Add elksmart-comm for transceiving infrared codesHEADorigin/mastermaster

The receive functionality is quite unstable,
however useful enough for something that is officially unsupported.

The gadget is picky about cables,
but it has ridiculous reach when it works.

1 files changed, 695 insertions, 0 deletions

diff --git a/elksmart-comm.c b/elksmart-comm.c
new file mode 100644
index 0000000..a16b2f4
--- /dev/null
+++ b/elksmart-comm.c
@@ -0,0 +1,695 @@
+/*
+ * elksmart-comm.c: ELK Smart infrared dongle tool (for the 4th generation)
+ *
+ * Copyright (c) 2024, Přemysl Eric Janouch <p@janouch.name>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+ * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+#include "config.h"
+#undef PROGRAM_NAME
+#define PROGRAM_NAME "elksmart-comm"
+#include "liberty/liberty.c"
+
+#include <libusb.h>
+
+// --- Utilities ---------------------------------------------------------------
+
+/// Search for a device with given vendor and product ID.
+/// This is quite similar to libusb_open_device_with_vid_pid().
+static libusb_device_handle *
+find_device (int vendor, int product, int *error)
+{
+	libusb_device **list = NULL;
+	libusb_device_handle *handle = NULL;
+	int result = 0;
+
+	ssize_t len = libusb_get_device_list (NULL, &list);
+	if (len < 0)
+	{
+		result = len;
+		goto out;
+	}
+
+	for (ssize_t i = 0; i < len; i++)
+	{
+		libusb_device *device = list[i];
+		struct libusb_device_descriptor desc = {};
+		if ((result = libusb_get_device_descriptor (device, &desc)))
+			print_debug ("%s", libusb_strerror (result));
+		else if (desc.idVendor != vendor || desc.idProduct != product)
+			continue;
+		else if (!(result = libusb_open (device, &handle)))
+			break;
+	}
+
+	libusb_free_device_list (list, true);
+out:
+	if (error != NULL && result != 0)
+		*error = result;
+	return handle;
+}
+
+static void
+wait_ms (long ms)
+{
+	struct timespec ts = { ms / 1000, (ms % 1000) * 1000 * 1000 };
+	nanosleep (&ts, NULL);
+}
+
+static void
+dump_hex (const unsigned char *buf, size_t len)
+{
+	for (size_t i = 0; i < len; i++)
+		printf ("%02x", buf[i]);
+	printf ("\n");
+}
+
+static bool
+read_hex (const char *string, struct str *out)
+{
+	static const char *alphabet = "0123456789abcdef";
+	str_reset (out);
+	while (true)
+	{
+		while (*string && strchr (" \t\n\r\v\f", *string))
+			string++;
+		if (!*string)
+			return true;
+
+		const char *hi, *lo;
+		if (!(hi = strchr (alphabet, tolower_ascii (*string++))) || !*string
+		 || !(lo = strchr (alphabet, tolower_ascii (*string++))))
+			return false;
+
+		str_pack_u8 (out, (hi - alphabet) << 4 | (lo - alphabet));
+	}
+}
+
+// --- Coding ------------------------------------------------------------------
+
+// Values are in microseconds.
+struct pulse { unsigned on, off; };
+
+static bool
+pulse_equal (struct pulse a, struct pulse b)
+{
+	return a.on == b.on && a.off == b.off;
+}
+
+static size_t
+decode_learned_direct (const uint8_t *b, size_t b_len, struct pulse *pulses)
+{
+	size_t pulses_len = 0;
+	for (size_t i = 0; i < b_len; )
+	{
+		struct pulse *pulse = &pulses[pulses_len++];
+		while (b[i] == 0xff)
+		{
+			pulse->on += 4080;
+			if (++i == b_len)
+				return 0;
+		}
+		pulse->on += b[i++] * 16;
+
+		// Who cares, presumably it stays off.
