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Clean up Oregon Scientific SL109H
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@zuckschwerdt
zuckschwerdt committed Apr 8, 2019
1 parent 0974aca commit c03ce14
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Showing 3 changed files with 88 additions and 122 deletions.
7 changes: 7 additions & 0 deletions include/util.h
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Expand Up @@ -159,4 +159,11 @@ uint8_t xor_bytes(uint8_t const message[], unsigned num_bytes);
/// @return summation value
int add_bytes(uint8_t const message[], unsigned num_bytes);

/// Compute Addition of a number of nibbles (byte wise).
///
/// @param message bytes (of two nibbles) of message data
/// @param num_bytes number of bytes to sum
/// @return summation value
int add_nibbles(uint8_t const message[], unsigned num_bytes);

#endif /* INCLUDE_UTIL_H_ */
194 changes: 72 additions & 122 deletions src/devices/oregon_scientific_sl109h.c
View file
@@ -1,133 +1,83 @@
//some hints from http://www.osengr.org/WxShield/Downloads/OregonScientific-RF-Protocols-II.pdf
/** @file
Oregon Scientific SL109H decoder.
*/
/**
Oregon Scientific SL109H decoder.
#include "decoder.h"

#define SL109H_MESSAGE_LENGTH 38
#define CHECKSUM_BYTE_COUNT 4
#define CHECKSUM_START_POSITION 6
#define HUMIDITY_START_POSITION 6
#define HUMIDITY_BIT_COUNT 8
#define TEMPERATURE_START_POSITION 14
#define TEMPERATURE_BIT_COUNT 12
#define ID_START_POSITION 30

static uint8_t calculate_humidity(bitbuffer_t *bitbuffer, unsigned row_index)
{
int units_digit, tens_digit;

uint8_t out[1] = {0};
bitbuffer_extract_bytes(bitbuffer, row_index, HUMIDITY_START_POSITION, out, HUMIDITY_BIT_COUNT);

units_digit = out[0] & 0x0f;

tens_digit = (out[0] & 0xf0) >> 4;

return 10 * tens_digit + units_digit;
}

static int calculate_centigrade_decidegrees(bitbuffer_t *bitbuffer, unsigned row_index)
{
unsigned int decidegrees = 0;

uint8_t out[2] = {0};
bitbuffer_extract_bytes(bitbuffer, row_index, TEMPERATURE_START_POSITION, out, TEMPERATURE_BIT_COUNT);

if(out[0] & 0x80) decidegrees = (~decidegrees << TEMPERATURE_BIT_COUNT);

decidegrees |= (out[0] << 4) | ((out[1] & 0xf0) >> 4);

return decidegrees;
}

static uint8_t get_channel_bits(uint8_t first_byte)
{
return (first_byte & 0x0c) >> 2;
}
static int calculate_channel(uint8_t channel_bits)
{
return (channel_bits % 3) ? channel_bits : 3;
}

//rolling code: changes when thermometer reset button is pushed/battery is changed
static uint8_t get_id(bitbuffer_t *bitbuffer, unsigned row_index)
{
uint8_t out[1] = {0};
bitbuffer_extract_bytes(bitbuffer, row_index, ID_START_POSITION, out, SL109H_MESSAGE_LENGTH - ID_START_POSITION);

return out[0];
}
Data layout (bits):
//there may be more specific information here; not currently certain what information is encoded here
static int get_status(uint8_t fourth_byte)
{
return (fourth_byte & 0x3C) >> 2;
}
AAAA CC HHHH HHHH TTTT TTTT TTTT SSSS IIII IIII
static int calculate_checksum(r_device *decoder, bitbuffer_t *bitbuffer, unsigned row_index, int channel)
{
uint8_t calculated_checksum, actual_checksum;
uint8_t sum = 0;
int actual_expected_comparison;

uint8_t out[CHECKSUM_BYTE_COUNT] = {0};
bitbuffer_extract_bytes(bitbuffer, row_index, CHECKSUM_START_POSITION, out, SL109H_MESSAGE_LENGTH - CHECKSUM_START_POSITION);

for(int i = 0; i < CHECKSUM_BYTE_COUNT; i++) sum += (out[i] & 0x0f) + (out[i] >> 4);

calculated_checksum = ((sum + channel) % 16);
actual_checksum = bitbuffer->bb[row_index][0] >> 4;
actual_expected_comparison = (calculated_checksum == actual_checksum);

if(decoder->verbose & !actual_expected_comparison) {
fprintf(stderr, "Checksum error in Oregon Scientific SL109H message. Expected: %01x Calculated: %01x\n", actual_checksum, calculated_checksum);
fprintf(stderr, "Message: ");
bitbuffer_print(bitbuffer);
}
- A: 4 bit checksum (add)
- C: 2 bit channel number
- H: 8 bit BCD humidity
- T: 12 bit signed temperature scaled by 10
- S: 4 bit status, unknown
- I: 8 bit a random id that is generated when the sensor starts
return actual_expected_comparison;
}
S.a. http://www.osengr.org/WxShield/Downloads/OregonScientific-RF-Protocols-II.pdf
*/

