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Question - Building GM300 Prg Cable
Posted: Sun Apr 25, 2010 4:10 am
by dapaq2
Guys,
I am looking to build a programming cable for the Motorola GM300 and I have a question about the bias mentions on this page.
http://www.batlabs.com/images/maxpin.gif
It shows 1.7 BIAS, (Im assuming thats some sort of resistor?) What exactly is that and what do I need to get?
Thanks
Doug
Re: Question - Building GM300 Prg Cable
Posted: Sun Apr 25, 2010 4:27 am
by Bill_G
No. It's just a jumper from pin 4 to 11.
Re: Question - Building GM300 Prg Cable
Posted: Sun Apr 25, 2010 12:29 pm
by dapaq2
Oh ok, Thanks Bill. Kind of deceiving on the mention of "bias". I thought for sure it was some sort of resistor or capacitor required. Being that its just a jumper makes it much simpler. Again thanks for the reply and info.
Doug
Re: Question - Building GM300 Prg Cable
Posted: Sun Apr 25, 2010 12:37 pm
by jackhackett
You can see where the bias comes from in the RIB schematic, a simple voltage divider on the +5volts. This gets fed back into the RIB and biases the opamp in the RX portion of the serial interface.
Re: Question - Building GM300 Prg Cable
Posted: Sun Apr 25, 2010 2:46 pm
by dapaq2
It is pins 4 and 7 on the RJ45 connector, correct? I cannot quite tell by the diagram.
Doug
Re: Question - Building GM300 Prg Cable
Posted: Sun Apr 25, 2010 6:21 pm
by Al
Correct, 4 & 7.