+		if (i == b_len)
+			break;
+
+		while (b[i] == 0xff)
+		{
+			pulse->off += 4080;
+			if (++i == b_len)
+				return 0;
+		}
+		pulse->off += b[i++] * 16;
+	}
+	return pulses_len;
+}
+
+static struct pulse *
+decode_learned (const struct str *code, size_t *len, struct error **e)
+{
+	// This conveniently has an upper bound.
+	struct pulse *pulses = xcalloc (code->len, sizeof *pulses);
+	if (!(*len = decode_learned_direct
+		((const uint8_t *) code->str, code->len, pulses)))
+	{
+		error_set (e, "code ends unexpectedly");
+		free (pulses);
+		return NULL;
+	}
+	return pulses;
+}
+
+static struct pulse *
+encode_nec_byte (struct pulse *p, uint8_t byte)
+{
+	for (int i = 7; i >= 0; i--)
+		*p++ = (struct pulse)
+			{ .on = 550, .off = ((byte >> i) & 1) ? 1650 : 550 };
+	return p;
+}
+
+static struct pulse *
+encode_nec (const struct str *code, size_t *len, struct error **e)
+{
+	if (code->len % 2)
+	{
+		error_set (e, "NEC transmission format requires pairs");
+		return NULL;
+	}
+
+	// The timings seem to be rather tolerant.
+	*len = code->len / 2 * (1 /* leader */ + 32 + 1 /* stop */);
+	struct pulse *pulses = xcalloc (*len, sizeof *pulses), *p = pulses;
+	for (size_t i = 0; i < code->len; i += 2)
+	{
+		*p++ = (struct pulse) { .on = 8500, .off = 4250 };
+		p = encode_nec_byte (p, code->str[i + 0]);
+		p = encode_nec_byte (p, ~code->str[i + 0]);
+		p = encode_nec_byte (p, code->str[i + 1]);
+		p = encode_nec_byte (p, ~code->str[i + 1]);
+		*p++ = (struct pulse) { .on = 550, .off = 25000 };
+	}
+	return pulses;
+}
+
+static void
+compress_value (unsigned value, struct str *encoded)
+{
+	if (value <= 2032)
+	{
+		// We fix a minor problem in the original Ocrustar algorithm.
+		uint8_t v = value / 16. + .5;
+		str_pack_u8 (encoded, MAX (2, v));
+	}
+	else
+		do
+		{
+			uint8_t v = value & 0x7f;
+			if ((value >>= 7))
+				v |= 0x80;
+			str_pack_u8 (encoded, v);
+		} while (value);
+}
+
+static void
+compress_pulses (const struct pulse *pulses, size_t len, struct str *encoded)
+{
+	unsigned counts[len] = {};
+	for (size_t i = 0; i < len; i++)
+		for (size_t k = 0; k < len; k++)
+			if (pulse_equal (pulses[i], pulses[k]))
+				counts[i]++;
+
+	struct pulse p1 = {}, p2 = {};
+	size_t top1 = 0, top2 = 0;
+	for (size_t i = 0; i < len; i++)
+		if (counts[i] > counts[top1])
+			p1 = pulses[top1 = i];
+	for (size_t i = 0; i < len; i++)
+		if (counts[i] < counts[top1]
+		 && counts[i] > counts[top2])
+			p2 = pulses[top2 = i];
+		 else if (counts[top2] == counts[top1])
+			p2 = pulses[top2 = i];
+
+	// Although I haven't really tried it, something tells me that
+	// this will work even in the degenerated case of len <= 2.
+	// XXX: The receiver might not like multibyte values here,
+	//   Ocrustar also oddly replaces 0xff with 0xfe for these fields.
