ELM327 BLE verified in the car: service FFF0, FFF1 notify/write, ELM327 v2.1

Scanner log saved in 11-BLE-Scanner/results; CLAUDE.md updated with the adapter's GATT layout, replies and supported PIDs 01-20. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-23 14:21:44 +02:00
1 parent 8a84b42a3b
commit 0bd6aef6b5
@@ -0,0 +1,121 @@
+===== Inspect 61:69:aa:93:64:c9 (t=154s since boot) =====
+(no name)
+connect failed, error 13
+
+===== Scan list (t=9s since boot) =====
+d8:a7:77:62:cf:2b  -87 dBm  (no name)  [not connectable]
+6a:0b:59:2f:28:34  -78 dBm  (no name)
+02:04:bd:fc:cf:71  -88 dBm  (no name)  [not connectable]
+1e:f4:be:9f:3b:ec  -81 dBm  (no name)  [not connectable]
+48:db:b1:48:1c:ba  -92 dBm  (no name)
+71:e4:11:0c:69:31  -92 dBm  (no name)
+d7:03:e0:21:ae:2c  -82 dBm  (no name)  [not connectable]
+c8:49:09:05:72:65  -92 dBm  (no name)  [not connectable]
+50:ed:64:42:4e:1f  -93 dBm  (no name)  [not connectable]
+
+===== Inspect 71:e4:11:0c:69:31 (t=9s since boot) =====
+(no name)  -92 dBm
+
+SVC 0x1800
+  0x2a00  [R]
+  0x2a01  [R]
+
+SVC 0x1801
+  0x2a05  [I]
+
+SVC 0x180a
+  0x2a29  [R]
+  0x2a24  [R]
+
+SVC d0611e78-bbb4-4591-a5f8-487910ae4366
+  8667556c-9a37-4c91-84ed-54ee27d90049  [W N]
+
+SVC 9fa480e0-4967-4542-9390-d343dc5d04ae
+  af0badb1-5b99-43cd-917a-a77bc549e3cc  [W N]
+
+SVC 0x180f
+  0x2a19  [R N]
+
+SVC 0x1805
+  0x2a2b  [R N]
+  0x2a0f  [R]
+
+SVC 7905f431-b5ce-4e99-a40f-4b1e122d00d0
+  69d1d8f3-45e1-49a8-9821-9bbdfdaad9d9  [W]
+  9fbf120d-6301-42d9-8c58-25e699a21dbd  [N]
+  22eac6e9-24d6-4bb5-be44-b36ace7c7bfb  [N]
+
+SVC 89d3502b-0f36-433a-8ef4-c502ad55f8dc
+  9b3c81d8-57b1-4a8a-b8df-0e56f7ca51c2  [W N]
+  2f7cabce-808d-411f-9a0c-bb92ba96c102  [W N]
+  c6b2f38c-23ab-46d8-a6ab-a3a870bbd5d7  [R W]
+
+ELM candidate:
+  write  8667556c-9a37-4c91-84ed-54ee27d90049
+  notify 8667556c-9a37-4c91-84ed-54ee27d90049
+
+===== Scan list (t=43s since boot) =====
+be:67:00:63:4a:bb  -69 dBm  ELK-BLEDOM0B
+57:d8:bc:03:00:d2  -86 dBm  (no name)
+11:23:d0:d0:94:76  -87 dBm  (no name)  [not connectable]
+b8:ab:62:f5:df:63  -74 dBm  BlackVue970X-EA0D41
+58:4b:32:d8:a0:00  -59 dBm  (no name)  svc: 0xfd5a
+5f:20:5f:9e:52:29  -97 dBm  (no name)  [not connectable]
+5c:a0:49:f2:3d:63  -93 dBm  (no name)  [not connectable]
+e3:8d:69:a0:80:9d  -90 dBm  (no name)
+5c:13:59:55:ef:8e  -61 dBm  (no name)  svc: 0xfd5a
+6f:9a:f3:43:9e:69  -93 dBm  (no name)
+65:03:4a:ef:35:58  -59 dBm  (no name)  svc: 0xfd5a
+c6:f4:05:9e:ef:46  -95 dBm  (no name)  [not connectable]
+1c:a1:35:69:8d:c5  -77 dBm  OBDII  [OBD?]  svc: 0xfff0
+74:64:f9:df:4c:8e  -69 dBm  (no name)  svc: 0xfd69
+53:61:36:06:da:f6  -66 dBm  (no name)  svc: 0xfd69
+
+===== Inspect 1c:a1:35:69:8d:c5 (t=43s since boot) =====
+OBDII  -77 dBm
+
+SVC 0x1800
+  0x2a00  [R]
+
+SVC 0x1801
+  0x2a05  [I]
+
+SVC 0xfff0
+  0xfff1  [W WnR N]
+  0xfff2  [W WnR]
+
+ELM candidate:
+  write  0xfff1
+  notify 0xfff1
+
+===== ELM test 1c:a1:35:69:8d:c5 (t=50s since boot) =====
+> ATZ  (reset)
+ATZ
+ELM327 v2.1
+> ATE0  (echo off)
+ATE0
+OK
+> ATI  (version)
+ELM327 v2.1
+> ATRV  (battery voltage)
+12.9V
+> 0100  (supported PIDs (needs ignition on))
+41 00 BE 3E A8 13
+
+===== Scan list (saved by button) (t=54s since boot) =====
+be:67:00:63:4a:bb  -69 dBm  ELK-BLEDOM0B
+57:d8:bc:03:00:d2  -87 dBm  (no name)
+11:23:d0:d0:94:76  -87 dBm  (no name)  [not connectable]
+b8:ab:62:f5:df:63  -71 dBm  BlackVue970X-EA0D41
+58:4b:32:d8:a0:00  -59 dBm  (no name)  svc: 0xfd5a
+5f:20:5f:9e:52:29  -95 dBm  (no name)  [not connectable]
+5c:a0:49:f2:3d:63  -93 dBm  (no name)  [not connectable]
+e3:8d:69:a0:80:9d  -90 dBm  (no name)
+5c:13:59:55:ef:8e  -61 dBm  (no name)  svc: 0xfd5a
+6f:9a:f3:43:9e:69  -93 dBm  (no name)
+65:03:4a:ef:35:58  -59 dBm  (no name)  svc: 0xfd5a
+c6:f4:05:9e:ef:46  -95 dBm  (no name)  [not connectable]
+1c:a1:35:69:8d:c5  -81 dBm  OBDII  [OBD?]  svc: 0xfff0
+74:64:f9:df:4c:8e  -69 dBm  (no name)  svc: 0xfd69
+53:61:36:06:da:f6  -66 dBm  (no name)  svc: 0xfd69
+
@@ -95,7 +95,12 @@ Re-flash it with Flash Download Tool: ESP32-S3, `1.85_demo.bin` @ 0x0.

