Hi, Hoping I can benefit from the collective wisdom of the folks on this newsgroup. What I am looking for is a simple UART / serial / RS-232 interface (I know those terms aren't interchangeable), with minimum cost being the goal. The product sales will be in the 50k unit range annually, and the selling price won't be very high at all a few 10s of dollars, if not cheaper. The difference between a $1.50 chip and a $0.50 solution becomes pretty significant. Basically I need to add 2 more serial interfaces and the microcontroller only has 1 on-chip (i.e. need to go from 1 serial interface to 3). The 2 new serial interfaces (added to a legacy product) will run 19200 baud, N-8-1. I don't fancy hardware flow control, BREAK detection, etc... just RX, TX and GND on the serial side. On the side interfacing to the microcontroller, almost anything is fine (8-bit parallel, SPI, I2C, whatever......) -- preferably with an interrupt line running to the micro saying "I have a byte". No FIFO/buffering is needed, the micro can respond quickly to an interrupt, but there isn't enough remaining CPU horsepower to implement 2 software UARTs. Issues like framing errors, parity errors, etc... can just discard the data and not bother the micro. Ultimately, I'd like a piece of silicon that says "Got another byte for you, come get it". On the transmit side, I just want to "write" a byte to the solution, whatever the interface, and know that the byte is going to be shifted out at 19200. Higher level protocols will handle dropped bytes in either direction. From a silicon standpoint, I don't care if it's one chip with the 2 UARTs, or 2 pieces of duplicate technology (actually 2 single-UART pieces would be ideal in the sense that another design might only need 1 additional "UART) So, is the best solution a tiny micro with someone's firmware? A PLD? Something else? I'm looking for something ready to go, i.e. I could implement this on any number of micros, as could most people here, but I need cheap and ready-to-go. I hope I've provided enough information, I've tried to anticipate questions out of respect for those kind enough to help out. All the best & thanks again.
Need low-cost
Started by ●February 13, 2006
Reply by ●February 13, 20062006-02-13
In article <4NydnUPsMpJ9rWzeRVn-iQ@giganews.com>, v2epl3e02 @sneakemail.com says...> Hi, > > Hoping I can benefit from the collective wisdom of the folks on this > newsgroup. > > What I am looking for is a simple UART / serial / RS-232 interface (I know > those terms aren't interchangeable), with minimum cost being the goal. > > The product sales will be in the 50k unit range annually, and the selling > price won't be very high at all a few 10s of dollars, if not cheaper. The > difference between a $1.50 chip and a $0.50 solution becomes pretty > significant. > > Basically I need to add 2 more serial interfaces and the microcontroller > only has 1 on-chip (i.e. need to go from 1 serial interface to 3). The 2 > new serial interfaces (added to a legacy product) will run 19200 baud, > N-8-1. > > I don't fancy hardware flow control, BREAK detection, etc... just RX, TX > and GND on the serial side. On the side interfacing to the > microcontroller, almost anything is fine (8-bit parallel, SPI, I2C, > whatever......) -- preferably with an interrupt line running to the micro > saying "I have a byte". > > No FIFO/buffering is needed, the micro can respond quickly to an > interrupt, but there isn't enough remaining CPU horsepower to implement 2 > software UARTs. Issues like framing errors, parity errors, etc... can > just discard the data and not bother the micro. > > Ultimately, I'd like a piece of silicon that says "Got another byte for > you, come get it". On the transmit side, I just want to "write" a byte to > the solution, whatever the interface, and know that the byte is going to be > shifted out at 19200. Higher level protocols will handle dropped bytes in > either direction. > > From a silicon standpoint, I don't care if it's one chip with the 2 UARTs, > or 2 pieces of duplicate technology (actually 2 single-UART pieces would be > ideal in the sense that another design might only need 1 additional "UART) > > So, is the best solution a tiny micro with someone's firmware? A PLD? > Something else? > > I'm looking for something ready to go, i.e. I could implement this on any > number of micros, as could most people here, but I need cheap and > ready-to-go. > > I hope I've provided enough information, I've tried to anticipate > questions out of respect for those kind enough to help out. > > All the best & thanks again.2 x Max3100 SPI UARTS. CPLD or programmable logic---but watch out for the engineering cost at 50,000 units (Unless your're proud of working cheap). Small At91SAM7 using two UARTs for external comms and one to communicate with main MPU via spi. If you already have an external data bus for RAM or FLASH, find another chip select and use a real UART (ST16C654 is the one I use). A bit more information about the main processor and system would be helpful. When it gets down to programming an MPU or CPLD, receiving is MUCH more difficult thanb transmitting. Mark Borgerson
Reply by ●February 14, 20062006-02-14
Mark Borgerson wrote:> In article <4NydnUPsMpJ9rWzeRVn-iQ@giganews.com>, v2epl3e02 > @sneakemail.com says... > >>Hi, >> >>Hoping I can benefit from the collective wisdom of the folks on this >>newsgroup. >> >>What I am looking for is a simple UART / serial / RS-232 interface (I know >>those terms aren't interchangeable), with minimum cost being the goal. >> >>The product sales will be in the 50k unit range annually, and the selling >>price won't be very high at all a few 10s of dollars, if not cheaper. The >>difference between a $1.50 chip and a $0.50 solution becomes pretty >>significant. >> >>Basically I need to add 2 more serial interfaces and the microcontroller >>only has 1 on-chip (i.e. need to go from 1 serial interface to 3). The 2 >>new serial interfaces (added to a legacy product) will run 19200 baud, >>N-8-1. >> >>I don't fancy hardware flow control, BREAK detection, etc... just RX, TX >>and GND on the serial side. On the side interfacing to the >>microcontroller, almost anything is fine (8-bit parallel, SPI, I2C, >>whatever......) -- preferably with an interrupt line running to the micro >>saying "I have a byte". >> >>No FIFO/buffering is needed, the micro can respond quickly to an >>interrupt, but there isn't enough remaining CPU horsepower to implement 2 >>software UARTs. Issues like framing errors, parity errors, etc... can >>just discard the data and not bother the micro. >> >>Ultimately, I'd like a piece of silicon that says "Got another byte for >>you, come get it". On the transmit side, I just want to "write" a byte to >>the solution, whatever the interface, and know that the byte is going to be >>shifted out at 19200. Higher level protocols will handle dropped bytes in >>either direction. >> >>From a silicon standpoint, I don't care if it's one chip with the 2 UARTs, >>or 2 pieces of duplicate technology (actually 2 single-UART pieces would be >>ideal in the sense that another design might only need 1 additional "UART) >> >>So, is the best solution a tiny micro with someone's firmware? A PLD? >>Something else? >> >>I'm looking for something ready to go, i.e. I could implement this on any >>number of micros, as could most people here, but I need cheap and >>ready-to-go. >> >>I hope I've provided enough information, I've tried to anticipate >>questions out of respect for those kind enough to help out. >> >>All the best & thanks again. > > > > 2 x Max3100 SPI UARTS.Digikey has these for 3.25/2500 pcs. Maxim-ic.com has them for 2.79 for 1K up. But you would need two. A single chip cpu bit banged can do 19200, even on two or three ports. Finding the right cpu would be a challange.> > CPLD or programmable logic---but watch out for the engineering cost > at 50,000 units (Unless your're proud of working cheap).The engineering cost is the same for one or 50K. Once the software/vhdl is written, the next 49,999 is free.> > > Small At91SAM7 using two UARTs for external comms and one to > communicate with main MPU via spi. > > > If you already have an external data bus for RAM or FLASH, find > another chip select and use a real UART (ST16C654 is the one I use).TI's version is 2.80/1k. http://focus.ti.com/docs/prod/folders/print/tl16c752b.html> > > A bit more information about the main processor and system > would be helpful.Yes, that would be good.> > When it gets down to programming an MPU or CPLD, receiving > is MUCH more difficult thanb transmitting.Depends on the cpu and how effecient is runs code. The Op said he could write this himself, so could many here ( even me :-). But he was hoping to get it right away. Good Luck. donald PS: as they say, timing is everything.