+	compress_value (p2.on, encoded);
+	compress_value (p2.off, encoded);
+	compress_value (p1.on, encoded);
+	compress_value (p1.off, encoded);
+	str_pack_u8 (encoded, -1);
+	str_pack_u8 (encoded, -1);
+	str_pack_u8 (encoded, -1);
+
+	for (size_t i = 0; i < len; i++)
+	{
+		if (pulse_equal (pulses[i], p1))
+			str_pack_u8 (encoded, 0);
+		else if (pulse_equal (pulses[i], p2))
+			str_pack_u8 (encoded, 1);
+		else
+		{
+			compress_value (pulses[i].on, encoded);
+			compress_value (pulses[i].off, encoded);
+		}
+	}
+}
+
+// --- Device interaction ------------------------------------------------------
+
+enum
+{
+	USB_VENDOR_SMTCTL = 0x045c,
+
+	// 0x134 (EKX5S ~ 5s, 5th generation remote)
+	// 0x195 (EKX4S ~ 4s, 4th generation remote)
+	// 0x184 (international edition)
+	USB_PRODUCT_SMTCTL_SMART = 0x0195,
+
+	// There should only ever be one interface.
+	USB_INTERFACE = 0,
+};
+
+static uint8_t
+	c_transmit[] = { -1, -1, -1, -1 },
+	c_learn[]    = { -2, -2, -2, -2 },
+	c_stop[]     = { -3, -3, -3, -3 },
+	c_identify[] = { -4, -4, -4, -4 };
+
+static struct
+{
+	unsigned char endpoint_out;         ///< Outgoing endpoint
+	unsigned char endpoint_in;          ///< Incoming endpoint
+}
+g;
+
+static bool
+init_device_from_desc (struct libusb_config_descriptor *desc, struct error **e)
+{
+	// We're not being particuarly strict in here.
+	if (desc->bNumInterfaces != 1)
+		return error_set (e, "unexpected USB interface count");
+	if (desc->interface->num_altsetting != 1)
+		return error_set (e, "unexpected alternate setting count");
+
+	const struct libusb_interface_descriptor *asd = desc->interface->altsetting;
+	if (asd->bInterfaceClass != LIBUSB_CLASS_COMM)
+		return error_set (e, "unexpected USB interface class");
+	if (asd->bNumEndpoints != 2)
+		return error_set (e, "unexpected endpoint count");
+
+	bool have_out = false, have_in = false;
+	for (uint8_t i = 0; i < asd->bNumEndpoints; i++)
+	{
+		const struct libusb_endpoint_descriptor *epd = asd->endpoint + i;
+		if ((epd->bmAttributes & LIBUSB_TRANSFER_TYPE_MASK)
+			!= LIBUSB_ENDPOINT_TRANSFER_TYPE_BULK)
+			return error_set (e, "unexpected endpoint transfer type");
+
+		switch ((epd->bEndpointAddress & LIBUSB_ENDPOINT_DIR_MASK))
+		{
+		break; case LIBUSB_ENDPOINT_OUT:
+			have_out = true;
+			g.endpoint_out = epd->bEndpointAddress;
+		break; case LIBUSB_ENDPOINT_IN:
+			have_in = true;
+			g.endpoint_in = epd->bEndpointAddress;
+		}
+	}
+	if (!have_out || !have_in)
+		return error_set (e, "USB interface is not bidirectional");
+	return true;
+}
+
+static bool
+init_device (libusb_device_handle *device, struct error **e)
+{
+	struct libusb_config_descriptor *desc = NULL;
+	int result =
+		libusb_get_active_config_descriptor (libusb_get_device (device), &desc);
+	if (result)
+		return error_set (e, "%s", libusb_strerror (result));
+
+	bool ok = true;
+	if ((result = libusb_kernel_driver_active (device, USB_INTERFACE)) == 1)
+		ok = error_set (e, "device is claimed by a kernel driver");
+	else if (result)
+		ok = error_set (e, "%s", libusb_strerror (result));
+	else
+		ok = init_device_from_desc (desc, e);
+
+	libusb_free_config_descriptor (desc);
+	return ok;
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+static uint8_t
+mangle (uint8_t value)
