diff --git a/README.md b/README.md
index 926350c4..8f3dac49 100644
--- a/README.md
+++ b/README.md
@@ -349,6 +349,7 @@ See [CONTRIBUTING.md](./docs/CONTRIBUTING.md).
[261] Geevon TX16-3 outdoor sensor
[262] Fine Offset Electronics WH46 air quality sensor
[263] Vevor Wireless Weather Station 7-in-1
+ [264] Arexx Multilogger IP-HA90, IP-TH78EXT, TSN-70E
* Disabled by default, use -R n or a conf file to enable
diff --git a/conf/rtl_433.example.conf b/conf/rtl_433.example.conf
index 4f134053..c392a8bf 100644
--- a/conf/rtl_433.example.conf
+++ b/conf/rtl_433.example.conf
@@ -490,6 +490,7 @@ convert si
protocol 261 # Geevon TX16-3 outdoor sensor
protocol 262 # Fine Offset Electronics WH46 air quality sensor
protocol 263 # Vevor Wireless Weather Station 7-in-1
+ protocol 264 # Arexx Multilogger IP-HA90, IP-TH78EXT, TSN-70E
## Flex devices (command line option "-X")
diff --git a/include/rtl_433_devices.h b/include/rtl_433_devices.h
index e6f2fb13..7bfd04e2 100644
--- a/include/rtl_433_devices.h
+++ b/include/rtl_433_devices.h
@@ -271,6 +271,7 @@
DECL(geevon) \
DECL(fineoffset_wh46) \
DECL(vevor_7in1) \
+ DECL(arexx_ml) \
/* Add new decoders here. */
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 94a8609d..37e06831 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -54,6 +54,7 @@ add_library(r_433 STATIC
devices/ant_antplus.c
devices/arad_ms_meter.c
devices/archos_tbh.c
+ devices/arexx_ml.c
devices/atech_ws308.c
devices/auriol_4ld5661.c
devices/auriol_aft77b2.c
diff --git a/src/devices/arexx_ml.c b/src/devices/arexx_ml.c
new file mode 100644
index 00000000..dc26c724
--- /dev/null
+++ b/src/devices/arexx_ml.c
@@ -0,0 +1,155 @@
+/** @file
+ Arexx Multilogger.
+
+ Copyright (C) 2023 Christian W. Zuckschwerdt <zany@triq.net>
+ Protocol analysis by MacH-21, TSN-70E by inonoob.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+*/
+
+#include "decoder.h"
+
+/**
+Arexx Multilogger.
+
+- Arexx IP-HA90 (MCP9808 sensor) s.a. #2388
+- Arexx IP-TH78EXT
+- Arexx TSN-70E (Sensirion SHT-10 sensor) s.a. #2482
+
+The IP-HA90 has a Microchip RFPIC12f675f at 433.92M and a Microchip MCP9808 temperature sensor.
+The TSN-70E has a Sensirion SHT-10 temperature and humidity and temperature sensor.
+
+FSK modulated with Manchester encoding, half-bit width is 208 us (2400bps MC).
+The sensors transmit approx. every 45 seconds alternating Temperature/Humidity.
+Polarity is inverted (IEEE MC) and the preamble+sync is aaaaaaaa55.
+
+Integrity check is done using CRC8 using poly=0x31 init=0x00.