#include "decoder.h"

static int oregon_scientific_sl109h_callback(r_device *decoder, bitbuffer_t *bitbuffer)
{
data_t *data;
uint8_t *msg;
uint8_t channel_bits;
uint8_t b[5];

float temp_c;
uint8_t humidity;
uint8_t sum, chk;
int channel;
uint8_t id;
uint8_t humidity;
int temp_raw;
float temp_c;
int status;
uint8_t id;

for(int row_index = 0; row_index < bitbuffer->num_rows; row_index++) {
msg = bitbuffer->bb[row_index];
if (bitbuffer->bits_per_row[row_index] != 38) // expected length is 38 bit
continue;

channel_bits = get_channel_bits(msg[0]);
msg = bitbuffer->bb[row_index];
chk = msg[0] >> 4;

if( !((bitbuffer->bits_per_row[row_index] == SL109H_MESSAGE_LENGTH)
&& calculate_checksum(decoder, bitbuffer, row_index, channel_bits)) ) continue;
// align the channel "half nibble"
bitbuffer_extract_bytes(bitbuffer, row_index, 2, b, 36);
b[0] &= 0x3f;

sum = add_nibbles(b, 5) & 0xf;
if (sum != chk) {
if (decoder->verbose > 1)
bitbuffer_printf(bitbuffer, "Checksum error in Oregon Scientific SL109H message. Expected: %01x Calculated: %01x\n", chk, sum);
continue;
}

temp_c = calculate_centigrade_decidegrees(bitbuffer, row_index) / 10.0;
channel = b[0] >> 4;
channel = (channel % 3) ? channel : 3;

humidity = calculate_humidity(bitbuffer, row_index);
humidity = 10 * (b[0] & 0x0f) + (b[1] >> 4);

id = get_id(bitbuffer, row_index);
temp_raw = (int16_t)((b[1] & 0x0f) << 12) | (b[2] << 4); // uses sign-extend
temp_c = (temp_raw >> 4) * 0.1f;

channel = calculate_channel(channel_bits);
// there may be more specific information here; not currently certain what information is encoded here
status = (b[3] >> 4);

status = get_status(msg[3]);
// changes when thermometer reset button is pushed/battery is changed
id = ((b[3] & 0x0f) << 4) | (b[4] >> 4);

/* clang-format off */
data = data_make(
"model", "Model", DATA_STRING, _X("Oregon-SL109H","Oregon Scientific SL109H"),
"id", "Id", DATA_INT, id,
"channel", "Channel", DATA_INT, channel,
"temperature_C", "Celsius", DATA_FORMAT, "%.02f C", DATA_DOUBLE, temp_c,
"humidity", "Humidity", DATA_FORMAT, "%u %%", DATA_INT, humidity,
"status", "Status", DATA_INT, status,
"mic", "Integrity", DATA_STRING, "CHECKSUM",
NULL);
"model", "Model", DATA_STRING, _X("Oregon-SL109H","Oregon Scientific SL109H"),
"id", "Id", DATA_INT, id,
"channel", "Channel", DATA_INT, channel,
"temperature_C", "Celsius", DATA_FORMAT, "%.02f C", DATA_DOUBLE, temp_c,
"humidity", "Humidity", DATA_FORMAT, "%u %%", DATA_INT, humidity,
"status", "Status", DATA_INT, status,
"mic", "Integrity", DATA_STRING, "CHECKSUM",
NULL);
/* clang-format on */

decoder_output_data(decoder, data);
return 1;
}
Expand All @@ -136,24 +86,24 @@ static int oregon_scientific_sl109h_callback(r_device *decoder, bitbuffer_t *bit
}

static char *output_fields[] = {
"model",
"id",
"channel",
"status",
"temperature_C",
"humidity",
"mic",
NULL
"model",
"id",
"channel",
"status",
"temperature_C",
"humidity",
"mic",
NULL,
};

r_device oregon_scientific_sl109h = {
.name = "Oregon Scientific SL109H Remote Thermal Hygro Sensor",
.modulation = OOK_PULSE_PPM,
.short_width = 2000,
.long_width = 4000,
.gap_limit = 5000,
.reset_limit = 10000, // packet gap is 8900
.decode_fn = &oregon_scientific_sl109h_callback,
.disabled = 0,
.fields = output_fields
.name = "Oregon Scientific SL109H Remote Thermal Hygro Sensor",
.modulation = OOK_PULSE_PPM,
.short_width = 2000,
.long_width = 4000,
.gap_limit = 5000,
.reset_limit = 10000, // packet gap is 8900
.decode_fn = &oregon_scientific_sl109h_callback,
.disabled = 0,
.fields = output_fields,
};
9 changes: 9 additions & 0 deletions src/util.c
View file
Expand Up @@ -280,6 +280,15 @@ int add_bytes(uint8_t const message[], unsigned num_bytes)
return result;
}

int add_nibbles(uint8_t const message[], unsigned num_bytes)
{
int result = 0;
for (unsigned i = 0; i < num_bytes; ++i) {
result += (message[i] >> 4) + (message[i] & 0x0f);
}
return result;
}

// Unit testing
#ifdef _TEST
int main(int argc, char **argv) {
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