# 89c52 variable baud rate

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#### imranahmed

Please let know that can we set desired baud rate in 89c52 uC.
I want to set baud rate 8129.
Another question is that if system is design on 8129 baud rate so
can we communicate with 9600 or 4800 baud rates or its necessary
to communicate on 8129 baud rate?

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#### ark5230

Is there some specific reason for odd baud rate !!

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#### imranahmed

In General Motor car they use OBD-I protocol actually not protocol its Assembly Line Diagnostic Link (ALDL).
I am making a project for communicating data to Engine Control unit of my Daewoo Racer 1993 model.

#### tpetar

You dont need uC for ALDL interface.

You need OBD 1.5 its also called GM ALDL interface. OBD1 want work, you must use OBD1.5, and definitely you dont need this exibitions with uC.

Save 89S52 for some alarm circuit or some other things.

imranahmed

### imranahmed

Points: 2

#### imranahmed

Your posted picture of MAX232 ALDL interface will work on my daewoo racer car model 1993 and it has 12 pin connector, attached,
:grin:

#### Attachments

• aldl.bmp
2.3 MB · Views: 11
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#### tpetar

Also check this:

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You can search over Internet, I had fun with OBD earlier. :wink:

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One more ALDL circuit:

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http://en.wikipedia.org/wiki/On-board_diagnostics

OBD-1.5

OBD 1.5 refers to a partial implementation of OBD-II which General Motors used on some vehicles in 1994, 1995, & 1996. (GM did not use the term OBD 1.5 in the documentation for these vehicles - they simply have an OBD and an OBD-II section in the service manual.)

For example, the 94-95 Corvettes have one post-catalyst oxygen sensor (although they have two catalytic converters), and have a subset of the OBD-II codes implemented. For a 1994 Corvette the implemented OBD-II codes are P0116-P0118, P0131-P0135, P0151-P0155, P0158, P0160-P0161, P0171-P0175, P0420, P1114-P1115, P1133, P1153 and P1158.[5]

This hybrid system was present on the GM H-body cars in 94-95, W-body cars (Buick Regal, Chevrolet Lumina ('95 only), Chevrolet Monte Carlo ('95 only), Pontiac Grand Prix, Oldsmobile Cutlass Supreme) in 94-95, L-body (Chevrolet Beretta/Corsica) in 94-95, Y-body (Chevrolet Corvette) in 94-95, on the F-body (Chevrolet Camaro and Pontiac Firebird) in 95 and on the J-Body (Chevrolet Cavalier and Pontiac Sunfire) and N-Body (Buick Skylark, Oldsmobile Achieva, Pontiac Grand Am) in 95 and 96 and also on '94-'95 Saab vehicles with the normally aspirated 2.3.

For ALDL connections, pin 9 is the data stream, pins 4 and 5 are ground, and pin 16 is battery voltage.

An OBD 1.5 compatible scan tool is required to read codes generated by OBD 1.5.

Additional vehicle-specific diagnostic and control circuits are also available on this connector. For instance, on the Corvette there are interfaces for the Class 2 serial data stream from the PCM, the CCM diagnostic terminal, the radio data stream, the airbag system, the selective ride control system, the low tire pressure warning system, and the passive keyless entry system.[6]

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Your posted picture of MAX232 ALDL interface will work on my daewoo racer car model 1993 and it has 12 pin connector, attached,
:grin:

I already imagine that you trying to chip tunning that car, and trying to convince the car that can go over 200km/h.

imranahmed

### imranahmed

Points: 2

#### imranahmed

Is there any software for reading real time data from ECU by using ALDL MAx232 interface.

#### tpetar

Check this:

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http://www.techedge.com.au/vehicle/aldl160/aldl_sw.htm

http://winaldl.joby.se/

http://winaldl.joby.se/aldlcable.htm

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I think you have now enough material to wind up car to go over 200km/h.

#### Attachments

• winaldl_109f.rar
439.8 KB · Views: 12
imranahmed

### imranahmed

Points: 2

#### imranahmed

Please another question is that in my cars DLC connector have 12-pins pin-G have 12v volt when ignition
and engine both on and pin M and pin B have 5 volts and pin A is ground.where i will connect ALDL interface wire for transmission.

