Boxed MCU with RS-232 Port

On Friday, March 24, 2023 at 7:45:03 AM UTC-4, Hans-Bernhard Bröker wrote:
> Am 24.03.2023 um 09:02 schrieb Rick C: 
> > On Thursday, March 23, 2023 at 11:54:54 AM UTC-4, Paul Rubin wrote: 
> >> Rick C <gnuarm.del...@gmail.com> writes: 
> >>> If you are talking about someone to build a board, no thanks. 
> >> No, building a board would be crazy unless you're making 1000s of them. 
> >> Pick an Arduino or similar board with RS232 support, 
> > 
> > That's one of the problems. Boards like Arduinos do not have RS-232 support. They have serial ports, but that's what was tried initially, with a home brew RS-232 level shifter added on a perf board.
> Color me puzzled. Why on earth would anyone home-brew an RS232 level 
> shifter, particularly for a project that could clearly afford using 
> ready-made ICs like MAX232 instead?

That's what they used.  I simply meant it was not a commercial product on a PCB.  Half the units have some problem.  

Did you think I meant they designed their own level shifter chip? 

-- 

Rick C.

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On Friday, March 24, 2023 at 10:20:37 AM UTC-4, Theo wrote:
> Hans-Bernhard Br&ouml;ker <HBBr...@t-online.de> wrote: 
> > Am 24.03.2023 um 09:02 schrieb Rick C: 
> > > On Thursday, March 23, 2023 at 11:54:54&#8239;AM UTC-4, Paul Rubin wrote: 
> > >> Rick C <gnuarm.del...@gmail.com> writes: 
> > >>> If you are talking about someone to build a board, no thanks. 
> > >> No, building a board would be crazy unless you're making 1000s of them. 
> > >> Pick an Arduino or similar board with RS232 support, 
> > > 
> > > That's one of the problems. Boards like Arduinos do not have RS-232 
> > > support. They have serial ports, but that's what was tried initially, 
> > > with a home brew RS-232 level shifter added on a perf board. 
> > 
> > Color me puzzled. Why on earth would anyone home-brew an RS232 level 
> > shifter, particularly for a project that could clearly afford using 
> > ready-made ICs like MAX232 instead?
> The problem is that commercial microcontroller boards like Arduinos tend to 
> have TTL level serial ports (or USB ones). If you want a box holding one of 
> those with some RS232 ports, you need to make a PCB with a MAX232 and a DB9, 
> and an enclosure to match. Rick was trying to find a box with all that 
> already done for him and drew a blank. 
> 
> It's not the design that's the problem, it's the manufacturing. 
> 
> Although for quantity 20 at these kind of price points, I might be tempted 
> to build something using dev boards, eg: 
> https://www.dfrobot.com/product-1030.html 
> and maybe a bit of 3D printing for an enclosure. For two of those boards 
> you might need to hand-patch one to use different pins, but it's not hard 
> and could be done. 

This device is exactly what makes this difficult.  Which pin on the DB9 is the data output?  


> If the customer is willing to pay $300 a unit it might be worth Rick's (or 
> somebody else's) time to do it. I'll be happy to take that contract, email 
> address works :-) 

You will need to post an email address.  GG doesn't provide the email.  Just HBBr...@t-online.de

-- 

Rick C.

----+ Get 1,000 miles of free Supercharging
----+ Tesla referral code - https://ts.la/richard11209

On 22.03.2023 20:18, Rick C wrote:

 > I was skimming the web for this again and I think I found something from Aaeon.  Not sure why I didn't find this before.  Maybe I did, but at that time was really looking for something with a simple CPU, rather than something to run a full OS.  Beggars and choosers...
 >
 > https://eshop.aaeon.com/ultra-slim-box-pc-boxer-6405.html
 >
 > This one is $366, which is more than I'd like, but beggars...  It is cheaper than the tailored unit a guy is working on for us.  A sample unit doesn't work right and debugging across an ocean is not working very well.  I could have this up and running in a day or something, as long as it comes 
with Linux installed.


