eeprom.pio

.program eeprom

.define PUBLIC addr_bus_width 4
.define PUBLIC data_bus_width 4

    ; Get top-most address bits in memory of the array holding the EEPROM
    ; data and put them in the OSR
    pull block

    ; Now move them into the X scratch register for future use
    out x, 32

.wrap_target
    ;wait 0 pin 1
    ; Shift the address bus into the ISR
    in pins, addr_bus_width
    
    ; Shift in the top-most address bits of the array holding the EEPROM data
    ; This will cause auto-push to push the ISR to our RX FIFO
    in x, (32 - addr_bus_width)

    ; Auto-pull the data from the TX FIFO and put it on the data bus
    out pins, data_bus_width
.wrap
    
    
% c-sdk {
static inline void eeprom_init(PIO pio, uint sm, uint offset, uint pinA0, uint pinD0)
{
    pio_sm_config c = eeprom_program_get_default_config(offset);

    // Map the state machine's IN pin group to the address bus
    sm_config_set_in_pins(&c, pinA0);

    // Assign the address bus pins to PIO duty
    for(uint idx = 0; idx < eeprom_addr_bus_width; idx++)
        pio_gpio_init(pio, pinA0 + idx);

    // Set the address bus pins to 'input'
    pio_sm_set_consecutive_pindirs(pio, sm, pinA0, eeprom_addr_bus_width, false);

    // Map the state machine's OUT pin group to the data bus
    sm_config_set_out_pins(&c, pinD0, eeprom_data_bus_width);

    // Assign the data bus pins to PIO duty
    for(uint idx = 0; idx < eeprom_data_bus_width; idx++)
        pio_gpio_init(pio, pinD0 + idx);

    // Set the data bus pins to 'output'
    pio_sm_set_consecutive_pindirs(pio, sm, pinD0, eeprom_data_bus_width, true);

    // Enable auto-push after 32 bits
    sm_config_set_in_shift(&c, true, true, 32);

    // Enable auto-pull after 'eeprom_data_bus_width' bits
    sm_config_set_out_shift(&c, true, true, eeprom_data_bus_width);
    
    // 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);
}
%}