timer improvement

area3001 · May 11, 2022 · 9f6fa64 · 9f6fa64
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diff --git a/Documentation/Communication.md b/Documentation/Communication.md
@@ -0,0 +1,99 @@
+# Communication over the wire and IR
+
+## Infrared
+Infrared data is transmitted on 940 nm with a 38khz carrier wave.
+
+## Protocol
+IR and badgelink share the same protocol. The protocol they use is the standard JVC IR protocol. https://www.sbprojects.net/knowledge/ir/jvc.php  
+This protocol is simple to implement and gives us 16 bits of data.
+
+The implementation on the Time Blaster is compatible with the JVC protocol but has a few small differences:
+ - Receiving/decoding only measure the full pulse (HLH) length. This is possible because the JVC protocol has unique pulse lengths for each type of signal (Start, 0, 1)
+ - Data is not split into a Address and command area but in a data(12bit) and CRC(4bit) area.
+
+# Data 
+
+## data packet
+The Time Blaster uses this 16 bit packet for all communication between blasters and also to and from the badge.
+
+| Bit        | Name        | Use   |
+| ---------: |-------------| -----|
+| 0 | Team Color Red   | Set/get blaster team color |
+| 1 | Team Color Green |  |
+| 2 | Team Color Blue  |  |
+| 3 | Trigger Status | Indicate if a shot was fired <br> also used for disabling the trigger |
+| 4 | Command_0 | Send commands like animations |
+| 5 | Command_1 |  |
+| 6 | Command_2 |  |
+| 7 | Command_3 |  |
+| 8 | Parameter_0 | 4 parmeter bits for the command given |
+| 9 | Parameter_1 |  |
+| 10 | Parameter_2 |  |
+| 11 | Parameter_3 |  |
+| 12 | CRC_0 | Checksum for data validation |
+| 13 | CRC_1 |  |
+| 14 | CRC_2 |  |
+| 15 | CRC_3 |  |
+
+Depending on the source of the packet the blaster allows or rejects some commands.
+
+## Team Color
+
+### Badge to Blaster
+000 : team is set by the hardware switch.  
+All other: team is set by this.
+
+### Blaster to Badge
+Indicates the current selected team. The can be the team selected by switch or the team set by the badge in an earlier packet.  
+value 000 is not allowed.
+
+### Blaster to Blaster
+Carries the team color of the blaster that fired.   
+value 000 is not allowed.
+
+## Trigger Status
+
+### Badge to Blaster
+0: Trigger on the blaster is disabled. Team LED is turned off  
+1: Trigger on the blaster is enabled. Team LED is turned on
+
+### Blaster to Badge
+1: Blaster just fired a pulse
+0: All other cases
+
+### Blaster to Blaster
+Always 1
+
+## Command and Parameters
+
+To be completed.
+
+The blaster can send and receive commands. Each command can have a 4 bit parameter.
+
+Some examples:
+* Shoot
+* Heal
+* Set IR Channel 
+* Set Fire Type (Damage|Healing)
+* Set Game mode (Timeout when hit, zombie mode, slave(badge controlled))
+* Got Hit
+* Play Animation
+* Team Switch Changed
+* Chatter (Blasters start a short "discussion" about the meaning of life)
+* Pull trigger (force blaster to shoot)
+* Blaster ready
+
+## CRC
+This is the calculation used to get the check.
+
+d0..d11 are the bits in position 0..11  
+the 4 crc bits will be added so crc_0 will be bit_12, crc_1 => bit_13 etc.
+
+```c++
+  crc[0] = d11 ^ d10 ^ d9 ^ d8 ^ d6 ^ d4 ^ d3 ^ d0;  
+  crc[1] = d8  ^ d7  ^ d6 ^ d5 ^ d3 ^ d1 ^ d0 ^ 1;  
+  crc[2] = d9  ^ d8  ^ d7 ^ d6 ^ d4 ^ d2 ^ d1 ^ 1;  
+  crc[3] = d10 ^ d9  ^ d8 ^ d7 ^ d5 ^ d3 ^ d2;  
+```
+
+Applying the same function to a packet with a CRC the CRC should become 0 if no corruption was detected.
diff --git a/Firmware/Firmware.ino b/Firmware/Firmware.ino
@@ -132,15 +132,17 @@ void transmit_raw(unsigned int data, bool ir_out, bool badgelink_out)
 void setup_ir_carrier()
 {
   /* Setup Timer 1 to toggle the IR-LED D1 at 38khz
-    Note: this will generate a wave at 38.5khz due to limitations of this timer.
+     This will generate a wave of approximately 38.1khz.
+     http://www.8bit-era.cz/arduino-timer-interrupts-calculator.html
   */
   cli();              // Stop interrupts while we set up the timer
   TCCR1B = B00000000; // Stop Timer/Counter1 clock by setting the clock source to none.
   TCCR1A = B00000000; // Set Timer/Counter1 to normal mode.
   TCNT1 = 0;          // Set Timer/Counter1 to 0
-  OCR1A = 25;         // Set the Output Compare A for Timer/Counter1, 100 Hz
+  OCR1A = 209; // = 16000000 / (1 * 76190.47619047618) - 1 (must be <65536)
   TCCR1A = B01000100; // Set Timer/Counter1 to CTC mode. Set OC1A to toggle.
-  TCCR1B = B00001010; // Start Timer/Counter1 clock by setting the source to CPU source. Set prescalar to 1/8 (2Mhz).
+  TCCR1B |= (1 << WGM12);
+  TCCR1B |= (0 << CS12) | (0 << CS11) | (1 << CS10);
   sei();              // allow interrupts
 }