6502.org

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; assumes 65816 native mode upon entry and exit.
; send one bit to WS2812B chain.
; short pulse for zero and long pulse for one.

SEC
XCE
NOP
ROL A
XCE
NOP
CLC
XCE

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;             ┌───────────────────────────────────────────────╖
;             │      OUTPUT STATUS  (for troubleshooting)     ║
;             ╘═══════════════════════════════════════════════╝
;
; This status reporting is only for debugging.  It's not needed in the production units.
; Reporting by serial bit stream will be on PC4.  We'll start with a 1.5ms high pulse as a start bit, followed by a 1.5ms low
;   time, and then each 0 after that will be .5ms hi + 1ms lo, and each 1 will be 1ms hi + .5ms lo, so a bit starts every 1.5ms,
;   on a schedule.  There's an extra 1.5ms low time between bytes.  Interrupts will need to be turned off temporarily to avoid
;   jitter that would make it difficult to see the pattern repeating on an analog 'scope, as well as making sure short pulses
;   don't get too long.
; To make it easier to see where the start bit of a multi-byte report is with a dual-trace 'scope, PC3 (pin 14) is pulsed low.
;
;
;      low 1.5ms to make        Start     then  ┌────────── example 01001011, or $4B ──────────┐      ┌── start next byte
;      start bit visible─┐      1.5ms     1.5ms
;                        │       high      low    0     1     0     0     1     0     1     1           0     0
;             ───────┐   V    ┌────────┐        ┌─┐   ┌───┐ ┌─┐   ┌─┐   ┌───┐ ┌─┐   ┌───┐ ┌───┐       ┌─┐   ┌─┐   ┌─ . . .
; (PC4 pin 15)───────┴────────┘        └────────┘ └───┘   └─┘ └───┘ └───┘   └─┘ └───┘   └─┘   └───────┘ └───┘ └───┘
;
; (PC3 pin 14)────────────────┐        ┌─────────────────────────────────────────────────────────────────────────────────────────
; (for triggering)            └────────┘
;                                                                                               └──┬──┘
;                             └────────┬───────┘                                                   │
;                                      └─start bit                     1.5ms extra between bytes───┘
;
;
; Since it is not always desirable for the the status report to run every time OUTPUT_STATUS is encountered in the program, it
;   will look at PC5, pin 16, which has a passive pull-up.  If the switch to ground is open, it won't report.
; If you want it to keep reporting continually, you'll have to call it from a loop.
; Byte at RAM address REPORT_ARRAY is sent first.  Bytes are sent msb-first.
; To use OUTPUT_STATUS, put the bytes you want to output in REPORT_ARRAY, and put the number of bytes to report in REPORT_COUNT.
;   REPORT_COUNT will get decremented to 0 during the reporting, so the program must re-initialize it before each call.
; ══════════ NOTE !! If you call OUTPUT_STATUS repeatedly in a loop, you must re-init REPORT_COUNT every time! ══════════