+
+Example raw messages:
+
+ 55555555aa f8 71fe fedf f777 5b a4 ff
+ 55555555aa f8 71fe fedf f727 80 7f ff
+ 55555555aa f8 71fe fedf f6e7 8e 71 ff
+ 55555555aa f8 71fe fedf f69f b4 4b ff
+ 55555555aa f8 71fe fedf f66f c0 3f ff
+ 55555555aa f8 71fe fedf f63f 1b e4 ff
+ 55555555aa f8 71fe fedf f61f 38 c7 ff
+ 55555555aa f8 71fe fedf f607 67 98 ff
+ 55555555aa f8 71fe fedf f5f7 46 b9 ff
+ 55555555aa f8 71fe fedf f5d7 65 9a ff
+ 55555555aa f8 71fe fedf f5b7 00 ff ff
+ 55555555aa f8 71fe fedf f59f e1 1e ff
+ 55555555aa fa 15b2 e90f 6c ff faf7 7b1c e3
+ 55555555aa fa 14b2 f90e 51 ff faf7 7b1a e41
+ 55555555aa fa 14b2 f991 01 ff faf7 7b2a 401
+ 55555555aa fa 15b2 e678 0f ff faf7 7bf8 41
+
+Message format (preamble 5555aa then invert):
+
+ LEN:8h ID:<16h SENS:16h ?:8h8h CHK:8h CHKINV:8h 16x
+
+Message layout:
+
+ LL IIII SSSS UUUU XX YY
+
+- L : 8 bit: message length 7 or 5 (including length byte, excluding checksum)
+- I : 16 bit: ID, little-endian, even number = Temperature
+- S : 16 bit: raw sensor value
+- U : 16 bit: optional extra data, unknown
+- X : 8 bit: CRC, poly 0x31, init 0xc0
+- Y : 8 bit: inverted CRC check, only IP-HA90
+
+*/
+
+static int arexx_ml_decode(r_device *decoder, bitbuffer_t *bitbuffer)
+{
+ uint8_t const preamble[] = {0xaa, 0xaa, 0x55}; // 24 bits
+
+ if (bitbuffer->num_rows != 1) {
+ return DECODE_ABORT_EARLY; // we expect a single row
+ }
+ if (bitbuffer->bits_per_row[0] < 64 || bitbuffer->bits_per_row[1] > 130) {
+ return DECODE_ABORT_EARLY; // we expect around 88 to 104 bits
+ }
+ bitbuffer_invert(bitbuffer);
+
+ int msg_len = -1;
+ uint8_t b[9]; // allow up to 9 byte messages
+ for (int i = 0; i < bitbuffer->num_rows; ++i) {
+ unsigned pos = bitbuffer_search(bitbuffer, i, 0, preamble, 24);
+ pos += 24;
+
+ if (pos + 64 > bitbuffer->bits_per_row[i])
+ continue; // too short or not found
+
+ bitbuffer_extract_bytes(bitbuffer, i, pos, b, sizeof(b) * 8);
+ msg_len = b[0];
+ break;
+ }
+ if (msg_len <= 0) {
+ decoder_log(decoder, 2, __func__, "Couldn't find preamble");
+ return DECODE_FAIL_SANITY;
+ }
+
+ int chk = crc8le(b, msg_len, 0x31, 0x00);
+ if (chk != b[msg_len]) { // || (chk ^ b[msg_len + 1]) != 0) {
+ decoder_log(decoder, 2, __func__, "CRC fail");
+ return DECODE_FAIL_MIC;
+ }
+
+ // Extract data from buffer
+ int id = (b[2] << 8) | (b[1]); // little-endian
+ int sens_val = (b[3] << 8) | (b[4]); // big-endian?
+ int is_humi = id & 1; // even number: Temperature, odd number: Humidity
+
+ // MCP9808 Ambient Temperature Register "5-4":
+ int temp_alert = (sens_val >> 13) & 7;
+ int temp_raw = (int16_t)(sens_val << 3); // uses sign-extend
+ float temp_c = temp_raw / 128;
+
+ if (msg_len == 5) { // not sure if this is the proper check
+ // SHT10 Temperature
+ temp_c = sens_val * 0.01f - 40.0f; // offset actually varies by Vdd
+ }
+ // SHT10 Humidity
+ float humidity = -2.0468 + 0.0367 * sens_val - 1.5955E-6 * sens_val * sens_val;
+
+ /* clang-format off */
+ data_t *data = data_make(
+ "model", "", DATA_STRING, "Arexx-ML",
+ "id", "ID", DATA_FORMAT, "%04x", DATA_INT, id,
+ "temperature_C", "Temperature", DATA_COND, !is_humi, DATA_FORMAT, "%.2f C", DATA_DOUBLE, temp_c,
+ "temperature_alert", "Alert", DATA_COND, !is_humi, DATA_FORMAT, "%x", DATA_INT, temp_alert,
+ "humidity", "Humidity", DATA_COND, is_humi, DATA_FORMAT, "%.1f %%", DATA_DOUBLE, humidity,
+ "sensor_raw", "Sensor Raw", DATA_FORMAT, "%04x", DATA_INT, sens_val,
+ "mic", "Integrity", DATA_STRING, "CRC",
+ NULL);
+ /* clang-format on */
+
+ decoder_output_data(decoder, data);
+ return 1;
+}
+
+static char const *const arexx_ml_output_fields[] = {
+ "model",
+ "id",
+ "temperature_C",
+ "temperature_alert",
+ "humidity",
+ "sensor_raw",
+ "mic",
+ NULL,
+};
+
+r_device const arexx_ml = {
+ .name = "Arexx Multilogger IP-HA90, IP-TH78EXT, TSN-70E",
+ .modulation = FSK_PULSE_MANCHESTER_ZEROBIT,
+ .short_width = 208, // 2400bps MC
+ .long_width = 208, // not used
+ .reset_limit = 450,
+ .decode_fn = &arexx_ml_decode,
+ .fields = arexx_ml_output_fields,
+};