From 65f33acaa2b8b758306e9a5ef5faaa11a43679df Mon Sep 17 00:00:00 2001
From: "Christian W. Zuckschwerdt" <christian@zuckschwerdt.org>
Date: Thu, 6 Sep 2018 11:29:43 +0200
Subject: [PATCH] Clean up Acurite 986

---
 src/devices/acurite.c | 23 ++++++++---------------
 1 file changed, 8 insertions(+), 15 deletions(-)

diff --git a/src/devices/acurite.c b/src/devices/acurite.c
index 4eab92ae..ecb88764 100644
--- a/src/devices/acurite.c
+++ b/src/devices/acurite.c
@@ -792,7 +792,7 @@ static int acurite_txr_callback(bitbuffer_t *bitbuf) {
  */
 
 static int acurite_986_callback(bitbuffer_t *bitbuf) {
-    int browlen;
+    int const browlen = 5;
     uint8_t *bb, sensor_num, status, crc, crcc;
     uint8_t br[8];
     int8_t tempf; // Raw Temp is 8 bit signed Fahrenheit
@@ -806,8 +806,6 @@ static int acurite_986_callback(bitbuffer_t *bitbuf) {
     local_time_str(0, time_str);
 
     for (uint16_t brow = 0; brow < bitbuf->num_rows; ++brow) {
-	browlen = (bitbuf->bits_per_row[brow] + 7)/8;
-	bb = bitbuf->bb[brow];
 
 	if (debug_output > 1)
 	    fprintf(stderr,"acurite_986: row %d bits %d, bytes %d \n", brow, bitbuf->bits_per_row[brow], browlen);
@@ -818,6 +816,7 @@ static int acurite_986_callback(bitbuffer_t *bitbuf) {
 		fprintf(stderr,"acurite_986: skipping wrong len\n");
 	    continue;
 	}
+	bb = bitbuf->bb[brow];
 
 	// Reduce false positives
 	// may eliminate these with a better PPM (precise?) demod.
@@ -826,11 +825,6 @@ static int acurite_986_callback(bitbuffer_t *bitbuf) {
 	    continue;
 	}
 
-	// There will be 1 extra false zero bit added by the demod.
-	// this forces an extra zero byte to be added
-	if (browlen > 5 && bb[browlen - 1] == 0)
-	    browlen--;
-
 	// Reverse the bits, msg sent LSB first
 	for (uint8_t i = 0; i < browlen; i++)
 	    br[i] = reverse8(bb[i]);
@@ -1173,21 +1167,20 @@ r_device acurite_txr = {
  *
  * Temperature only, Pulse Position
  *
- * 4 x 400 sample (150 uS) start/sync pulses
- * 40 (42) 50 (20 uS)  (sample data pulses)
- * short gap approx 130 samples
- * long gap approx 220 samples
- *
+ * A preamble: 2x of 216 us pulse + 276 us gap, 4x of 1600 us pulse + 1560 us gap
+ * 39 bits of data: 220 us pulses with short gap of 520 us or long gap of 880 us
+ * A transmission consists of two packets that run into each other.
+ * There should be 40 bits of data though. But the last bit can't be detected.
  */
 r_device acurite_986 = {
     .name           = "Acurite 986 Refrigerator / Freezer Thermometer",
     .modulation     = OOK_PULSE_PPM_RAW,
-    .short_limit    = 720,   // Threshold between short and long gap
+    .short_limit    = 720,   // Threshold between short 520 us and long 880 us gap
     .long_limit     = 1280,
     .reset_limit    = 4000,
     .json_callback  = &acurite_986_callback,
     .disabled       = 0,
-    .demod_arg      = 2,
+    .demod_arg      = 0,     // not used
 };
 
 /*