USB to RS232 adapter

chop · Joined: 23 Nov 2004 Posts: 1 Location: Malmoe, Sweden

Hi,
I have byed student development kit for 16F877A with mini-proto board, Windows IDE Compiler and ICD-S40. This ICD unit communicates to the PC and the debugging software over an RS232 connection and it workd fine with my desktop PC. I am intend to by the Acer Aspire 1362WLC Sempron-2800 which has not have a serial port but it has 4 x Hi-Speed USB - 4 pin USB typ A instead. I wondering if somebody know if this development kit works properly with USB-to-serial adapter on laptop instead?
thanks
regards
Chop

Mark · Joined: 07 Sep 2003 Posts: 2838 Location: Atlanta, GA

Not all USB -> Serial adapters are created equal. Meaning some may work while others may not.

rwyoung · Joined: 12 Nov 2003 Posts: 563 Location: Lawrence, KS USA

Mark is right. Not all USB to RS232 adapters are created equal. In my experience they tend to fall short in two area:

1) Control signals. Sometimes either the control signals aren't driven/sensed or the driver doesn't quite get it right.

2) Streaming data. Because USB is a packetized format, fast streaming data can cause some adapters problems. This has gotten much better over the years and I've seen very little trouble on newer USB1.1 and USB2.0 adapters but it still happens. What I've seen lately is time-outs on the perpherial as it waits for the PC to ACK something and the perpherial can't tolerate the 60ms (I think) maximum latency.

I suggest you call CCS and ask them if they will trade you (you paying the difference) for the USB version of the programmer/debugger.

Or ask them if they have experience with a particular brand of adapter that has worked for them.

Rob Young
rwyoung@ieee.org
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Rob Young
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