bit fast mode so that the pwm frequency
+is easily filtered to give the dc level required by the varicap.
+==== Circuit Diagram ====
+For a full description see [[guides:crystal_pulling|Crystal Pulling]]. The sensitivity of the circuit can be reduced by reducing the value of C2
+{{:guides:crystal_pulling_rfm.png|}}
+==== Code ====
+ note: Since the Timer counter is being used for fast pwm, software serial cannot be used to talk to the GPS.
+<code c>
+        unsigned char varicode[][3] = {
+        /* Primary alphabet */
+        { 1,15, 9}, { 1,15,10}, { 1,15,11}, { 1,15,12}, { 1,15,13}, { 1,15,14}, { 1,15,15}, { 2, 8, 8},
+        { 2,12, 0}, { 2, 8, 9}, { 2, 8,10}, { 2, 8,11}, { 2, 8,12}, { 2,13, 0}, { 2, 8,13}, { 2, 8,14},
+        { 2, 8,15}, { 2, 9, 8}, { 2, 9, 9}, { 2, 9,10}, { 2, 9,11}, { 2, 9,12}, { 2, 9,13}, { 2, 9,14},
+        { 2, 9,15}, { 2,10, 8}, { 2,10, 9}, { 2,10,10}, { 2,10,11}, { 2,10,12}, { 2,10,13}, { 2,10,14},
+        { 0, 0, 0}, { 7,11, 0}, { 0, 8,14}, { 0,10,11}, { 0, 9,10}, { 0, 9, 9}, { 0, 8,15}, { 7,10, 0},
+        { 0, 8,12}, { 0, 8,11}, { 0, 9,13}, { 0, 8, 8}, { 2,11, 0}, { 7,14, 0}, { 7,13, 0}, { 0, 8, 9},
+        { 3,15, 0}, { 4,10, 0}, { 4,15, 0}, { 5, 9, 0}, { 6, 8, 0}, { 5,12, 0}, { 5,14, 0}, { 6,12, 0},
+        { 6,11, 0}, { 6,14, 0}, { 0, 8,10}, { 0, 8,13}, { 0,10, 8}, { 7,15, 0}, { 0, 9,15}, { 7,12, 0},
+        { 0, 9, 8}, { 3, 9, 0}, { 4,14, 0}, { 3,12, 0}, { 3,14, 0}, { 3, 8, 0}, { 4,12, 0}, { 5, 8, 0},
+        { 5,10, 0}, { 3,10, 0}, { 7, 8, 0}, { 6,10, 0}, { 4,11, 0}, { 4, 8, 0}, { 4,13, 0}, { 3,11, 0},
+        { 4, 9, 0}, { 6,15, 0}, { 3,13, 0}, { 2,15, 0}, { 2,14, 0}, { 5,11, 0}, { 6,13, 0}, { 5,13, 0},
+        { 5,15, 0}, { 6, 9, 0}, { 7, 9, 0}, { 0,10,14}, { 0,10, 9}, { 0,10,15}, { 0,10,10}, { 0, 9,12},
+        { 0, 9,11}, { 4, 0, 0}, { 1,11, 0}, { 0,12, 0}, { 0,11, 0}, { 1, 0, 0}, { 0,15, 0}, { 1, 9, 0},
+        { 0,10, 0}, { 5, 0, 0}, { 2,10, 0}, { 1,14, 0}, { 0, 9, 0}, { 0,14, 0}, { 6, 0, 0}, { 3, 0, 0},
+        { 1, 8, 0}, { 2, 8, 0}, { 7, 0, 0}, { 0, 8, 0}, { 2, 0, 0}, { 0,13, 0}, { 1,13, 0}, { 1,12, 0},
+        { 1,15, 0}, { 1,10, 0}, { 2, 9, 0}, { 0,10,12}, { 0, 9,14}, { 0,10,12}, { 0,11, 8}, { 2,10,15},
+        { 2,11, 8}, { 2,11, 9}, { 2,11,10}, { 2,11,11}, { 2,11,12}, { 2,11,13}, { 2,11,14}, { 2,11,15},
+        { 2,12, 8}, { 2,12, 9}, { 2,12,10}, { 2,12,11}, { 2,12,12}, { 2,12,13}, { 2,12,14}, { 2,12,15},
+        { 2,13, 8}, { 2,13, 9}, { 2,13,10}, { 2,13,11}, { 2,13,12}, { 2,13,13}, { 2,13,14}, { 2,13,15},
+        { 2,14, 8}, { 2,14, 9}, { 2,14,10}, { 2,14,11}, { 2,14,12}, { 2,14,13}, { 2,14,14}, { 2,14,15},
