79 lines
2.6 KiB
C
79 lines
2.6 KiB
C
/**
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* Copyright (c) 2021 mjcross
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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// SDK types and declarations
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//
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#include "pico/stdlib.h"
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#include "hardware/pio.h"
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#include "hardware/clocks.h" // for clock_get_hz()
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#include "nec_transmit.h"
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// import the assembled PIO state machine programs
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#include "nec_carrier_burst.pio.h"
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#include "nec_carrier_control.pio.h"
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// Claim an unused state machine on the specified PIO and configure it
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// to transmit NEC IR frames on the specificied GPIO pin.
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//
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// Returns: on success, the number of the carrier_control state machine
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// otherwise -1
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int nec_tx_init(PIO pio, uint pin_num) {
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// install the carrier_burst program in the PIO shared instruction space
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uint carrier_burst_offset;
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if (pio_can_add_program(pio, &nec_carrier_burst_program)) {
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carrier_burst_offset = pio_add_program(pio, &nec_carrier_burst_program);
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} else {
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return -1;
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}
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// claim an unused state machine on this PIO
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int carrier_burst_sm = pio_claim_unused_sm(pio, true);
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if (carrier_burst_sm == -1) {
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return -1;
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}
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// configure and enable the state machine
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nec_carrier_burst_program_init(pio,
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carrier_burst_sm,
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carrier_burst_offset,
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pin_num,
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38.222e3); // 38.222 kHz carrier
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// install the carrier_control program in the PIO shared instruction space
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uint carrier_control_offset;
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if (pio_can_add_program(pio, &nec_carrier_control_program)) {
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carrier_control_offset = pio_add_program(pio, &nec_carrier_control_program);
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} else {
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return -1;
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}
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// claim an unused state machine on this PIO
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int carrier_control_sm = pio_claim_unused_sm(pio, true);
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if (carrier_control_sm == -1) {
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return -1;
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}
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// configure and enable the state machine
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nec_carrier_control_program_init(pio,
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carrier_control_sm,
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carrier_control_offset,
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2 * (1 / 562.5e-6f), // 2 ticks per 562.5us carrier burst
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32); // 32 bits per frame
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return carrier_control_sm;
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}
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// Create a frame in `NEC` format from the provided 8-bit address and data
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//
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// Returns: a 32-bit encoded frame
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uint32_t nec_encode_frame(uint8_t address, uint8_t data) {
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// a normal 32-bit frame is encoded as address, inverted address, data, inverse data,
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return address | (address ^ 0xff) << 8 | data << 16 | (data ^ 0xff) << 24;
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}
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