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comparison dac.pio @ 0:a55e39064a71

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First commit of code that compiles. Does nothing like it should but has cmake goo to wrap dat files
author Daniel O'Connor <darius@dons.net.au>
date Mon, 29 Mar 2021 13:48:34 +1030
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children 0d653f60dec8
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-1:000000000000 0:a55e39064a71
1 ;
2 ; Copyright (c) 2021 Raspberry Pi (Trading) Ltd.
3 ;
4 ; SPDX-License-Identifier: BSD-3-Clause
5 ;
6
7 .program dac
8
9 ; Sample bits using an external clock, and push groups of bits into the RX FIFO.
10 ; - IN pin 0 is the data pin
11 ; - IN pin 1 is the clock pin
12 ; - Autopush is enabled, threshold 8
13 ;
14 ; This program samples data with each rising clock edge (like mode 0 or mode 3
15 ; SPI). The data is actually sampled one system clock cycle after the rising
16 ; edge is observed, so a clock ratio of at least input_clk < clk_sys / 6 is
17 ; recommended for good sampling alignment.
18
19 wait 0 pin 1
20 wait 1 pin 1
21 in pins, 1
22
23 % c-sdk {
24 static inline void dac_program_init(PIO pio, uint sm, uint offset, uint pin) {
25 pio_sm_config c = dac_program_get_default_config(offset);
26
27 // Set the IN base pin to the provided `pin` parameter. This is the data
28 // pin, and the next-numbered GPIO is used as the clock pin.
29 sm_config_set_in_pins(&c, pin);
30 // Set the pin directions to input at the PIO
31 pio_sm_set_consecutive_pindirs(pio, sm, pin, 2, false);
32 // Connect these GPIOs to this PIO block
33 pio_gpio_init(pio, pin);
34 pio_gpio_init(pio, pin + 1);
35
36 // Shifting to left matches the customary MSB-first ordering of SPI.
37 sm_config_set_in_shift(
38 &c,
39 false, // Shift-to-right = false (i.e. shift to left)
40 true, // Autopush enabled
41 8 // Autopush threshold = 8
42 );
43
44 // We only receive, so disable the TX FIFO to make the RX FIFO deeper.
45 sm_config_set_fifo_join(&c, PIO_FIFO_JOIN_RX);
46
47 // Load our configuration, and start the program from the beginning
48 pio_sm_init(pio, sm, offset, &c);
49 pio_sm_set_enabled(pio, sm, true);
50 }
51 %}