lightning_rx.pio

.program lightning_rx

; 1 NOP is 0.5us

.side_set 1 opt
receive:

    ; Set pin to input
    SET PINDIRS 0 side 0
    MOV ISR NULL

receive_next_byte:
    MOV ISR NULL
    ; Set data counter
    SET X 7

data_loop:
    ; Now we wait for the falling flank at the start of the bit
    ; Then we wait 3us
    WAIT 0 PIN 0 side 1 [5]
    ; Read (inverted!!) bit
    ; We wait 4us so we are at the position of either the finishing flank OR the stop bit
    IN PINS 1 side 0 [7]
    NOP
    ; if this is NOT a stop bit we continue receive
    JMP PIN continue_receive
    ; if it IS a stop bit, we restart!
    WAIT 1 PIN 0 side 1
    NOP
    JMP receive_next_byte side 0
continue_receive:
    WAIT 1 PIN 0 side 1
    JMP X-- data_loop side 0

; if we get here we have received 8 bits, time to push!
    PUSH NOBLOCK
    JMP receive_next_byte

% c-sdk {
static inline pio_sm_config lightning_rx_program_init(PIO pio, uint sm, uint offset, uint pin, float clkdiv) {


 //pio_sm_set_pins_with_mask(pio, sm, 1u << pin_rx, 1u << pin_rx);
    pio_sm_set_pindirs_with_mask(pio, sm, 1u << 19, 1u << 19);
    pio_sm_set_pindirs_with_mask(pio, sm, 1u << 19, 0u << pin);
    pio_gpio_init(pio, 19);


    pio_sm_config c = lightning_rx_program_get_default_config(offset);

    // Map the state machine's OUT pin group to one pin, namely the `pin`
    // parameter to this function.
    //sm_config_set_out_pins(&c, pin, 1);
    sm_config_set_set_pins(&c, pin, 1);
    sm_config_set_in_pins(&c, pin);
sm_config_set_jmp_pin(&c, pin);
    //pio_sm_set_sideset_pins(pio, sm, 19);
    sm_config_set_sideset_pins(&c, 19);
    sm_config_set_in_shift(&c, false, false, 32);
    sm_config_set_out_shift(&c, true, false, 32);
    
    // Set this pin's GPIO function (connect PIO to the pad)
    pio_gpio_init(pio, pin);
    pio_gpio_init(pio, 19);
    // Set the pin direction to output at the PIO
    //pio_sm_set_consecutive_pindirs(pio, sm, pin, 1, false);
    sm_config_set_clkdiv(&c, clkdiv);
    

    // Load our configuration, and jump to the start of the program
    pio_sm_init(pio, sm, offset, &c);
    // Set the state machine running
    pio_sm_set_enabled(pio, sm, true);
    return c;
}
%}