View Full Version : alternative serial port connection

04-28-2008, 11:02 AM
I will be using a MAX3235 in place of the discrete circuit show in Figure 2.3.2 on page 5 of the Prop Datasheet.

I see that the DTR line (pin 4 of the DB9) to the prop's RESn line has a pull-up resistor in it.

Will the pull-up resistor and the 0.1uF cap still be required with the MAX3235 chip?

Mike Green
04-28-2008, 12:44 PM
Consider the circuit for the Propeller Demo Board which uses an FTDI USB to serial interface chip that provides a similar serial interface as many RS232 interfaces like the MAX3235. You will need 1K protective resistors in the RX lines from the MAX3235 since it's a 5V chip and the RX line from the MAX3235 goes between 5V and 0V.