Reply by ●February 14, 20062006-02-14
Mark Borgerson wrote:> In article <4NydnUPsMpJ9rWzeRVn-iQ@giganews.com>, v2epl3e02 > @sneakemail.com says... > >>Hi, >> >>Hoping I can benefit from the collective wisdom of the folks on this >>newsgroup. >> >>What I am looking for is a simple UART / serial / RS-232 interface (I know >>those terms aren't interchangeable), with minimum cost being the goal. >> >>The product sales will be in the 50k unit range annually, and the selling >>price won't be very high at all a few 10s of dollars, if not cheaper. The >>difference between a $1.50 chip and a $0.50 solution becomes pretty >>significant. >> >>Basically I need to add 2 more serial interfaces and the microcontroller >>only has 1 on-chip (i.e. need to go from 1 serial interface to 3). The 2 >>new serial interfaces (added to a legacy product) will run 19200 baud, >>N-8-1. >> >>I don't fancy hardware flow control, BREAK detection, etc... just RX, TX >>and GND on the serial side. On the side interfacing to the >>microcontroller, almost anything is fine (8-bit parallel, SPI, I2C, >>whatever......) -- preferably with an interrupt line running to the micro >>saying "I have a byte". >> >>No FIFO/buffering is needed, the micro can respond quickly to an >>interrupt, but there isn't enough remaining CPU horsepower to implement 2 >>software UARTs. Issues like framing errors, parity errors, etc... can >>just discard the data and not bother the micro. >> >>Ultimately, I'd like a piece of silicon that says "Got another byte for >>you, come get it". On the transmit side, I just want to "write" a byte to >>the solution, whatever the interface, and know that the byte is going to be >>shifted out at 19200. Higher level protocols will handle dropped bytes in >>either direction. >> >>From a silicon standpoint, I don't care if it's one chip with the 2 UARTs, >>or 2 pieces of duplicate technology (actually 2 single-UART pieces would be >>ideal in the sense that another design might only need 1 additional "UART) >> >>So, is the best solution a tiny micro with someone's firmware? A PLD? >>Something else? >> >>I'm looking for something ready to go, i.e. I could implement this on any >>number of micros, as could most people here, but I need cheap and >>ready-to-go. >> >>I hope I've provided enough information, I've tried to anticipate >>questions out of respect for those kind enough to help out. >> >>All the best & thanks again.What chip are you using now ? CPLD _could_ do this, but at a package size, and price that is probably too high, is you went to the trouble to clone a full Duplex UART. It might get small enough to go sub $1 in CPLD, if you mixed HW/SW, but that puts some load on your present uC (but much less that full uarts), and thus it depends on how loaded that is ?. At 19K2, you can look at SW assisted UARTs, in separate uC. Package size is better on small uC, with new 14/16 pin ones from Atmel looking good. Ideal candidates would be AT89LP2052, or AT89LP213/4/6 These are comfortably sub $1, and have 1 UART in HW, a smarter SPI in HW (properly buffered), and Timers/Interrupts enough to support a few more UARTs at 19K2. Do you need full duplex, or half duplex ? -jg
Reply by ●February 14, 20062006-02-14
In article <DsidnQmpQ_oRwWzeRVn-rw@forethought.net>, donald@dontdoithere.com says...> Mark Borgerson wrote: > > > In article <4NydnUPsMpJ9rWzeRVn-iQ@giganews.com>, v2epl3e02 > > @sneakemail.com says... > > > >>Hi, > >> > >>Hoping I can benefit from the collective wisdom of the folks on this > >>newsgroup. > >> > >>What I am looking for is a simple UART / serial / RS-232 interface (I know > >>those terms aren't interchangeable), with minimum cost being the goal. > >> > >>The product sales will be in the 50k unit range annually, and the selling > >>price won't be very high at all a few 10s of dollars, if not cheaper. The > >>difference between a $1.50 chip and a $0.50 solution becomes pretty > >>significant. > >> > >>Basically I need to add 2 more serial interfaces and the microcontroller > >>only has 1 on-chip (i.e. need to go from 1 serial interface to 3). The 2 > >>new serial interfaces (added to a legacy product) will run 19200 baud, > >>N-8-1. > >> > >>I don't fancy hardware flow control, BREAK detection, etc... just RX, TX > >>and GND on the serial side. On the side interfacing to the > >>microcontroller, almost anything is fine (8-bit parallel, SPI, I2C, > >>whatever......) -- preferably with an interrupt line running to the micro > >>saying "I have a byte". > >> > >>No FIFO/buffering is needed, the micro can respond quickly to an > >>interrupt, but there isn't enough remaining CPU horsepower to implement 2 > >>software UARTs. Issues like framing errors, parity errors, etc... can > >>just discard the data and not bother the micro. > >> > >>Ultimately, I'd like a piece of silicon that says "Got another byte for > >>you, come get it". On the transmit side, I just want to "write" a byte to > >>the solution, whatever the interface, and know that the byte is going to be > >>shifted out at 19200. Higher level protocols will handle dropped bytes in > >>either direction. > >> > >>From a silicon standpoint, I don't care if it's one chip with the 2 UARTs, > >>or 2 pieces of duplicate technology (actually 2 single-UART pieces would be > >>ideal in the sense that another design might only need 1 additional "UART) > >> > >>So, is the best solution a tiny micro with someone's firmware? A PLD? > >>Something else? > >> > >>I'm looking for something ready to go, i.e. I could implement this on any > >>number of micros, as could most people here, but I need cheap and > >>ready-to-go. > >> > >>I hope I've provided enough information, I've tried to anticipate > >>questions out of respect for those kind enough to help out. > >> > >>All the best & thanks again. > > > > > > > > 2 x Max3100 SPI UARTS. > > Digikey has these for 3.25/2500 pcs. > Maxim-ic.com has them for 2.79 for 1K up. > > But you would need two. > > A single chip cpu bit banged can do 19200, even on two or three ports. > > Finding the right cpu would be a challange. > > > > > > CPLD or programmable logic---but watch out for the engineering cost > > at 50,000 units (Unless your're proud of working cheap). > > The engineering cost is the same for one or 50K. > > Once the software/vhdl is written, the next 49,999 is free.Yes, but if writing the VHDL takes too long, it could easily add $1 per unit to the cost for 50,000 units. Add the cost of the part and the labor to program it, and might be better to use a $3 UART. I have one peripheral board that requires two programming steps: the first to program the CPLD, and the second to program the vendor ID and serial number into the USB part. This is, by far, my most expensive board to produce, although no single part costs more than $6 (in very small quantities). In contrast, some boards with $45 A/D converters take no programming, but a few minutes to test, and take less of my time to manufacture. If I sold more than a few hundred per year, it would make sense to spend my time on consulting and hire some $15/hour labor to build these boards. As it is, I'm in that difficult in-between stage. At 50,000 boards, you are just shifting the price points, not eliminating the cost of labor.> > > > > > > Small At91SAM7 using two UARTs for external comms and one to > > communicate with main MPU via spi. > > > > > > If you already have an external data bus for RAM or FLASH, find > > another chip select and use a real UART (ST16C654 is the one I use). > > TI's version is 2.80/1k. > http://focus.ti.com/docs/prod/folders/print/tl16c752b.html > > > > > > > A bit more information about the main processor and system > > would be helpful. > > Yes, that would be good. > > > > > When it gets down to programming an MPU or CPLD, receiving > > is MUCH more difficult thanb transmitting. > > Depends on the cpu and how effecient is runs code.No matter how efficient the CPU, receiving and decoding asynchronous input is a more difficult programming task than transmitting data whare your processor sets the timing.> > The Op said he could write this himself, so could many here ( even me :-). > > But he was hoping to get it right away. > > Good Luck. > > donald > > PS: as they say, timing is everything.Even more so when you have to do more than one thing at a time! Mark Borgerson>
Reply by ●February 14, 20062006-02-14
> > > Small At91SAM7 using two UARTs for external comms and one to > communicate with main MPU via spi. > >Yes, the AT91SAM7 are a good candidate, but why not use the debug UART instead of the SPI. The debug UART is a normal UART except the hardware flow control lines which aren't needed anyway.
Reply by ●February 14, 20062006-02-14
I'll jump into the discussion and add my comments down the lines:> > >>The product sales will be in the 50k unit range annually, and theselling> > >>price won't be very high at all a few 10s of dollars, if not cheaper.The> > >>difference between a $1.50 chip and a $0.50 solution becomes pretty > > >>significant.I think this basically rules out any UART chip. Go for a cheap $0.50 micro doing one or two software uarts and host communication through SPI.> > Digikey has these for 3.25/2500 pcs. > > Maxim-ic.com has them for 2.79 for 1K up.Too expensive.> Yes, but if writing the VHDL takes too long, it could easily add > $1 per unit to the cost for 50,000 units. Add the cost of the > part and the labor to program it, and might be better to use > a $3 UART.If you need $50.000 to develop a UART in VHDL, you should find a new occupation.:-) VHDL UARTS can be found free on the net....> > > Small At91SAM7 using two UARTs for external comms and one to > > > communicate with main MPU via spi.Indeed. Or even an ATTiny. I have a product that does 4 UART (RX only, including 4 fifo's) at 4800 baud on an ATMega162 @8MHz. This takes up about 50% of the processing time max. I guess it should be possible to two TX/RX uarts at 19k2. You have to sample 4 times the bittime, so your timer interrupt would have to run at 76800 kHz. This gives you 13 us processing time for both uarts. Still tight. My soft-uart needs 26us max. for four channels receiving and one channel transmitting. The longest time is when a complete byte is received and it has to go into a fifo, which takes some time to calculate the pointers, fifo-full etc. I guess if you can stuff the byte out on the SPI immediately you can do it. Meindert
Reply by ●February 14, 20062006-02-14
On Monday, in article <4NydnUPsMpJ9rWzeRVn-iQ@giganews.com>
v2epl3e02@sneakemail.com "CBodd" wrote:
.....