+{
+	uint8_t reversed = 0;
+	for (int i = 0; i < 8; i++)
+	{
+		reversed = (reversed << 1) | (value & 1);
+		value >>= 1;
+	}
+	return ~reversed;
+}
+
+static uint8_t
+checksum (const uint8_t *b, size_t len)
+{
+	uint32_t sum = 0;
+	for (size_t i = 0; i < len; i++)
+		sum += b[i];
+	return mangle ((sum & 0xF0) | ((sum >> 8) & 0x0F));
+}
+
+static bool
+send_transmit (libusb_device_handle *device, unsigned long frequency,
+	const struct pulse *pulses, size_t pulses_len, struct error **e)
+{
+	if (g_debug_mode)
+		for (size_t i = 0; i < pulses_len; )
+		{
+			printf ("%u,%u", pulses[i].on, pulses[i].off);
+			putchar (++i == pulses_len ? '\n' : ',');
+		}
+
+	struct str compressed = str_make ();
+	compress_pulses (pulses, pulses_len, &compressed);
+
+	struct str message = str_make ();
+	str_append_data (&message, c_transmit, sizeof c_transmit);
+	frequency += 0x7ffff;
+	str_pack_u8 (&message, mangle (frequency >> 8));
+	str_pack_u8 (&message, mangle (frequency >> 16));
+	str_pack_u8 (&message, mangle (frequency));
+	str_pack_u8 (&message, mangle (compressed.len >> 8));
+	str_pack_u8 (&message, mangle (compressed.len));
+	str_append_str (&message, &compressed);
+	str_free (&compressed);
+
+	size_t i = 0;
+	uint8_t buffer[64];
+	bool ok = true;
+	while (i != message.len)
+	{
+		size_t chunk = MIN (62, message.len - i);
+		memcpy (buffer, message.str + i, chunk);
+		i += chunk;
+		if (chunk == 62)
+		{
+			buffer[chunk] = checksum (buffer, chunk);
+			chunk++;
+		}
+
+		int result = 0, len = 0;
+		if ((result = libusb_bulk_transfer (device, g.endpoint_out,
+			buffer, chunk, &len, 100)))
+		{
+			ok = error_set (e, "send: %s", libusb_strerror (result));
+			break;
+		}
+		wait_ms (2);
+	}
+	str_free (&message);
+	return ok;
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+static bool
+pulse_is_likely_leader (const struct pulse *p)
+{
+	return p->on >= 2048 && p->off >= 2048;
+}
+
+static void
+try_to_depulse (const struct str *code)
+{
+	size_t len = 0;
+	struct pulse *pulses = decode_learned (code, &len, NULL);
+	if (!pulses)
+		return;
+
+	struct pulse *p = pulses, *end = p + len;
+	while (p != end && pulse_is_likely_leader (p))
+	{
+		p++;
+		printf ("Attempted pulse decode:\n");
+
+		uint8_t bits = 0, nibble = 0;
+		for (; p != end && !pulse_is_likely_leader (p); p++)
+		{
+			nibble = nibble << 1 | (p->off > 2 * p->on);
+			if (++bits == 4)
+			{
+				putchar ("0123456789abcdef"[nibble]);
+				bits = nibble = 0;
+			}
+		}
+		putchar ('\n');
+	}
+	free (pulses);
+}
+
+static bool
+recv_learn (libusb_device_handle *device, struct str *data, struct error **e)
+{
+	uint8_t buffer[64] = {};
+	int result = 0, len = 0;
+	while ((result = libusb_bulk_transfer (device, g.endpoint_in,
+		buffer, sizeof buffer, &len, 100)))
+	{
+		if (result != LIBUSB_ERROR_TIMEOUT)
+			return error_set (e, "learn/recv: %s", libusb_strerror (result));
+		print_debug ("learn/recv: %s", libusb_strerror (result));
+	}
+	if (len < 6 || memcmp (buffer, c_learn, sizeof c_learn))
+		return error_set (e, "learn/recv: %s", "unexpected response");
+
+	// This field might only make sense for a later device,
+	// because it doesn't always correspond with how much data we receive.
+	// Nonetheless, it does match exactly often enough.