+        { 0,11, 9}, { 0,11,10}, { 0,11,11}, { 0,11,12}, { 0,11,13}, { 0,11,14}, { 0,11,15}, { 0,12, 8},
+        { 0,12, 9}, { 0,12,10}, { 0,12,11}, { 0,12,12}, { 0,12,13}, { 0,12,14}, { 0,12,15}, { 0,13, 8},
+        { 0,13, 9}, { 0,13,10}, { 0,13,11}, { 0,13,12}, { 0,13,13}, { 0,13,14}, { 0,13,15}, { 0,14, 8},
+        { 0,14, 9}, { 0,14,10}, { 0,14,11}, { 0,14,12}, { 0,14,13}, { 0,14,14}, { 0,14,15}, { 0,15, 8},
+        { 0,15, 9}, { 0,15,10}, { 0,15,11}, { 0,15,12}, { 0,15,13}, { 0,15,14}, { 0,15,15}, { 1, 8, 8},
+        { 1, 8, 9}, { 1, 8,10}, { 1, 8,11}, { 1, 8,12}, { 1, 8,13}, { 1, 8,14}, { 1, 8,15}, { 1, 9, 8},
+        { 1, 9, 9}, { 1, 9,10}, { 1, 9,11}, { 1, 9,12}, { 1, 9,13}, { 1, 9,14}, { 1, 9,15}, { 1,10, 8},
+        { 1,10, 9}, { 1,10,10}, { 1,10,11}, { 1,10,12}, { 1,10,13}, { 1,10,14}, { 1,10,15}, { 1,11, 8},
+        { 1,11, 9}, { 1,11,10}, { 1,11,11}, { 1,11,12}, { 1,11,13}, { 1,11,14}, { 1,11,15}, { 1,12, 8},
+        { 1,12, 9}, { 1,12,10}, { 1,12,11}, { 1,12,12}, { 1,12,13}, { 1,12,14}, { 1,12,15}, { 1,13, 8},
+        { 1,13, 9}, { 1,13,10}, { 1,13,11}, { 1,13,12}, { 1,13,13}, { 1,13,14}, { 1,13,15}, { 1,14, 8},
+        { 1,14, 9}, { 1,14,10}, { 1,14,11}, { 1,14,12}, { 1,14,13}, { 1,14,14}, { 1,14,15}, { 1,15, 8},
+        /* Secondary alphabet */
+        { 6,15, 9}, { 6,15,10}, { 6,15,11}, { 6,15,12}, { 6,15,13}, { 6,15,14}, { 6,15,15}, { 7, 8, 8},
+        { 4,10,12}, { 7, 8, 9}, { 7, 8,10}, { 7, 8,11}, { 7, 8,12}, { 4,10,13}, { 7, 8,13}, { 7, 8,14},
+        { 7, 8,15}, { 7, 9, 8}, { 7, 9, 9}, { 7, 9,10}, { 7, 9,11}, { 7, 9,12}, { 7, 9,13}, { 7, 9,14},
+        { 7, 9,15}, { 7,10, 8}, { 7,10, 9}, { 7,10,10}, { 7,10,11}, { 7,10,12}, { 7,10,13}, { 7,10,14},
+        { 3, 8, 8}, { 4,15,11}, { 5, 8,14}, { 5,10,11}, { 5, 9,10}, { 5, 9, 9}, { 5, 8,15}, { 4,15,10},
+        { 5, 8,12}, { 5, 8,11}, { 5, 9,13}, { 5, 8, 8}, { 4,10,11}, { 4,15,14}, { 4,15,13}, { 5, 8, 9},
+        { 4,11,15}, { 4,12,10}, { 4,12,15}, { 4,13, 9}, { 4,14, 8}, { 4,13,12}, { 4,13,14}, { 4,14,12},
+        { 4,14,11}, { 4,14,14}, { 5, 8,10}, { 5, 8,13}, { 5,10, 8}, { 4,15,15}, { 5, 9,15}, { 4,15,12},
+        { 5, 9, 8}, { 4,11, 9}, { 4,12,14}, { 4,11,12}, { 4,11,14}, { 4,11, 8}, { 4,12,12}, { 4,13, 8},
+        { 4,13,10}, { 4,11,10}, { 4,15, 8}, { 4,14,10}, { 4,12,11}, { 4,12, 8}, { 4,12,13}, { 4,11,11},
+        { 4,12, 9}, { 4,14,15}, { 4,11,13}, { 4,10,15}, { 4,10,14}, { 4,13,11}, { 4,14,13}, { 4,13,13},
+        { 4,13,15}, { 4,14, 9}, { 4,15, 9}, { 5,10,14}, { 5,10, 9}, { 5,10,15}, { 5,10,10}, { 5, 9,12},