>What I am looking for is a simple UART / serial / RS-232 interface (I know
>those terms aren't interchangeable), with minimum cost being the goal.
>
>The product sales will be in the 50k unit range annually, and the selling
>price won't be very high at all a few 10s of dollars, if not cheaper. The
>difference between a $1.50 chip and a $0.50 solution becomes pretty
>significant.
So what power rails, level conversion and connectors will have a big
impact as well, probably a bigger impact.
>Basically I need to add 2 more serial interfaces and the microcontroller
>only has 1 on-chip (i.e. need to go from 1 serial interface to 3). The 2
>new serial interfaces (added to a legacy product) will run 19200 baud,
>N-8-1.
Which microprocessor are you currently using?
What sort of power is currently available? e.g. 3V or 5V or both?
>I don't fancy hardware flow control, BREAK detection, etc... just RX, TX
>and GND on the serial side. On the side interfacing to the
>microcontroller, almost anything is fine (8-bit parallel, SPI, I2C,
>whatever......) -- preferably with an interrupt line running to the micro
>saying "I have a byte".
My alternative would be either put a second cheap micro on, or use a
different micro with at least 3 UARTs on already.
The problem is without knowing what your legacy micro is doing, could
make hardware interfacing awkward as in the old Intel/Motorola parallel
timing issues for parallel, what max SPI speed is achievable.
Do you only have 5V available as power (and how much spare)?
>No FIFO/buffering is needed, the micro can respond quickly to an
>interrupt, but there isn't enough remaining CPU horsepower to implement 2
>software UARTs. Issues like framing errors, parity errors, etc... can
>just discard the data and not bother the micro.
What micro family are you using already?
>Ultimately, I'd like a piece of silicon that says "Got another byte for
>you, come get it". On the transmit side, I just want to "write" a byte to
>the solution, whatever the interface, and know that the byte is going to be
>shifted out at 19200. Higher level protocols will handle dropped bytes in
>either direction.
>
>From a silicon standpoint, I don't care if it's one chip with the 2 UARTs,
>or 2 pieces of duplicate technology (actually 2 single-UART pieces would be
>ideal in the sense that another design might only need 1 additional "UART)
If cost is the issue then you need one piece of SMALL silicon to do TWO
UARTs as two pieces of silicon will increase the cost of PCB area on such
a tight budget. As well as how you interface to the legacy product as this
mean some PCB area will be needed for connections to that.
Where are the connectors for the UART I/O going to be and what size will
effect PCB area as well.
>So, is the best solution a tiny micro with someone's firmware? A PLD?
>Something else?
Extra micro or PLD may well be outside your price budget, and does the
budget include any necessary level converters and connectors?
>I'm looking for something ready to go, i.e. I could implement this on any
>number of micros, as could most people here, but I need cheap and
>ready-to-go.
My first port of call in this situation is the smallest cost increment
is most likely to be using another micro in the same family with more UARTS
built-in.
This also has the less hassle on interfacing at the hardware and software
levels.
Recently looked at a design and the best fit was a mico with 5 UARTs in.
If adding a micro I would consider adding a small H8 or H8S with lots
of internal UARTs in (2 or 3 is common across the families).
Alternatively some of the Rabbit or Z80 or other processors.
I have no idea on the 50K breaks on any of these.
My biggest worries on adding to legacy products are usually
a) how much power is available at what levels
That can be supplied by the legacy system guaranteed
Just hope that no extra filtering on power is required.
b) how do the mechanics work
(placement, volume constraints, other restrictions)
c) hardware and software interfacing
I have seen some nightmares where something simple got screwed up, due to
funny shape boards to fit in areas, or labour intensive to wire in, or the
actual margin of extra power available was marginal at best.
