ELM327LP datasheet(6/94 Pages) ELM

6 / 94 page

6 of 94

ELM327L DSA

Elm Electronics – Circuits for the Hobbyist

www.elmelectronics.com

ELM327L

If unused, pin 24 must be connected to a logic high

(VDD) level. The pin 24 CAN Rx input has Schmitt

trigger waveshaping.

RS232 Rx LED (pin 25), RS232 Tx LED (pin 26),

OBD Rx LED (pin 27) and OBD Tx LED (pin 28)

These four output pins are normally high, and are

driven to low levels when the ELM327 is transmitting

or receiving data. These outputs are suitable for

directly driving most LEDs through current limiting

resistors, or interfacing to other logic circuits. If

unused, these pins may be left open-circuited.

Note that pin 28 can also be used to turn off all of the

Programmable Parameters, if you can not do so by

using the normal interface - see page 70 for details.

Pin Descriptions (continued)

ELM327L Unused Pins

When people only want to implement a portion of what

the ELM327L is capable of, they often ask what to do

with the unused pins. The rule is that unused outputs

may be left open-circuited with nothing connected to

them, but unused inputs must always be terminated.

The ELM327L is a CMOS integrated circuit that can

not have any inputs left floating (or you might damage

the IC). Connect unused inputs as follows:

Level

Note that the inputs that are shown with an asterisk (*)

may be connected to either a High (VDD) or a Low

(VSS) level, but the level shown is preferred. Pin 6 is

not shown for the ELM327L as it must be connected to

a capacitor.

ELM327LP датащи(PDF) 6 Page - ELM Electronics