| Author | Message | ||
     Greg_e |
This is probably a pointless post that will go unanswered, but does anyone know if there is a voltage on the serial port TX line? This is the line that receives the signal from the serial device and I know it is setup to deal with a 5 volt signal, but I'm wondering if it has a 5 volt pullup on it, or if it is a no voltage input line? It matters for a device I'm making which is only 3.3 volt logic and will fry if I send 5 volts into it. | ||
| Greg_e |
In case anyone else is wondering and decides to do a search, both RXD and TXD are pulled up to +5 volts at the ECM. You may need a level shifter if your device will not work with 5 volt signals. | ||
| Brakes2late |
I have used a 3.3v USB to TTL converter cable to communicate with an ECM using ECMSpy w/o any issue. | ||
| Greg_e |
You're lucky many of those device will permanently fail with the extra voltage. Also the TX side will not work if you hit it with much less voltage. I had a device that was sending a little over 2.5 volts and the ECM did not acknowledge the signal. |