 ## OBD adapter (user's)
 AliExpress "ELM327 Mini V2.1 Bluetooth OBD **Dual Mode** 5.1" — dual mode = Bluetooth Classic SPP **and BLE**, so the ESP32-S3 should be able to connect directly over BLE (no bridge ESP32).
-Cheap dual-mode clones typically expose BLE service `FFF0` (notify `FFF1`, write `FFF2`) — **not yet verified** on this adapter; use `11-BLE-Scanner` in the car (results in its flash log). Adapter is powered from the car's OBD port (pin 16, 12 V).
+**Verified in the car (2026-10-23, `11-BLE-Scanner`, log in `11-BLE-Scanner/results/2026-10-23_car_test.txt`):**
+- BLE name **`OBDII`**, MAC `1c:a1:35:69:8d:c5`, advertises service **`0xFFF0`**. Characteristics: **`FFF1` [W, WnR, Notify]**, **`FFF2` [W, WnR]**.
+  Working setup: subscribe to notifications on `FFF1`, write commands (`"...␍"`) to `FFF1` (write without response) — `FFF2` is the usual write characteristic on such clones and should work too.
+- Replies: `ATZ` → `ELM327 v2.1` (echo on by default → send `ATE0`), `ATRV` → `12.9V`, `0100` → `41 00 BE 3E A8 13`.
+- **Supported PIDs 01–20** (from `BE 3E A8 13`): 01 monitor status, 03 fuel system, 04 engine load, 05 coolant temp, 06/07 fuel trim B1, **0B intake manifold pressure (MAP)**, **0C RPM**, **0D speed**, 0E timing advance, 0F intake air temp, 11 throttle, 13 O2 sensors, 15 O2 sensor 2, 1C OBD standard, 1F run time, 20 → more PIDs in 21–40. **No 10 (MAF)** → speed-density engine.
+- Adapter is powered from the car's OBD port (pin 16, 12 V).

 ## Gotchas / observations
 - **LVGL 8 GIF bug (patched locally, only relevant if LVGL 8 is used again):** LVGL 8.3.11 `gifdec.c` (`gd_open_gif`) filled the canvas *opaque* with the GIF's background color. GIFs with a transparent background (e.g. `loligod.gif`, bg = RGB 28,29,49) showed that dark gray except where "restore to background" frames had cleared to transparent (→ screen black). **Patched** in the vendor copy `2-Program Example/Demo_Arduino/library/lvgl/src/extra/libs/gif/gifdec.c`: initial canvas alpha 0x00 (marked `LOCAL PATCH`). Re-apply if LVGL is ever replaced/upgraded.