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#### tpetar

The signaling of ALDL is very similar to the RS-232 standard; differing only in the voltages used to denote logical one (usually 0VDC) and logical zero (either +5VDC or +12VDC).

All implementations of ALDL transmit serial data, and the voltages on the ALDL connector are similar to those of the RS-232 standard. Because of these similarities, schematics are available on the internet for devices that can be used to convert the ALDL voltages to that of the RS-232 standard, allowing the raw data to be read with any computer having a serial port. It should be noted that because of the largely undocumented nature of ALDL, determining the meaning of the raw data is not a straightforward process, free software exists that is compatible with many ALDL implementations to convert the raw data to human-readable format.

https://en.wikipedia.org/wiki/ALDL

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Its possible that someone change pins on connector. This is usually done for many reasons.

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First try circuit from post #6, that should work.

imranahmed

### imranahmed

Points: 2

#### imranahmed

Please i need Paramater IDs of suzuki sdl what i can do?

#### tpetar

Suzuki SDL connector pins :

A brief description of the Suzuki Serial Data Link (Suzuki SDL)
http://www.rhinopower.org/diag/sdl.html

Suzuki ECU Diagnostics Explained
http://www.rhinopower.org/diag/diag_main.html

OBD1 on an OBD2 ECU aka "Suzuki Mode"
http://www.rhinopower.org/diag/obd1vobd2.html

The ALDL connector has the SDL on pin M, Pins ? and ? provide 12V power and ground for a diagnostic scanner.
SDL uses pin 9 on the J1962 connector, ISO 9141-2 (OBD2) uses only the K-Line (pin 7).

Code:
Send To ECU

Header = $13 Message length =$04
Offset = $00 to unknown (will depend on ECU) Checksum = all bytes sum to zero ECU returns Header =$13
Messsage Length = $04 Data = ? Csum The offset is defined by a look up table in the ECU. This implies that there may be commonality between ECUs. The list below shows the addresses that I have determined so far for the EE88 EPROM. The first column is the OBD address, the second column is the actual memory address being read. I have made a prototype scanner to create the hardware interface. Parameter definitions will be filled in as work progresses. 00$0044 = Fault Codes
01 $0046 = Fault Codes 02$0045 = Stored fault codes??
03 $0047 = Stored fault codes?? 04$0187
05 $004D = RPMH, RPM High Byte (RPMH + RPML = RPM/4 06$004E = RPML, RPM Low Byte
07 $00D5 08$0093
09 $00DF = WTS 0A$00E0 = ATS
0B $9803 = ECU variant 0C$0070 = TPS Angle (referenced from idle switch
0D $005B = TPS Position 0E$005A = O2 Sensor Volts*2
0F $00AF = ISC Duty Cycle 10$00FE = Injector Pulse Width High byte
11 $00FF = Injector Pulse Width Low byte 12$0066 = Manifold Pressure
13 $0040 = Cylinder filling?? 14$00BA = Ignition Timing (degs)
15 $00D8 16$00F3 = Short term fuel trim
17 $00EB = Long term fuel trim 18$00E1
19 $00D9 1A$0058 = Battery Voltage * 0.0737288
1B $0188 1C$0186 = Flags? Bit2 = Fuel Pump?
1D $0095 1E$0079

SDLKWP

imranahmed

### imranahmed

Points: 2

#### imranahmed

Dear tpeter,

In my car daewoo the ECU is SER NO:1227303
but in your given ALDL software there is no model 1227307 but different no are given.
What can i do for my car real time data seeing please reply.

#### bianchi77

Please let know that can we set desired baud rate in 89c52 uC.
I want to set baud rate 8129.
Another question is that if system is design on 8129 baud rate so
can we communicate with 9600 or 4800 baud rates or its necessary
to communicate on 8129 baud rate?

Yes we can for 9600 and 4800 but I'm not sure for 8129, may be 8192 ?
have a look on this one :
https://www.keil.com/c51/baudrate.asp

Cheers

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Not easy mate for your 8129
May be you can not connect perfectly because the speed is not match