Avoiding Reset

dnaddor

We use the serial interface of the propeller chip as part of our product.

If I open the COM port normally, the chip will reset when it is opened, but not when it is closed.

If I play with the DTR settings in the DCB, I can get the chip not to reset when I open the port. But then it resets when I close the port!

Is there a way to open and close the COM port without causing a reset?

Thanks!

Paul Baker

Install a jumper + block on the RESn line from the programming interface, have the block in place when you need to program the Propeller, remove it during normal operation.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

dnaddor

Unfortunately, the Propeller chip is on a board that is installed inside of our customer's PC. The main reason we switched to the Propeller chip from the SX48 is that we needed our application software to be able to upgrade the firmware code if needed without customer intervention. (We used to just send them a new board and they would send us back the old one. Customers don't like opening up PCs.)

We may just put pullups on the couple of the hardware lines that go to the wrong state when the Propeller chip resets. I was hoping for a software-only solution without having to spin another board, but this may not be possible.

Phil Pilgrim (PhiPi)

dnaddor,

This could be done in software, using two programs on the PC:

1) a small "daemon" or server that runs all the time and controls the serial port, keeping it open constantly, and

2) a client program that runs on demand and communicates with the daemon via a local TCP or UDP port.

Essentially, you'd be creating your own serial driver wrapper that keeps the port open and uses network protocols for external communication.

-Phil

dnaddor

Good idea. Thanks!

Steve Hicks (N5AC)

I was having a different problem when avoiding reset, but I thought I would post it here in case others encounter this problem.· My propeller board is about 3" from an antenna which is transmitting with 7W of VHF and the voltage produced on the reset line was resetting the processor -- whenever the radio would transmit, the propeller would reset.· My board is built around the DIP part and the line for the reset was long, so I have re-layed out the board for SMT, greatly reduced the "antennas" on the board and done some bypassing of the reset circuit (see attached schematic).· The boards are in manufacturing in China, but I'll post an update when I find out if all of this has solved the problem.

Steve

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Steve, N5AC