+        { 5, 9,11}, { 3, 8,12}, { 4, 9,11}, { 4, 8,12}, { 4, 8,11}, { 3, 8, 9}, { 4, 8,15}, { 4, 9, 9},
+        { 4, 8,10}, { 3, 8,13}, { 4,10,10}, { 4, 9,14}, { 4, 8, 9}, { 4, 8,14}, { 3, 8,14}, { 3, 8,11},
+        { 4, 9, 8}, { 4,10, 8}, { 3, 8,15}, { 4, 8, 8}, { 3, 8,10}, { 4, 8,13}, { 4, 9,13}, { 4, 9,12},
+        { 4, 9,15}, { 4, 9,10}, { 4,10, 9}, { 5,10,12}, { 5, 9,14}, { 5,10,12}, { 5,11, 8}, { 7,10,15},
+        { 7,11, 8}, { 7,11, 9}, { 7,11,10}, { 7,11,11}, { 7,11,12}, { 7,11,13}, { 7,11,14}, { 7,11,15},
+        { 7,12, 8}, { 7,12, 9}, { 7,12,10}, { 7,12,11}, { 7,12,12}, { 7,12,13}, { 7,12,14}, { 7,12,15},
+        { 7,13, 8}, { 7,13, 9}, { 7,13,10}, { 7,13,11}, { 7,13,12}, { 7,13,13}, { 7,13,14}, { 7,13,15},
+        { 7,14, 8}, { 7,14, 9}, { 7,14,10}, { 7,14,11}, { 7,14,12}, { 7,14,13}, { 7,14,14}, { 7,14,15},
+        { 5,11, 9}, { 5,11,10}, { 5,11,11}, { 5,11,12}, { 5,11,13}, { 5,11,14}, { 5,11,15}, { 5,12, 8},
+        { 5,12, 9}, { 5,12,10}, { 5,12,11}, { 5,12,12}, { 5,12,13}, { 5,12,14}, { 5,12,15}, { 5,13, 8},
+        { 5,13, 9}, { 5,13,10}, { 5,13,11}, { 5,13,12}, { 5,13,13}, { 5,13,14}, { 5,13,15}, { 5,14, 8},
+        { 5,14, 9}, { 5,14,10}, { 5,14,11}, { 5,14,12}, { 5,14,13}, { 5,14,14}, { 5,14,15}, { 5,15, 8},
+        { 5,15, 9}, { 5,15,10}, { 5,15,11}, { 5,15,12}, { 5,15,13}, { 5,15,14}, { 5,15,15}, { 6, 8, 8},
+        { 6, 8, 9}, { 6, 8,10}, { 6, 8,11}, { 6, 8,12}, { 6, 8,13}, { 6, 8,14}, { 6, 8,15}, { 6, 9, 8},
+        { 6, 9, 9}, { 6, 9,10}, { 6, 9,11}, { 6, 9,12}, { 6, 9,13}, { 6, 9,14}, { 6, 9,15}, { 6,10, 8},
+        { 6,10, 9}, { 6,10,10}, { 6,10,11}, { 6,10,12}, { 6,10,13}, { 6,10,14}, { 6,10,15}, { 6,11, 8},
+        { 6,11, 9}, { 6,11,10}, { 6,11,11}, { 6,11,12}, { 6,11,13}, { 6,11,14}, { 6,11,15}, { 6,12, 8},
+        { 6,12, 9}, { 6,12,10}, { 6,12,11}, { 6,12,12}, { 6,12,13}, { 6,12,14}, { 6,12,15}, { 6,13, 8},
+        { 6,13, 9}, { 6,13,10}, { 6,13,11}, { 6,13,12}, { 6,13,13}, { 6,13,14}, { 6,13,15}, { 6,14, 8},
+        { 6,14, 9}, { 6,14,10}, { 6,14,11}, { 6,14,12}, { 6,14,13}, { 6,14,14}, { 6,14,15}, { 6,15, 8},
+     };
+     void dominoex_txsym(uint8_t sym)
+    {
+        _sym = (_sym + 2 + sym) % 18;
+        analogWrite(radio, 8*_sym+100);
+        delay(64);
+    }
+    void dominoex_txchar(uint16_t code)
+   {
+        uint8_t i, c;
+        for(i = 0; i < 3; i++)
+        {
+                c = varicode[code][i];
+                if(i && !(c & 0x8)) break;
+                dominoex_txsym(c);
+        }
+  }
+   void dominoex_string(char *s)
+    {
