ArduinoHondaOBD

An arduino code that reads Honda OBD Protocol and translates it to ELM327 protocol. I use Torque app to read and display the data on my android phone (via bluetooth), and a LCD (2x6) to display it on my car's dashboard.

Please refer to the screenshots below.

Applications

• Datalogging
• Diagnostics
• Trip Computer
• Etc

Supports

• Honda ECU's before 2002

Files

• hobd_uni - unified code for ELM bluetooth and LCD display with other improvements.
• hobd_elm - implements Honda OBD to ELM OBD2 protocol (bluetooth) - not updated
• hobd_lcd - implements Honda OBD to LCD display - not updated
• UNI_wiring.png - Unified wiring diagram for arduino UNO (compatible)

Wiring for hobd_uni (Joined ELM and LCD codes)

Honda 3 Pin DLC           Arduino Uno
Gnd --------------------- Gnd
+12 --------------------- Vin
K-line ------------------ Pin12

HC-05 Bluetooth           Arduino Uno               
Rx ---------------------- Pin11
Tx ---------------------- Pin10

LCD 16x2                  Arduino Uno               
RS ---------------------- Pin9
Enable ------------------ Pin8
D4 ---------------------- Pin7
D5 ---------------------- Pin6
D6 ---------------------- Pin5
D7 ---------------------- Pin4
VO ---------------------- 10k Potentiometer (+5V to Gnd)

Piezo Buzzer              Arduino Uno               
(+) --------------------- Pin13
(-) --------------------- Gnd

Tact Switch               Arduino Uno               
(+) --------------------- Pin17 (A3)
(-) --------------------- Gnd

Voltage Divider           Arduino Uno               
+12V divider circuit ---- Pin14 (A0)
(680k ohms and 220k ohms)

Wiring for hobd_elm (Deprecated use hobd_uni)

Honda 3 Pin DLC           Arduino Uno
Gnd --------------------- Gnd
+12 --------------------- Vin
K-line ------------------ Pin12

HC-05 Bluetooth           Arduino Uno               
Rx ---------------------- Pin11
Tx ---------------------- Pin10

Wiring for hobd_lcd (Deprecated use hobd_uni)

Honda 3 Pin DLC           Arduino Uno
Gnd --------------------- Gnd
+12 --------------------- Vin
K-line ------------------ Pin12

LCD 16x2                  Arduino Uno               
RS ---------------------- Pin9
Enable ------------------ Pin8
D4 ---------------------- Pin7
D5 ---------------------- Pin6
D6 ---------------------- Pin5
D7 ---------------------- Pin4
VO ---------------------- 10k Potentiometer (+5V to Gnd)

Screenshots (LCD 16x2)

Screenshots (Andorid App TORQUE)

NOTES

• Added button for changing page (5ms) and changing ecu mode (3s).
• Added Fault codes reader @ lcd page 3
• Added LCD @ I2C support
  • #define LCD_i2c TRUE // Using LCD 16x2 I2C mode
• Added direct HOBD access API (ELM mode) used for undefined PIDs on OBD2
  • // direct honda PID access
  • // 1 byte access (21AA) // 21 = 1 byte, AA = address
  • // 2 bytes access (22AA) // 22 = 2 bytes, AA = address
  • // 4 byte access (24AA) // 24 = 4 bytes, AA = address
• Added direct Arduino Pin access API (ELM mode) used for keyless entry and other stuff
  • // set arduino pin (ATSAPNNX) // NN = pin, X = value (value is 1 or 0)
  • // get arduino pin (ATDAPNN) // NN = pin
• Tested on P2T ODB2 stock and P30 ODB1 chipped

TODO

• Add 128x64 LCD @ SPI support
• Add 20x4 LCD @ I2C support