Connecting Micro Motor Control To BS2

kenwtn

I have recently purchased the Micro Dual Serial Motor Control from Parallax. My question is after reading the PDF I downloaded from Parallax it shows a circuit to protect your PC if connecting directly to the serial port of a PC. Do I need to use the same protection when connecting to a BS2? If that circuit is not needed are there any other things I should consider when connecting to a BS2?

Mike Green

The voltages at most serial ports can damage a logic circuit like the Motor Controller without some protective resistors as shown.

The Stamp already has logic level outputs and inputs. There are diagrams later in the Motor Controller documentation that show how to connect it to a microcontroller like a Stamp. There's also a sample BS2 program. Follow the directions in the documentation.

kenwtn

OOPS new this forum. Do I just need to put a 470 resistor in line with the RESET and Serial Lines?

Mike Green

It's not really necessary because the Motor Controller pins are input-only. There's no possibility of them becoming outputs and particularly outputs of the opposite logic state as the Stamp pins. The series resistors are intended to prevent damage if: 1) You have two chips running at different logic levels (3.3V and 5V typically) or 2) You have two pins that could both become outputs (through programming error) with one pin at logic zero (Vss or ground) and the other at logic one (Vdd or +5V or +3.3V). This would create a short circuit.

kenwtn

Ok Thanks I believe I got it now