+	size_t size = buffer[4] << 8 | buffer[5];
+	print_debug ("learn: code size: %zu", size);
+
+	str_append_data (data, buffer + 6, len - 6);
+	dump_hex ((const unsigned char *) data->str, data->len);
+	while (data->len < size)
+	{
+		if (!(result = libusb_bulk_transfer (device, g.endpoint_in,
+			buffer, sizeof buffer, &len, 100)))
+		{
+			dump_hex (buffer, len);
+
+			str_append_data (data, buffer, len);
+			print_debug ("learn: received %d (have %zu of %zu)",
+				len, data->len, size);
+			continue;
+		}
+		if (result != LIBUSB_ERROR_TIMEOUT)
+			return error_set (e, "learn/recv: %s", libusb_strerror (result));
+
+		// The device seems to queue up its output with pauses.
+		print_debug ("learn/recv: %s", libusb_strerror (result));
+	}
+
+	// As far as I know, this doesn't do anything,
+	// and the device doesn't accept it while scanning infrared codes either.
+	if ((result = libusb_bulk_transfer (device, g.endpoint_out,
+		c_stop, sizeof c_stop, &len, 100)))
+		return error_set (e, "learn/send: %s", libusb_strerror (result));
+	return true;
+}
+
+static bool
+send_learn (libusb_device_handle *device, struct error **e)
+{
+	int result = 0, len = 0;
+	if ((result = libusb_bulk_transfer (device, g.endpoint_out,
+		c_learn, sizeof c_learn, &len, 100)))
+		return error_set (e, "learn/send: %s", libusb_strerror (result));
+
+	printf ("Reading remote control codes.\n");
+	printf ("Press a remote control button from less than a centimeter.\n");
+	printf ("The dongle may be unusable until it returns some data.\n");
+	// ... Resetting the device using libusb_reset_device() doesn't help then.
+	printf ("If the code fails to replay, retry the capture.\n");
+
+	struct str data = str_make ();
+	bool ok = recv_learn (device, &data, e);
+	if (ok)
+	{
+		printf ("Full command:\n");
+		dump_hex ((const unsigned char *) data.str, data.len);
+		try_to_depulse (&data);
+	}
+
+	str_free (&data);
+	return ok;
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+static bool
+send_identify (libusb_device_handle *device, struct error **e)
+{
+	uint8_t buffer[64] = {};
+	int result = 0, len = 0;
+	while (!(result = libusb_bulk_transfer (device, g.endpoint_in,
+		buffer, sizeof buffer, &len, 10)))
+		/* Flush buffers. */;
+
+	if ((result = libusb_bulk_transfer (device, g.endpoint_out,
+		c_identify, sizeof c_identify, &len, 100)))
+		return error_set (e, "identify/send: %s", libusb_strerror (result));
+	if ((result = libusb_bulk_transfer (device, g.endpoint_in,
+		buffer, sizeof buffer, &len, 100)))
+		return error_set (e, "identify/recv: %s", libusb_strerror (result));
+
+	// XXX: Sometimes, the device doesn't send any identification values.
+	if (len != 6 || memcmp (buffer, c_identify, sizeof c_identify)
+	 || buffer[4] != 0x70 || buffer[5] != 0x01)
+		return error_set (e, "device busy or not supported");
+
+#if 0
+	// My device does not respond to this request.
