buildUartByte()

u8 fl::anonymous_namespace{uart_wave_encoder.cpp.hpp}::buildUartByte	(	u8	pulses_a,
		u8	pulses_b,
		u8	pulses_per_bit = 5 )

Build a UART data byte from two LED bit pulse counts.

Constructs the 8-bit UART data value that, with TX inversion and LSB-first transmission, produces the desired wire waveform.

Wire model (10 bits with TX inversion): [START=H] [~D0] [~D1] [~D2] [~D3] [~D4] [~D5] [~D6] [~D7] [STOP=L]

LED bit A occupies positions 0-4 (START + D0..D3): START is always HIGH (1 pulse guaranteed) D0..D3 set HIGH for (pulses_a - 1) additional pulses, then LOW

LED bit B occupies positions 5-9 (D4..D7 + STOP): D4 must be HIGH for leading edge (1 pulse guaranteed) D5..D7 set HIGH for (pulses_b - 1) additional pulses, then LOW STOP is always LOW

Parameters

pulses_a	HIGH pulse count for LED bit A [1, 4]
pulses_b	HIGH pulse count for LED bit B [1, 4]

Returns

UART data byte value

Definition at line 66 of file uart_wave_encoder.cpp.hpp.

                                                                               {
    // Build the desired 2P-bit wire pattern (with TX inversion), where
    // P = pulses_per_bit. Wire positions:
    //   [0=START] [1=~D0] ... [2P-2=~D(2P-3)] [2P-1=STOP]
    //
    // LED bit A (pos 0..P-1): pulses_a HIGH bits, then LOW
    // LED bit B (pos P..2P-1): pulses_b HIGH bits, then LOW (STOP=L)
 
    const int P = static_cast<int>(pulses_per_bit);
    int wire[10]; // max frame = 10 (P=5)
 
    // LED bit A: pulses_a HIGH bits starting from position 0
    for (int i = 0; i < P; i++) {
        wire[i] = (i < static_cast<int>(pulses_a)) ? 1 : 0;
    }
 
    // LED bit B: pulses_b HIGH bits starting from position P
    for (int i = 0; i < P; i++) {
        wire[P + i] = (i < static_cast<int>(pulses_b)) ? 1 : 0;
    }
 
    // Convert wire pattern back to UART data byte
    // Wire[0] = START (inverted) = always H -> no control needed
    // Wire[1..2P-2] = ~D0..~D(2P-3) (inverted data, LSB first)
    // Wire[2P-1] = STOP (inverted) = always L -> no control needed
    //
    // So: wire[1+i] = ~D_i -> D_i = ~wire[1+i] = wire[1+i] ? 0 : 1
    u8 byte_val = 0;
    const int data_bits = 2 * P - 2;
    for (int i = 0; i < data_bits; i++) {
        int data_bit = wire[1 + i] ? 0 : 1; // Invert: wire HIGH -> data 0
        byte_val |= static_cast<u8>(data_bit << i); // LSB first
    }
 
    return byte_val;
}

References buildUartByte(), fl::FL_NO_EXCEPT, and fl::P().

Referenced by buildUartByte().

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