View Full Version : Protoboard USB question

03-26-2012, 07:49 PM
Hi all,

I've a couple questions concerning the Prop Protoboard USB. I'm assuming that the USB port replaces the old Prop Plug version for programming. Once programmed, could the USB port be used as a serial port interface to a PC via a virtual serial port? Would I need any sort of delay after bootup to communicate back to the PC? Will the DTR off the FTDI chip reset the Prop on power up of the USB port? I realize these questions might be obvious, but I want to make sure before I go to order the USB version, or if there will be any pitfalls I might need to know about.

The project will be to simply to have the PC polling the Protoboard for data, so everything will be initiated from the PC.


Mike Green
03-26-2012, 07:59 PM
The Prop Protoboard USB is functionally identical to a Prop Protoboard Serial + PropPlug. The DTR signal will reset the Prop when the USB port is opened. You don't need any programming delay before transmitting to the PC or receiving from the PC. Usually the Prop program uses the state of the receive line to tell when the PC is ready to send. If the receive line is high, the PC probably has finished initializing the serial port since the resting state of a serial line is normally high. When the serial line is low for an extended period, that's considered a break state or the line is not working (yet).

I'd have the PC open the serial port and periodically send some kind of unique identification sequence like "!!Prop?". The Prop code would initialize its serial I/O and look for this, then send something like "!!Yes?". When the PC gets this response, both serial directions are working and the two programs are in sync.