Add "EraseFlux" command to greaseweazle firmware

[gilmod714]

I built the pi pico GW version and it works OK for read/write with 4.7k pullup resistor on read-data line (it's a bit slow, but it works) , however, I noticed that, the "erase" disk function does not work, or not supported ?!

gw.exe erase --device=COM44

Great work by the way ..

Thank you

[criscrafter]

Are you pulling the pin up to 5V or 3.3V?
Sadly I don't have a solution for you, but I can't get mine to work...

[gilmod714]

I'm using 3.3v pull .. but I don't think it's that .. it seems to me the "erase" function isn't included in the sketch! .. the read/write works ok though .. but much slower than the stm32 for sure.. I'm using RP2040 zero/and also tried it on pi pico ..

[jepler]

EraseFlux (command #17) is not presently supported by our gw-compatible firmware.

In the official gw firmware, it appears this mode works simply by turning on the write gate and leaving it on for a specified time:

/*
 * ERASE PATH
 */

static uint8_t floppy_erase_prep(const struct gw_erase_flux *ef)
{
    op_delay_wait(DELAY_write);

    if (get_wrprot() == LOW)
        return ACK_WRPROT;

    write_pin(wgate, TRUE);

    floppy_state = ST_erase_flux;
    flux_op.status = ACK_OKAY;
    flux_op.end = time_now() + time_from_samples(ef->ticks);

    return ACK_OKAY;
}

static void floppy_erase(void)
{
    if (time_since(flux_op.end) < 0)
        return;

    floppy_flux_end();

    /* ACK with Status byte. */
    u_buf[0] = flux_op.status;
    floppy_state = ST_command_wait;
    floppy_end_command(u_buf, 1);
}```

I've marked this "help wanted" because I'd be thrilled if someone contributed the implementation.