Thread: Have electronic device get power from OBD2 only when car is running?

Originally Posted by paimon.soror

Hey all, quick question. I have a device that I created that reads information from the OBD2 port. I was wondering if there was a way for me to be able to make the device only be on when the car is running? Is there a way to do this without tapping into any switchable power source? For example, does the car battery run at a certain voltage when the car is on vs off so that i can use a relay of sort? thanks.

Yes, it is possible. You can design a device to do what you described, or use the built-in PowerSave functionality of STN1110.

http://www.scantool.net/downloads/79...-powersave.pdf

STN1110 can sleep/wake up on voltage level, and it can wake up on voltage change (which is the most sensitive/reliable way). It also lets you set custom timeouts (e.g., voltage<12.5V for 10 minutes).

You can request a free sample of STN1110 from obdsol.com.

Vitaliy

Oh very interesting, i have to admit that I am currently using the MCP2551 and MCP2515 chips to do my OBD work. Off the top of your head you dont know if those chips do something similar to the STN device do you?

Phew!

The thread title reminded me of a job advert seeking someone to design something that would "take power" from GSM mobile phone transmissions. (I presume for a mobile phone etc.)

I doubt they got any takers, though I was tempted to inquire.

Originally Posted by paimon.soror

Oh very interesting, i have to admit that I am currently using the MCP2551 and MCP2515 chips to do my OBD work. Off the top of your head you dont know if those chips do something similar to the STN device do you?

No, they do not -- PowerSave is functionality we had to build into the firmware. See the datasheet for a description of the IC:

http://www.scantool.net/scantool/dow...stn1110-ds.pdf

Read the Family Reference and Programming Manual for more information:

http://www.scantool.net/scantool/dow...n1100-frpm.pdf

Vitaliy