gordonl@microsoft.UUCP (Gordon LETWIN) (03/14/90)
I need a quick and easy PC interface to about 8 RS232 lines. Performance requirements are low so I was thinking of just wrapping a kuldge card with several UARTs. The last one I worked with was the 8250, 10 years ago or so. I find it very convenient, but I don't want to give up the real estate and power drain to put 8 of those on a card. If someone knows of a easy to use UART/USART, ideally CMOS and ideally multi-channel per package, I'd appreciate it if you could email me the part #; I'm sure that in the last 8 years there've been some good chips thanks gordon letwin
gordon@prls.UUCP (Gordon Vickers) (03/16/90)
In article <53558@microsoft.UUCP> gordonl@microsoft.UUCP (Gordon LETWIN) writes: >I need a quick and easy PC interface to about 8 RS232 lines. Performance >requirements are low so I was thinking of just wrapping a kuldge card >with several UARTs. The last one I worked with was the 8250, 10 years ago >or so. I find it very convenient, but I don't want to give up the real >estate and power drain to put 8 of those on a card. > >If someone knows of a easy to use UART/USART, ideally CMOS and ideally >multi-channel per package, I'd appreciate it if you could email me the >part #; I'm sure that in the last 8 years there've been some good chips > > thanks > gordon letwin Signetics, a division of Philips Components makes the SCC2698 : o CMOS o Octal UART o quadruple buffered receiver data register o Programmable data format : - 5 to 8 data bits plus parity - Odd, even, no parity, or force parity - 1, 1.5 or 2 stop bits o Baud rate for receiver and transmitter selectable from : - 18 fixed rates: 50 to 38.4K - four user-defined rates derived from the programmable counter/timer associated with each of the four blocks - External 1X or 16X clock o Parity, framing, and overrun error dectection o False start bit detection o Line break detection and generation o Programmable channel mode : - Normal (full duplex), automatic echo, local loopback, remote loopback o Four multi-function programmable 16-bit counter/timers o Four interrupt outputs with eight maskable interrupting conditions for each output o On-chip crystal oscillator o TTL compatible o Single +5V power supplly with low power mode Gordon Vickers 408/991-5370, at Signetics (Sunnyvale, California, USA ) {mips|pyramid|philabs}!prls!facv01!gordon ** All disclaimers apply ** Earth is a complex array of symbiotic relationships: Every extinction, whether animal, mineral, vegetable, or cultural hastens our own demise.
henry@utzoo.uucp (Henry Spencer) (03/16/90)
In article <34002@prls.UUCP> gordon@prls.UUCP (Gordon Vickers) writes: > Signetics, a division of Philips Components makes the SCC2698 ... Not to be cynical or anything :-), but given how nice it sounds otherwise, and knowing Murphy like I do, I assume it's in one of those zillion-pin packages that are hell for hobbyists to work with, and it's set up to interface to Intel processors and nothing else? Oh yes, and it costs $500 in quantity 100 and is on allocation? (I'd be happy to hear that I'm wrong...) -- MSDOS, abbrev: Maybe SomeDay | Henry Spencer at U of Toronto Zoology an Operating System. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
george@wombat.UUCP (George Scolaro) (03/19/90)
In article <1990Mar16.055156.19874@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes: >In article <34002@prls.UUCP> gordon@prls.UUCP (Gordon Vickers) writes: >> Signetics, a division of Philips Components makes the SCC2698 ... > >Not to be cynical or anything :-), but given how nice it sounds otherwise, >and knowing Murphy like I do, I assume it's in one of those zillion-pin >(I'd be happy to hear that I'm wrong...) The SCC2698 is available in DIP (big) or PLCC. I have used the PLCC version, which is 84 pins and has more i/o than the DIP ('cos its got more pins) and it works very well. In small quantities it is around $25-30. The only problem with the part (not a bug as such) is that it lacks sufficient handshake signals. It would be really nice if it had tx/rx/cts/rts and dcd/dtr. Unfortunately Signetics gave the chip a bucket of general purpose inputs, but not enough general purpose outputs, so you need an external latch to take care of the dtr. The nice part is that it does do hardware flow control with rts/cts. It's program model is nearly 100% the same as 4 separate SCN2681 Duarts. The original requestor of info was worried about prototyping with PLCC. What I have done in the past is to get a normal solder tail PLCC socket and then push on a PGA wirewrap socket (lots of push) and then you have a PLCC wirewrap socket. regards, -- George Scolaro george@wombat.bungi.com [37 20 51 N / 122 03 07 W]
henry@utzoo.uucp (Henry Spencer) (03/19/90)
In article <445@wombat.UUCP> george@wombat.UUCP (George Scolaro) writes: >...The only >problem with the part (not a bug as such) is that it lacks sufficient >handshake signals... Signetics gave the chip a bucket of general purpose >inputs, but not enough general purpose outputs, so you need an external >latch to take care of the dtr... This is actually the right decision if you are short of pins. Inputs generally want things like edge detectors, to provide an interrupt when something changes, and those are hard to do yourself. Outputs just want latches, which are off-the-shelf parts. -- MSDOS, abbrev: Maybe SomeDay | Henry Spencer at U of Toronto Zoology an Operating System. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
george@wombat.UUCP (George Scolaro) (03/20/90)
In article <1990Mar19.014241.5473@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes: >In article <445@wombat.UUCP> george@wombat.UUCP (George Scolaro) writes: >>...The only >>problem with the part (not a bug as such) is that it lacks sufficient >>handshake signals... Signetics gave the chip a bucket of general purpose >>inputs, but not enough general purpose outputs, so you need an external >>latch to take care of the dtr... > >This is actually the right decision if you are short of pins. Inputs But they weren't short of pins. They have 16 pins for external clocks, 8 for the receivers and 8 for the transmitters (note these pins can also be outputs, the part is very programmable). Now, the normal user of this part will want full modem control and the same baud rate on each receiver - transmitter, so freeing up 8 outputs for dtr. In output mode the 16 pins become TxRDY and RxRDY/FFULL, which don't seem to useful since they can be read from within the part via registers. Their only use is to (optionally) wire-or them to generate RxRDY or TxRDY interrupts (in addition to the 4 separate interrupts that come from each pair of channels - like the 2681 DUART). It just seems to me that a slightly different selection (or superset) of options would have made the part a single chip solution rather than needing a separate latch and hence decode circuit plus pcb routing etc... Note: The part has programmable baud rate control for each of the channels internally. The reason for the external baud rate control is for some of the higher rates (such as 115kbaud). Also, Signetics have rev-ed the part from the original version (this is the 2698B), and in doing so changed the assignments of some of the input/output functions, but so close to perfect.... regards, -- George Scolaro george@wombat.bungi.com [37 20 51 N / 122 03 07 W]