Laser Ranger 8-ch × mBlock 5 (Makeblock edition)
The Makeblock edition of the Laser Ranger 8-ch plugs into an RJ25 port on mBot, Ranger, Orion or MegaPi and is read with the MBC Pro Sensors extension v2 blocks. Installation and usable ports per board: Makeblock extension.
SPIKEEV3Arduino I2CmBlockMATRIXmicro:bit
Wiring
Sensor → mBot adapter → RJ25 port on the board (S1 = host TX, S2 = host RX). UART 38400 8N1.
Reporter blocks
| Block | Returns | Id | Meaning |
|---|---|---|---|
| Ranger 8 port [port] nearest distance cm | 0~120 cm | 01 |
smallest of the 8 distances, 0~120 cm (a failed sensor counts as 120); 120 = nothing around |
| Ranger 8 port [port] nearest direction | -8~+8 | 02 |
direction of the nearest object: −7 (left) to +7 (right), 0 = straight ahead, negative = left; ±8 = nothing around (keeps the last side) |
| Ranger 8 port [port] farthest distance cm | 0~120 cm | 03 |
largest of the 8 distances, 0~120 cm (a failed sensor always reads 120 and looks 'farthest') |
| Ranger 8 port [port] farthest direction | -7~+7 | 04 |
direction of the most open side: −7 to +7, 0 = straight ahead, negative = left; 0 when all 8 read 120 |
| Ranger 8 port [port] front distance cm | 0~120 cm | 05 |
average of sensors 4 and 5 (both facing forward), 0~120 cm; EV3 mode 3 and SPIKE mode 6 carry the same thing in mm; 0x22 'C' is min(4, 5), not the average (see 10) |
| Ranger 8 port [port] nearest distance mm | 0~1200 mm | 06 |
smallest of the 8 mm readings, 0~1200 (failed sensor counts as 1200); 1200 = nothing around |
| Ranger 8 port [port] init bitmap | 0~255 bit | 07 |
bit0 = sensor 1 (left) … bit7 = sensor 8; 1 = initialised at power-on (8 sensors take |
| Ranger 8 port [port] fault bitmap | 0~255 bit | 08 |
bit0 = sensor 1 … bit7 = sensor 8; 1 = currently failing (I2C error or no update for 200 ms); its distance reads 120 / 1200 |
| Ranger 8 port [port] front distance mm | 0~1200 mm | 09 |
average of sensors 4 and 5 (the two facing forward), 0~1200 mm; 1200 = nothing ahead. cm version is 05 |
| Ranger 8 port [port] sensor [1~8] distance cm | 0~120 cm | 10~17 |
distance of each sensor 1 |
| Ranger 8 port [port] sensor [1~8] distance mm | 0~1200 mm | 18~1F |
distance of each sensor 1 |
Command blocks
| Block | Id | Meaning |
|---|---|---|
| Ranger 8 port [port] update all values | FD |
reads the whole value table into a cache (FD pack-all); reporter blocks within the next 10 ms use the cache instead of asking one by one |
Status blocks
The extension exposes each F3 bit as a boolean block:
| bit | Name | Meaning |
|---|---|---|
| b0 | ready (ready) |
1 once all 8 sensors are initialised ( |
| b1 | any sensor failed (fault) |
1 if any sensor failed to initialise, has an I2C error or no update for 200 ms (08 ≠ 0 or 07 ≠ 255) |
Packet format (for your own decoder)
| Action | Format |
|---|---|
| Read one value | 主機送 [編號] → 回 [值低][值高][編號^值低^值高] |
| Write command | 寫入命令 E0~EE：收齊參數後回 [00][00][編號] 再執行；20 ms 內沒收齊就丟棄 |
| Unknown id | [00][80][編號^0x80]（= -32768） |
| Pack all (FD) | Send [FD] → reply [AA][19][25 × int16 LE][xor], xor = AA ^ N ^ all data bytes; content = this value table in ascending id order (shared ids and commands excluded). The extension fetches it once and serves blocks from a 10 ms cache. |
| Shared ids | F0 device ID, F1 protocol version, F2 firmware version, F3 status flags |
Sources and assumptions
Generated by _build/gen-reference.mjs from _build/protocol/tof8.json (single source of truth, transcribed from the 2026-10-21 protocol decisions).
- 正前方 mm（EV3 模式 3、SPIKE 模式 6 v[1]）在定案 §5 沒有獨立 I2C 編號 → 掛在 05 正前方 cm 底下，用 scale:mm 標示，不自己加編號。
- 0x22（使用者 2026-10-21 最終定案）：只用一個位址，R~K 由左到右 7 個 cm：第 1、2、3 顆、min(第 4, 第 5)、第 6、7、8 顆；11、12 不放資料；最近距離／方向由主機自己比較。此排法只用在 0x22，EV3／SPIKE不動。
- SPIKE：0/5/7/9 鎖住，1、2、3、4、8 維持不動；模式 6 改 [最近 mm, 正前方 mm, 最近方向 −8
+8]（原本 = 第 27 顆兩兩合併）；模式 8 v[0] 改 ID|hw[0]<<8。 - 最空曠方向 04 範圍 −7~+7（maxDirection 永遠不會是 0／16，盤點 INO:1086-1088）；最近方向 02 ±8 = 沒目標、沿用上次偏向側，開機預設 −8。
- 沒有寫入命令；F8 換位址／EF 重開機用共用的。
- 主對話 2026-10-21：補 09 正前方 mm（定案 §5 只有 05 正前方 cm，但 EV3 模式 3、SPIKE 模式 6 都送 mm，I2C／mBlock 應有同一個值）。
- Block wording follows the v2.0.0 extension generator
build_mext.js; this page is generated from the same JSON.