Innovate Serial Protocol #1

Date: 10/17/2003(.pdf version)

The LM-1 will output serial data always whether recording is on or off.

1. Serial Interface Settings

The LM-1 serial interface is set to

8 data bits
1 stop bit
no parity
19.2 kBaud.


2. Serial Protocol Format

The serial data consists of packets of 16 bytes (in normal operation every 81.92 msec).

The packets are organized as eight 16 bit numbers in big endian order.

Only the first Byte of a packet has the high bit set to denote a packet start.

The following table shows the bit/word order of a packet.
The descriptions of each WORD follows below.

The length of eight numbers may not be assumed. LM-1 versions without aux input may only send the first three words. LM1's with more than 5 aux inputs can send more words. During Warmup or error conditions the LM-1 may send only the first two words.

WORD Bit
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

0 1 R F3 F2 F1 F0 0 AF7 0 AF6 AF5 AF4 AF3 AF2 AF1 AF0
1 0 0 L12 L11 L10 L9 L8 L7 0 L6 L5 L4 L3 L2 L1 L0
2 0 0 mb2 mb1 mb0 bv9 bv8 bv7 0 bv6 bv5 bv4 bv4 bv2 bv1 bv0
3..7 0 0 0 0 0 Aux9 Aux8 Aux7 0 Aux6 Aux5 Aux4 Aux3 Aux2 Aux1 Aux0


The first word of a packet contains function/status information.
The second word contains Lambda or status detail information.
The third word contains the battery voltage as seen by the LM-1.
The remaining words contain digitized auxiliary input data digitized to 10 bits.

2.1 Function/Status Word (Word 0)


Bit 15 of always set

Bit 14 (R) is set if currently recording to Flash in LM-1

Bit 13..10 (Func3..0) are function/status bits how interpret the next word (Lambda Word).

Func3..0

0000 Lambda valid and Aux data valid, normal operation.
0001 Lambda value contains O2 level in 1/10%
0010 Free air Calib in progress, Lambda data not valid
0011 Need Free air Calibration Request, Lambda data not valid
0100 Warming up, Lambda value is temp in 1/10% of operating temp.
0101 Heater Calibration, Lambda value contains calibration countdown.
0110 Error code in Lambda value
0111 Lambda Value is Flash level in 1/10%
1xxx reserved

Bit 8 contains high bit (bit 7) of AFR multiplier (AF7)

Bit 7 always 0

Bit 6..0 contain remaining 7 bits of AFR multiplier (AF6..AF0).

AFR multiplier is stochiometric AFR value of current fuel setting in the LM-1 times 10. E.g. 147 for gasoline (14.7).
Air/Fuel Ratio = ((L12..L0) + 500)* (AF7..0) / 10000


2.2 Lambda Word (Word 1)

Lambda in 0.001 Lambda increments when F3..F0 is 0000, offset by 0.5 Lambda.

L = 0 -> 0.5 Lambda
L = 1022 -> 1.522 Lambda
L = 1023 Lambda = 1.523
L = 8191 Lambda = 8.691


2.3 Battery Voltage (Word 2)

Battery voltage digitized to 10 bit (bv9..bv0) and battery divider (mb2..mb0). Calculate battery voltage in Volt as
bv * 5 * mb / 1023.


2.4 Aux Input (Word 3..7)

Aux Inputs digitized to 10 bits. 0 = 0V, 1023 = 5V.

If RPM converter is used, Multiply WORD 3 value by 10 to get rpm.

Note: The serial protocol spec 1 is used for the LM-1 (six channel) only. The LC-1 and other Innovate products utilize serial protocol 2 (32 channels). Serial protocol 2 is available by request. Please contact technical support; please include information on your application and if the device in which the serial protocol will be used in will be for resale.
We also offer an SDK that is available for download on our Support page.

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