+	static uint8_t c_serial[] = { -5, -5, -5, -5 };
+	if ((result = libusb_bulk_transfer (device, g.endpoint_out,
+		c_serial, sizeof c_serial, &len, 100)))
+		return error_set (e, "serial/send: %s", libusb_strerror (result));
+	if ((result = libusb_bulk_transfer (device, g.endpoint_in,
+		buffer, sizeof buffer, &len, 100)))
+		return error_set (e, "serial/recv: %s", libusb_strerror (result));
+	if (len < (int) sizeof c_serial
+	 || memcmp (buffer, c_serial, sizeof c_serial))
+		return error_set (e, "serial retrieval failed");
+#endif
+	return true;
+}
+
+static bool
+run (libusb_device_handle *device, unsigned long frequency, bool nec,
+	char **codes, size_t codes_len, struct error **e)
+{
+	if (!send_identify (device, e))
+		return false;
+	if (!codes_len)
+		return send_learn (device, e);
+
+	struct str code = str_make ();
+	bool ok = true;
+	for (size_t i = 0; i < codes_len; i++)
+	{
+		if (!read_hex (codes[i], &code))
+		{
+			ok = error_set (e, "invalid hex string");
+			break;
+		}
+
+		size_t pulses_len = 0;
+		struct pulse *pulses = nec
+			? encode_nec (&code, &pulses_len, e)
+			: decode_learned (&code, &pulses_len, e);
+
+		ok = pulses && send_transmit (device, frequency, pulses, pulses_len, e);
+		free (pulses);
+		if (!ok)
+			break;
+
+		wait_ms (100);
+	}
+	str_free (&code);
+	return ok;
+}
+
+// --- Main --------------------------------------------------------------------
+
+int
+main (int argc, char *argv[])
+{
+	unsigned long frequency = 38000;
+	bool nec = false;
+	static const struct opt opts[] =
+	{
+		{ 'd', "debug", NULL, 0, "run in debug mode" },
+		{ 'f', "frequency", "HZ", 0, "frequency (38000 Hz by default)" },
+		{ 'n', "nec", NULL, 0, "use the NEC transmission format" },
+		{ 'h', "help", NULL, 0, "display this help and exit" },
+		{ 'V', "version", NULL, 0, "output version information and exit" },
+		{ 0, NULL, NULL, 0, NULL }
+	};
+
+	struct opt_handler oh = opt_handler_make (argc, argv, opts, "[COMMAND...]",
+		"Transmit or receive infrared commands.");
+
+	int c;
+	while ((c = opt_handler_get (&oh)) != -1)
+	switch (c)
+	{
+	case 'd':
+		g_debug_mode = true;
+		break;
+	case 'f':
+		if (!xstrtoul (&frequency, optarg, 10) || !frequency)
+			exit_fatal ("invalid frequency");
+		break;
+	case 'n':
+		nec = true;
+		break;
+	case 'h':
+		opt_handler_usage (&oh, stdout);
+		exit (EXIT_SUCCESS);
+	case 'V':
+		printf (PROGRAM_NAME " " PROGRAM_VERSION "\n");
+		exit (EXIT_SUCCESS);
+	default:
+		print_error ("wrong options");
+		opt_handler_usage (&oh, stderr);
+		exit (EXIT_FAILURE);
+	}
+
+	argc -= optind;
+	argv += optind;
+
+	opt_handler_free (&oh);
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+#if LIBUSB_API_VERSION >= 0x0100010A
+	const struct libusb_init_option option =
+	{
+		.option = LIBUSB_OPTION_LOG_LEVEL,
+		.value.ival = LIBUSB_LOG_LEVEL_DEBUG,
+	};
+	int result = libusb_init_context (NULL, &option, g_debug_mode);
+#else
+	int result = libusb_init (NULL);
+#endif
+	if (result)
+		exit_fatal ("libusb: %s", libusb_strerror (result));
+
+	libusb_device_handle *device =
+		find_device (USB_VENDOR_SMTCTL, USB_PRODUCT_SMTCTL_SMART, &result);
+	if (result)
+		exit_fatal ("couldn't open device: %s", libusb_strerror (result));
+	else if (!device)
+		exit_fatal ("no suitable device found");
+
+	struct error *e = NULL;
+	if (!init_device (device, &e))
+		exit_fatal ("%s", e->message);
+	if ((result = libusb_claim_interface (device, USB_INTERFACE)) == 1)
+		exit_fatal ("couldn't claim interface: %s", libusb_strerror (result));
+
+	if (!run (device, frequency, nec, argv, argc, &e))
+	{
+		print_error ("%s", e->message);
+		error_free (e);
+	}
+
+	if ((result = libusb_release_interface (device, USB_INTERFACE)) == 1)
+		exit_fatal ("couldn't release interface: %s", libusb_strerror (result));
+
+	libusb_close (device);
+	libusb_exit (NULL);
+	return 0;
+}