Any solution offered has the problem of insufficient power will scupper it.
All sorts of solutions have different power requirements that may or may
not work in your situation or the application (e.g. drains battery too quick).
>I hope I've provided enough information, I've tried to anticipate
>questions out of respect for those kind enough to help out.
>
>All the best & thanks again.
>
>
>
--
Paul Carpenter | paul@pcserviceselectronics.co.uk
<http://www.pcserviceselectronics.co.uk/> PC Services
<http://www.gnuh8.org.uk/> GNU H8 & mailing list info
<http://www.badweb.org.uk/> For those web sites you hate
Reply by ●February 14, 20062006-02-14
In article <43f1868f$0$47030$edfadb0f@dread15.news.tele.dk>, no@no.no says...> > > > > > Small At91SAM7 using two UARTs for external comms and one to > > communicate with main MPU via spi. > > > > > > Yes, the AT91SAM7 are a good candidate, but why not use the debug > UART instead of the SPI. The debug UART is a normal UART except > the hardware flow control lines which aren't needed anyway. >With the simple addition of a clock line from master to slave, you can transfer data at up to 25Mbits/second---many times the rate that you can achieve with a UART in asynchronous mode. Mark Borgerson
Reply by ●February 14, 20062006-02-14
First of all, thanks to *everyone* who replied... lots of very on-point and specific suggestions & thoughtful questions. Outstanding & much appreciated. In an attempt to detail my specific problem, I think I neglected to give a "big picture" view of the project, so hopefully I can fill in some details. Hopefully I addressed everyone's questions (if not -- I'm sorry, I didn't neglect anyone or any question intentionally). This is a currently-shipping product, based on a Samsung ARM7 chip (the nomenclature of the silicon has changed 3x since we've been using it in '99 -- something like S3C341x or whatever.... my databook is in the lab right now...) The ARM is running at 20 MHz and is at 80-85% CPU utilization (using uC/OS-II, the CPU pct loading is an optional feature that can be enabled, i.e. I'm pulling the figure out of my you-know-what) Anyway -- this part will be familiar to many of you -- cost, and secondly time to market are paramount here. There are many newer processors out there that have several integrated UARTs, etc... but the hit we'd take right now on re-doing this legacy board, drivers, etc... for a new processor (not to mention the manufacturing steps) would most likely be too much. We have the real estate & power budget to "glue on" the serial interfaces, but to swap out the processor in the short term has been ruled out (I'm often saying to the higher ups, "Do you want to pay know or pay later..." but we've all been there in the trenches & know how that goes) One of our primary customers has added functionality to the device we interface to, and requires us to supply two more RS232 ports on our product (DB9 connector on our side, RS232 levels coming into the board are +/- 5V, we just use transistors between the DB9 and the processor instead of a true level shifter IC to get 0 and 3.3V at the Samsung). We need full-duplex for this product. It's been a while since I did programmable logic, but if necessary that route is an option. I was thinking a small uC might be the best route, and several of the posts here don't dissuade me. We have a few unused GPIOs, a SPI bus that is not very heavily used, same for the I2C bus, a couple of unused interrupt lines as well. We have 1.8, 3.3, and 5V supplies, and no problems/issues with current or power levels. When my boss (one foot in mgmt, one foot in tech) looked for UARTs, he was shocked at the price per chip, and of course was upset that there wasn't a "simple" or "basic" UART (we don't need DTR, CTS, RTS, buffers/FIFOs, etc...) The cost margins on this are pretty tight already, and as you can imagine at large volumes, a $2 difference is pretty significant (we're a small company, and unfortunately the engineers' time [mine included] is often considered secondary to the BOM & manufacturing cost.) I don't have hard #s but I suspect that a $3.50-$4 vs $1 solution (assuming that's even possible) has a pretty signficant impact on the product's profitability. The mythical $1 price that I keep alluding to is primarily BOM cost for the silicon -- we don't need level shifters & we get the DB9s at something like 2 cents each and my time (NRE) is unfortunately not factored in. Hopefully that gives more insight into the product & my situation. Thanks again very much -- I'll keep checking back for more responses. And hopefully others will be able to benefit from this as well. P.S. Original title of my post was "Need low-cost serial interface or "UART" " but it was truncated when posting.... thanks for reading into the post in spite of the non-specific title!
