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Gary,
That's a nice summary. In hind sight, I don't think I needed to bother with full Modem controls on my board. I seriously doubt anyone will ever use them. I did it only because they were there on the UART chip. I think #2 is plenty, with the addition of asserting DTR permanently by connecting it to +12V. Cheers for the summary, Josh > Date: Sun, 16 Nov 2014 05:35:56 -0800 > From: gregor...@gmail.com > To: n8vem...@googlegroups.com > Subject: Re: [N8VEM-S100:5605] S100 Serial IO Design Question > > RS-232 (serial communications) can be grouped into 3 typical implementation types. > > 1.) 3-wire usage. RxD, TxD, and GND (dara lines). Basic connection, easiest for USB conversion. > > 2.) 5-wire usage. RxD, TxD, GND (data), plus RTS, CTS (control lines) for Hardware Flow Control. > Schematic of typical FTDI FT232R cable (USB to TTL conversion chip) for 5-wire (UART/TTL) to USB. > https://www.sparkfun.com/datasheets/DevTools/FTDI%20Cable%205V.pdf > > Beauty of the FT232R series is that serial lines (UART/TTIL) can be inverted via software configuration (EEPROM), > without additional hardware. > > 3.) 9-wire (AT-style support). 1984 implemenation of RS-232 with DE-9F connector. > Largely fallen out of favor as Dial-Up (POTS) modems (that used RI, ring indicator line) > disappeared at beginning of 21st century (or last 10 years). > > 4.) Custom Variations. Software Applications and custom hardware devices have been known to use the 6 serial control lines (RTS, CTS, DTR, DSR, DCD, RI) > for other non-standard purposes (signaling or control). > SOME implementations of the PIC, ATmega, Arduino boards use the DTR/DSR lines for slave processor signaling (ready, reset, etc.). > > G. Beat > chicago > > -- > You received this message because you are subscribed to the Google Groups "N8VEM-S100" group. > To unsubscribe from this group and stop receiving emails from it, send an email to n8vem-s100+...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. |