Add pio/ir_nec (#129)

Co-authored-by: martin <admin@crossleys.biz>
2021-10-26 22:16:15 +01:00
parent 09e34e7c1a
commit 1ec5e530b1
16 changed files with 632 additions and 0 deletions
--- a/pio/ir_nec/nec_transmit_library/nec_transmit.c
+++ b/pio/ir_nec/nec_transmit_library/nec_transmit.c
@@ -0,0 +1,97 @@
+/**
+ * Copyright (c) 2021 mjcross
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+
+// SDK types and declarations
+//
+#include "pico/stdlib.h"
+#include "hardware/pio.h"
+#include "hardware/clocks.h"    // for clock_get_hz()
+
+
+// declare the public API functions
+//
+#include "nec_transmit.h"
+
+
+// import the assembled PIO state machine programs
+//
+#include "nec_carrier_burst.pio.h"
+#include "nec_carrier_control.pio.h"
+
+
+// define the public API functions
+//
+
+// Claim an unused state machine on the specified PIO and configure it
+// to transmit NEC IR frames on the specificied GPIO pin.
+//
+// Returns: on success, the number of the carrier_control state machine
+// otherwise -1
+//
+int nec_tx_init(PIO pio, uint pin_num) {
+
+    // install the carrier_burst program in the PIO shared instruction space
+    //
+    uint carrier_burst_offset;
+    if (pio_can_add_program (pio, &nec_carrier_burst_program)) {
+        carrier_burst_offset = pio_add_program(pio, &nec_carrier_burst_program);
+    } else {
+        return -1;
+    }
+
+    // claim an unused state machine on this PIO
+    //
+    int carrier_burst_sm = pio_claim_unused_sm(pio, true);
+    if (carrier_burst_sm == -1) {
+        return -1;
+    }
+
+    // configure and enable the state machine
+    //
+    nec_carrier_burst_program_init(pio,
+                                   carrier_burst_sm,
+                                   carrier_burst_offset,
+                                   pin_num,
+                                   38.222e3);                   // 38.222 kHz carrier
+
+    // install the carrier_control program in the PIO shared instruction space
+    //
+    uint carrier_control_offset;
+    if (pio_can_add_program (pio, &nec_carrier_control_program)) {
+        carrier_control_offset = pio_add_program(pio, &nec_carrier_control_program);
+    } else {
+        return -1;
+    }
+
+    // claim an unused state machine on this PIO
+    //
+    int carrier_control_sm = pio_claim_unused_sm(pio, true);
+    if (carrier_control_sm == -1) {
+        return -1;
+    }
+
+    // configure and enable the state machine
+    //
+    nec_carrier_control_program_init(pio,
+                                     carrier_control_sm,
+                                     carrier_control_offset,
+                                     2 * (1 / 562.5e-6),        // 2 ticks per 562.5us carrier burst
+                                     32);                       // 32 bits per frame
+
+    return carrier_control_sm;
+}
+
+
+// Create a frame in `NEC` format from the provided 8-bit address and data
+//
+// Returns: a 32-bit encoded frame
+//
+uint32_t nec_encode_frame (uint8_t address, uint8_t data) {
+    // a normal 32-bit frame is encoded as address, inverted address, data, inverse data,
+    //
+    return address | (address ^ 0xff) << 8 | data << 16 | (data ^ 0xff) << 24;
+}