>>I am thinking about a small controller but most only have two UARTS and >doing four in software at 38400 seems quite a challenge to me. So maybes>small FPGA/CPLD solution would be in order. But most of all, it needs tobe>simple, cheap and small footprint. >It is possible to implement up to 4 UARTs in some of the Cypress PSoCs. You could also implement an SPI interface. If the serial ports do not have to be active concurrently, it would be possible to use fewer UARTs and multiplex them to different pins on the IC. -Aubrey
Cheap, small quad UART needed
Started by ●March 15, 2007
Reply by ●March 15, 20072007-03-15
Reply by ●March 16, 20072007-03-16
"Meindert Sprang" <ms@NOJUNKcustomORSPAMware.nl> skrev i meddelandet news:45f92098$0$22652$e4fe514c@dreader14.news.xs4all.nl...> Hi Guru's > > I need a quad UART chip with only RXD and TXD per channel, no handshake > required, preferable communicating with my CPU through an SPI port. > Baudrates in the range of 4800 to 38400 baud. Oh, and it needs to be > cheap. > > I am thinking about a small controller but most only have two UARTS and > doing four in software at 38400 seems quite a challenge to me. So maybe s > small FPGA/CPLD solution would be in order. But most of all, it needs to > be > simple, cheap and small footprint. > > All suggestions are welcome. > > Meindert > >AT91SAM7S321 in QFN-64 (AT91SAM7S161 when available)? 3 x H/W UART and you can probably use the SSC as H/W support for 4th UART. All UARTs including SSC has DMA support. -- Best Regards, Ulf Samuelsson This is intended to be my personal opinion which may, or may not be shared by my employer Atmel Nordic AB
Reply by ●March 16, 20072007-03-16
On Fri, 16 Mar 2007 06:20:08 +0100, "Ulf Samuelsson" <ulf@a-t-m-e-l.com> wrote:><snip> >AT91SAM7S321 in QFN-64 (AT91SAM7S161 when available)?I seem to recall this from Meindert, earlier: "My ideal UART looks like 20 pins max, maybe a 32 pin TQFP for $5 max." ^^^^^^^^^^^ ^^^^^ Jon
Reply by ●March 16, 20072007-03-16
"Jonathan Kirwan" <jkirwan@easystreet.com> wrote in message news:4rekv29qok8knpjuue6fl55rcjr9pgg4c1@4ax.com...> On Fri, 16 Mar 2007 06:20:08 +0100, "Ulf Samuelsson" > <ulf@a-t-m-e-l.com> wrote: > > ><snip> > >AT91SAM7S321 in QFN-64 (AT91SAM7S161 when available)? > > I seem to recall this from Meindert, earlier: "My ideal UART looks > like 20 pins max, maybe a 32 pin TQFP for $5 max." > ^^^^^^^^^^^ ^^^^^But ideal and real can be worlds apart, of course :-) Meindert
Reply by ●March 16, 20072007-03-16
"Meindert Sprang" <ms@NOJUNKcustomORSPAMware.nl> writes:> "Jonathan Kirwan" <jkirwan@easystreet.com> wrote > > "Ulf Samuelsson" <ulf@a-t-m-e-l.com> wrote: > > > > ><snip> > > >AT91SAM7S321 in QFN-64 (AT91SAM7S161 when available)? > > > > I seem to recall this from Meindert, earlier: "My ideal UART looks > > like 20 pins max, maybe a 32 pin TQFP for $5 max." > > ^^^^^^^^^^^ ^^^^^ > > But ideal and real can be worlds apart, of course :-)If you want an 8-bit parallel interface on one side and a Rx and Tx line per port on the other, you're at 16 already. Some address lines for selecting the internal registers, CS, power, and ground and you're past 20 pins. You might be able to make it in 32 pins and have some hardware handshake pins.
Reply by ●March 16, 20072007-03-16
"Everett M. Greene" <mojaveg@mojaveg.lsan.mdsg-pacwest.com> wrote in message news:20070316.7A4ED78.93A3@mojaveg.lsan.mdsg-pacwest.com...> "Meindert Sprang" <ms@NOJUNKcustomORSPAMware.nl> writes: > > "Jonathan Kirwan" <jkirwan@easystreet.com> wrote > > > "Ulf Samuelsson" <ulf@a-t-m-e-l.com> wrote: > > > > > > ><snip> > > > >AT91SAM7S321 in QFN-64 (AT91SAM7S161 when available)? > > > > > > I seem to recall this from Meindert, earlier: "My ideal UART looks > > > like 20 pins max, maybe a 32 pin TQFP for $5 max." > > > ^^^^^^^^^^^ ^^^^^ > > > > But ideal and real can be worlds apart, of course :-) > > If you want an 8-bit parallel interface on one side andNo, I wanted an SPI interface.> a Rx and Tx line per port on the other, you're at 16 > already. Some address lines for selecting the internal > registers, CS, power, and ground and you're past 20 pins. > You might be able to make it in 32 pins and have some > hardware handshake pins.
