67 lines
2.0 KiB
Plaintext
67 lines
2.0 KiB
Plaintext
; vim: set et:
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.program dap_swd
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.side_set 1 opt
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; Pin assignments:
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; - SWCLK is side-set pin 0
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; - SWDIO is OUT pin 0 and IN pin 0
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;
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; Autopush and autopull must be enabled, and the serial frame size is set by
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; configuring the push/pull threshold (32 bits). Shift should be left
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;
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; data is captured on the leading edge of each SWCLK pulse, and
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; transitions on the trailing edge, or some time before the first leading edge.
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start_thing:
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pull
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out y, 1
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out x, 31 side 0
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jmp !y start_swdo side 0
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start_swdi:
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loop_swdi:
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in pins, 1 side 1
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jmp x-- loop_swdi side 0
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end_swdi:
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push side 0
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jmp start_thing side 0
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start_swdo:
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loop_swdo:
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out pins, 1 side 0
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jmp x-- loop_swdo side 1
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end_swdo:
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jmp start_thing side 0
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% c-sdk {
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static inline void dap_swd_program_init(PIO pio, uint sm, uint offset,
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uint16_t freq, uint pin_swclk, uint pin_swdio) {
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pio_sm_config c = dap_swd_program_get_default_config(offset);
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sm_config_set_out_pins(&c, pin_swdio, 1);
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sm_config_set_in_pins(&c, pin_swdio);
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sm_config_set_sideset_pins(&c, pin_swclk);
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// (shift to left, autopush/pull, threshold=nbits)
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sm_config_set_out_shift(&c, false, true, 8); // shift left feature is broken???
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sm_config_set_in_shift(&c, false, true, 8);
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sm_config_set_clkdiv(&c, (float)clock_get_hz(clk_sys) / (2 * freq));
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// SWCLK is high, SWDIO is input (pull hi)
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pio_sm_set_pins_with_mask(pio, sm,
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(1u << pin_swclk),
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(1u << pin_swclk) | (1u << pin_swdio));
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pio_sm_set_pindirs_with_mask(pio, sm,
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(1u << pin_swclk) | (0u << pin_swdio),
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(1u << pin_swclk) | (1u << pin_swdio));
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pio_gpio_init(pio, pin_swclk);
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pio_gpio_init(pio, pin_swdio);
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// swd is synchronous, so bypass input synchroniser to reduce input delay.
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hw_set_bits(&pio->input_sync_bypass, 1u << pin_swdio);
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gpio_set_pulls(pin_swclk, false, true); // SWDIO is pulled up
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pio_sm_init(pio, sm, offset, &c);
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pio_sm_set_enabled(pio, sm, true);
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}
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%}
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