+        for(; *s; s++) dominoex_txchar(*s);
+    }
+   void setPwmFrequency(int pin, int divisor) {
+    byte mode;
+    if(pin == 5 || pin == 6 || pin == 9 || pin == 10) {
+    switch(divisor) {
+    case 1:
+      mode = 0x01;
+      break;
+    case 8:
+      mode = 0x02;
+      break;
+    case 64:
+      mode = 0x03;
+      break;
+    case 256:
+      mode = 0x04;
+      break;
+    case 1024:
+      mode = 0x05;
+      break;
+    default:
+      return;
+    }
+    if(pin == 5 || pin == 6) {
+      TCCR0B = TCCR0B & 0b11111000 | mode;
+    }
+    else {
+      TCCR1B = TCCR1B & 0b11111000 | mode;
+    }
+  }
+  else if(pin == 3 || pin == 11) {
+    switch(divisor) {
+    case 1:
+      mode = 0x01;
+      break;
+    case 8:
+      mode = 0x02;
+      break;
+    case 32:
+      mode = 0x03;
+      break;
+    case 64:
+      mode = 0x04;
+      break;
+    case 128:
+      mode = 0x05;
+      break;
+    case 256:
+      mode = 0x06;
+      break;
+    case 1024:
+      mode = 0x7;
+      break;
+    default:
+      return;
+    }
+    TCCR2B = TCCR2B & 0b11111000 | mode;
+   }
+ }
+ void setup()  {
+  pinMode(radio, OUTPUT);
+  setPwmFrequency(9, 1);
+  }
+ void loop()  {
+  dominoex_string("The quick brown fox jumped over the lazy dog \n");
+ }
+</code>
+==== Tuning ====
+Since the circuit will have pulled the oscillator off frequency you will need to find the signal as it is not where the set frequency call says it will be.
+  * connect a receiver to fldigi and select dominoex16.
+  * Turn down the volume as the sound is like two squirrels in a bag and gets rather irritating after a short time.
+  * move the cursors over the tones as per the picture below.
+  * Adjust the potentiometer so that the overall width of the tones are just inside the red lines.
+  * Keep adjusting till the message becomes readable.
+{{:guides:domfldig.png?200|}}
+This isn't quite as easy as it sounds as the bias voltage is also being set by the potentiometer so it will be necessary to retune the receiver and move the reference lines as you try to adjust the width of the tones
+==== Possible improvements. ====
+  * Have a separate bias voltage potentiometer to make it easier to set up.
+  * External Crystal oscillator
+  * Pre amp for level shifting and improved filtering.
+=== Thanks to ===
+Fsphil and UPU for the DominoEX code.
-==== Links ====
+===== Links =====
   - [[http://arduino.cc/forum/index.php?topic=50533.15]]
   - [[http://www.open.com.au/mikem/arduino/RF22/]]
+  - [[https://github.com/niloc132/arduino-rfm22]]
+  - [[projects:picoatlas:picoatlasvi|PicoAtlas6]]