Add MFM floppy emulator #34
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Later, the RP2040 PIO peripheral will want to use this compact flux representation.
though it's not mfm-flux
I used jumper wires between my metro & a genuine greaseweazle. gw host software does display a warning twice for each track: ``` Unknown mark 4e ``` This is very proof of concept quality at the moment but hey it's there!
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As a milestone, greasweazle can now grok the flux produced by the USB floppy sketch. dunno what's up with the unknown markers yet. |
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Now, real data from the SD card is returned. The side number is not used/checked yet. |
jepler
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this also enables working on the featherwing, with no defined PIN_CARD_CS; in this case, test data is output instead of a real disk image.
Otherwise, we end up doing extra work: A sequential read will go from e.g., track 0 side 1 to track 1 side 0. But there's a moment in there where the inputs to floppsy are "track 1 side 1", so we flux-convert T1.1 and then immediately have to convert T1.0. This would often make GW report that it failed reading a track the first time (T70.0 in this case): ``` T69.1: IBM MFM (18/18 sectors) from Raw Flux (156238 flux in 400.36ms) T70.0: IBM MFM (0/18 sectors) from Raw Flux (78084 flux in 236.36ms) T70.0: IBM MFM (18/18 sectors) from Raw Flux (311958 flux in 836.88ms) (Retry #1.1) ``` After this change, GW ripped a whole floppy without needing to retry and without getting any weird transient failures.
Tested: 360k, 720k & 1.44M
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@ladyada this is ready for review, though it still needs to be tested with a real PC host as well. My setup:
#pragma once
// old featherwing pinout
#define DENSITY_PIN A0 // IDC 2
#define INDEX_PIN A1 // IDC 8
#define SELECT_PIN A2 // IDC 12
#define MOTOR_PIN A3 // IDC 16
#define DIR_PIN 24 // IDC 18
#define STEP_PIN 25 // IDC 20
#define WRDATA_PIN 13 // IDC 22
#define WRGATE_PIN 12 // IDC 24
#define TRK0_PIN 11 // IDC 26
#define PROT_PIN 10 // IDC 28
#define READ_PIN 9 // IDC 30
#define SIDE_PIN D6 // IDC 32
#define READY_PIN D5 // IDC 34
#define PIN_CARD_CS D4 // modified adalogger featherwing
#define DISKCHANGE_PIN 1 // RXthe code should probably be polished up some (and then a lot more when we have floppsy with LCD & 4 buttons) but I think the functionality is there. I tested all 4 common sizes (360, 1200, 720, 1440) with GW decoding them all just fine. These were basic images I created on my computer with a FAT image creator (mkfs.fat), no content on them. |
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