Final PA RXTX and LPF band control - the Caprice system

The Caprice system

I previously gave a set of sketch code for the VFO or QRP to control the PA, to switch it from RX to TX and set the LPF to a band, 40, 30. 20m. The control signals are carried on two wires of a 4-way jack. The two control bits were connected to Arduino pins 12 & 13. But these pins, I realise are used in the QRP for TX & RX switching and so cannot be used for PA control. So I have changed to A0 & A1 pins.

This has meant a change also to the GPS sketches so the TX and RX serial data is read from these pins.

So the new code is as described below:

Caprice System

The Caprice system uses a 4 wire bus to supply power and signals. These are carried on a 4-way 3.5mm jack. The signals connect to Arduino A0 & A1.

Jack	Power/Signal	Socket Wire
Body		GND		Brown (B)
Ring		PIN A1	Yellow (Y)
Ring  	PIN A0	Orange (O)
Tip		5V OUT	Red (R)

OLED	Power/Signal	Wire
GND				Black (K)
VDD				Brown (B)
SCK				Red (R)
SDA				Orange (O)

PA Connections (top)
OLED
________________
o o o o o o o o |
O R B K
SDA VDD
  SCK GND

Jack
o o o o o o o o |
Y O R B     - -
A1  5V      12V
  A0  GND     GND

Outputs from GPS
A GPS uses the following connections:

GND
A0 - RX from GPS
A1 - TX to GPS
5V

Output from sketches
In the Caprice system sketches use the following connections:

GND
A0 - LSB of command (was 12)
A1 - MSB of command (was 13)
5V out

The output signals encode the signals to set the PA into one of 4 modes (0, 1, 2 & 3):

// modes, 00, 01, 10, 11 on A1, A0
#define RX 0
#define TX40 1
#define TX30 2
#define TX20 3

// SETUP
// include in setup...
  // jack PA control outputs
  pinMode(A0, OUTPUT);
  pinMode(A1, OUTPUT);

  // init band, RX
  setPA(TX40);                    // mode 40m, set PA LPF
  setPA(RX);                      // back to mode RX

This function outputs the modes to the PA.

// SET PA MODE
// modes 0, 1, 2, 3 output on A1, A0, active LOW
void setPA(int m) {
  // set mode
  switch (m) {
    case 0:
      digitalWrite(A1, HIGH);
      digitalWrite(A0, HIGH);    // RX
      break;
    case 1:
      digitalWrite(A1, HIGH);
      digitalWrite(A0, LOW);    // TX40
      break;
    case 2:
      digitalWrite(A1, LOW);
      digitalWrite(A0, HIGH);   // TX30
      break;
    case 3:
      digitalWrite(A1, LOW);
      digitalWrite(A0, LOW);    // TX20
      break;
  }
}

Relay wiring

		o------- 40m
in/Out---o/             /B6
		o-----|
	|----------|
	|	o------- 30m
	|---o/             /B7
		o------- 20m

PA Input
The PA inputs the signals and decodes them to modes (0, 1, 2 or 3):

// CONNECTIONS
// relay outputs (active HIGH)
#define PTT 5
#define B6 6
#define B7 7

// PARAMETERS
// modes
#define RX 0
#define TX40 1
#define TX30 2
#define TX20 3

// GLOBAL VARIABLES
char disp[][4] = {"", "40m", "30m", "20m"};    // display
byte mode, band;                               // mode 0-3, band 1-3

SETUP includes

  pinMode(A0, INPUT_PULLUP);     // bus LSB
  pinMode(A1, INPUT_PULLUP);     // bus MSB
  pinMode(PTT, OUTPUT);   // T/R relay
  pinMode(B6, OUTPUT);    // BAND 6
  pinMode(B7, OUTPUT);    // BAND 7

  // init 40m RX
  swPA(TX40);            // mode 40m, set LPF
  swPA(RX);              // back to mode RX


The mode input is read from A1 & A0

  // read mode input
  mode = getMode(digitalRead(A1), digitalRead(A0)); // read 0000 00xx

/ GET MODE
// A1 & A0 gets mode, returns 0-3 (RX-TX20)
byte getMode(bool b1, bool b0) {
  if (b1 == HIGH && b0 == HIGH) return RX;     // 0 RX
  if (b1 == HIGH && b0 == LOW)  return TX40;   // 1 TX 40m
  if (b1 == LOW && b0 == HIGH)  return TX30;   // 2 TX 30m
  if (b1 == LOW && b0 == LOW)   return TX20;   // 3 TX 20m
}

The mode is used to switch the TX/TX PTT relay (Antenna to PA or RX) and the LPF relays.

// SWITCH PA
// set PTT & LPF relays (HIGH = on), set band
void swPA(byte m) {
  // first check RX or TX
  if (m == RX)
    digitalWrite(PTT, LOW);              // RX
  else {
    digitalWrite(PTT, HIGH);             // TX

    // chose LPF freq
    switch (m) {
      case TX40:
        digitalWrite(B6, LOW);           // 40m
        digitalWrite(B7, LOW);
        break;
      case TX30:
        digitalWrite(B6, HIGH);          // 30m
        digitalWrite(B7, LOW);
        break;
      case TX20:
        digitalWrite(B6, HIGH);          // 20m
        digitalWrite(B7, HIGH);
        break;
    }
    band = m;                            // set band 1-3 for display
  }
}

The PA display shows UL Band when in RX mode, and "TX" when transmitting.

//  PICTURE LOOP
// Display band or "TX"
void dispUpdate() {
  oled.firstPage();
  do {
    dispMsg(60, 0, "PA");
    if (mode == RX) {                 // if RX
      dispMsgUL(30, 15, disp[band]); // display band
      dispMsgL(50, 50, "RX");
    }
    else {
      dispMsgUL(45, 15, "TX");       // otherwise show "TX"
      dispMsgL(50, 50, disp[band]);
    }
  } while (oled.nextPage());
}