Reply by ●March 16, 20072007-03-16
kkkisok@operamail.com wrote:> On 15-Mar-2007, "Meindert Sprang" <ms@NOJUNKcustomORSPAMware.nl> wrote: > >> Hi Guru's >> >> I need a quad UART chip with only RXD and TXD per channel, no handshake >> required, preferable communicating with my CPU through an SPI port. >> Baudrates in the range of 4800 to 38400 baud. Oh, and it needs to be >> cheap. >> >> I am thinking about a small controller but most only have two UARTS and >> doing four in software at 38400 seems quite a challenge to me. So maybe s >> small FPGA/CPLD solution would be in order. But most of all, it needs to >> be >> simple, cheap and small footprint. >> >> All suggestions are welcome. >> >> Meindert > > http://www.nxp.com/products/interface_control/i2c_bridge/index.htmlRealy nice product indeed. This goes for $2.50 for 1 channel and $4 for 2 channel device in single quantity at Digikey. Seems this is exactly what OP is searching for. Thanks for the link.
Reply by ●March 16, 20072007-03-16
On Mar 15, 6:29 am, "Meindert Sprang" <m...@NOJUNKcustomORSPAMware.nl> wrote:> Hi Guru's > > I need a quad UART chip with only RXD and TXD per channel, no handshake > required, preferable communicating with my CPU through an SPI port. > Baudrates in the range of 4800 to 38400 baud. Oh, and it needs to be cheap. > > I am thinking about a small controller but most only have two UARTS and > doing four in software at 38400 seems quite a challenge to me. So maybe s > small FPGA/CPLD solution would be in order. But most of all, it needs to be > simple, cheap and small footprint. > > All suggestions are welcome.I don't see where you got much discussion on CPLDs. There are any number of CPLDs in small packages. However, they don't typically have as small pin counts as you would like, 20/32 pins. They tend to start around 48 pins for CPLDs, but a 48 pin TQFP is a pretty small device. Most CPLDs will be register limited however. To implement 4 UARTs and an SPI interface, you will need to define a protocol for the SPI interface and it will require most likely a command word to be written for each byte transferred in either direction. I estimate about 24 FFs for the SPI including the state machine (off the top of my head). You will need some 20 FFs per receiver and another 24 per transmitter if you want it double buffered. The baud rate generator can be in the range of 8 to 16 FF. So this totals some 200+ which puts you in a 256 MC CPLD. These tend to be a bit pricey and are typically not available in a small package. So your MCU approach is likely to be the best. There are parts that can do this job easily, but you will need to go with a BGA to even get close to a small package. I have seen FPGA vendors discuss how there is little demand for higher density devices in smaller pin count packages. I often wonder if that is really the case or if it is really just a matter of them wanting to pick the low hanging fruit rather than to compete on lower margin devices. They don't have to sell very many $1000 FPGAs to bring in more profit than the $4 parts. But I know I have had applications for small FPGAs in low pin count packages.
Reply by ●March 17, 20072007-03-17
Meindert Sprang wrote:> Hi Guru's > > I need a quad UART chip with only RXD and TXD per channel, no handshake > required, preferable communicating with my CPU through an SPI port. > Baudrates in the range of 4800 to 38400 baud. Oh, and it needs to be cheap. > > I am thinking about a small controller but most only have two UARTS and > doing four in software at 38400 seems quite a challenge to me. So maybe s > small FPGA/CPLD solution would be in order. But most of all, it needs to be > simple, cheap and small footprint. > > All suggestions are welcome.Have you looked at Philips / Exar ? Don't forget to include 2 x Dualchannel uC as they may still be cheaper than a Quad solution. If this has to be 'no shortcuts' with full duplex, full buffering, and handshake, then it's going to push a single uC, and for CPLDs you'll also find it hard to source one that is going to compete with 2 cheap uC, in $ and PCB area. Something like the AT89LP216 from Atmel, at ~90c/10K, will do 1 Chan in HW, and probably 1 more in SW, so that's ~ $2 - the new SiLabs C8051T600 has i2c, no SPI, but thats getting under 50c for a single channel. most likely CPLD,resource wise, would be the Lattice MachXO,but they start at 100 pins.. -jg
Reply by ●March 17, 20072007-03-17
Technical support when I am not available: AT89 C51 Applications Group: mailto:micro.hotline@nto.atmel.com AT90 AVR Applications Group: mailto:avr@atmel.com AT91 ARM Applications Group: mailto:at91support@atmel.com FPSLIC Application Group: mailto:fpslic@atmel.com Best AVR link: www.avrfreaks.net "Jonathan Kirwan" <jkirwan@easystreet.com> skrev i meddelandet news:4rekv29qok8knpjuue6fl55rcjr9pgg4c1@4ax.com...> On Fri, 16 Mar 2007 06:20:08 +0100, "Ulf Samuelsson" > <ulf@a-t-m-e-l.com> wrote: > >><snip> >>AT91SAM7S321 in QFN-64 (AT91SAM7S161 when available)? > > I seem to recall this from Meindert, earlier: "My ideal UART looks > like 20 pins max, maybe a 32 pin TQFP for $5 max." > ^^^^^^^^^^^ ^^^^^ > > JonBoth are 9 x 9 mm, whats the big deal ?? It'll do the job, and it is in the price range. -- Best Regards Ulf Samuelsson