A lot of power consumption for such a task! An Atmel board
would only consume about 0.4 W, for example something like
that:

https://www.ledato.de/product_info.php?products_id=33
https://www.ledato.de/product_info.php?products_id=35

The price is crazy, but there should be similar
devices for only 1/5 of this price.

Rick C <gnuarm.deletethisbit@gmail.com> wrote:
> On Friday, March 24, 2023 at 10:20:37&#8239;AM UTC-4, Theo wrote:
> 
> This device is exactly what makes this difficult.  Which pin on the DB9 is the data output?  

TXD (output of MAX2323ESE) is pin 2, RXD (input of MAX2323ESE) is pin 3.

ie would connect to a PC via a straight-through cable, not a null modem.

> > If the customer is willing to pay $300 a unit it might be worth Rick's (or 
> > somebody else's) time to do it. I'll be happy to take that contract, email 
> > address works :-) 
> 
> You will need to post an email address.  GG doesn't provide the email.  Just HBBr...@t-online.de

My email is on the bottom of http://www.markettos.org.uk/

(I am in the UK, if that makes a difference)

Theo

On 24.03.2023 17:16, Herbert Kleebauer wrote:

> https://www.ledato.de/product_info.php?products_id=33
> https://www.ledato.de/product_info.php?products_id=35

The same company (ledato.de, taskit.de) has also an ARM
board with Ubuntu and 2 (or 3) RS232 ports which is cheaper:

https://www.taskit.de/produkte/flex-iot/
https://youtu.be/Fsr8F6B7j0s

Am 24.03.2023 um 16:03 schrieb Rick C:
> On Friday, March 24, 2023 at 7:45:03 AM UTC-4, Hans-Bernhard Bröker
> wrote:
>> Am 24.03.2023 um 09:02 schrieb Rick C:

>>> That's one of the problems. Boards like Arduinos do not have
>>> RS-232 support. They have serial ports, but that's what was tried
>>> initially, with a home brew RS-232 level shifter added on a perf
>>> board.

>> Color me puzzled. Why on earth would anyone home-brew an RS232
>> level shifter, particularly for a project that could clearly afford
>> using ready-made ICs like MAX232 instead?
> 
> That's what they used.  I simply meant it was not a commercial
> product on a PCB.  Half the units have some problem.
> 
> Did you think I meant they designed their own level shifter chip?

You said you home-brewed the level shifter.  How else was anybody to
interpret that?

Am 24.03.2023 um 15:20 schrieb Theo:

> The problem is that commercial microcontroller boards like Arduinos tend to
> have TTL level serial ports (or USB ones).  If you want a box holding one of
> those with some RS232 ports, you need to make a PCB with a MAX232 and a DB9,
> and an enclosure to match.  Rick was trying to find a box with all that
> already done for him and drew a blank.

Of course he did.  Finding that kind of box off-the-shelf was a very 
long shot, IMHO.

Industrialized versions of the Raspberry Pi might have come close, but 
they're more likely to offer RS485 or 422, insead of 232.

On Friday, March 24, 2023 at 12:17:17 PM UTC-4, Herbert Kleebauer wrote:
> On 22.03.2023 20:18, Rick C wrote: 
> 
> > I was skimming the web for this again and I think I found something from Aaeon. Not sure why I didn't find this before. Maybe I did, but at that time was really looking for something with a simple CPU, rather than something to run a full OS. Beggars and choosers... 
> > 
> > https://eshop.aaeon.com/ultra-slim-box-pc-boxer-6405.html 
> > 
> > This one is $366, which is more than I'd like, but beggars... It is cheaper than the tailored unit a guy is working on for us. A sample unit doesn't work right and debugging across an ocean is not working very well. I could have this up and running in a day or something, as long as it comes 
> with Linux installed.
> A lot of power consumption for such a task! An Atmel board 
> would only consume about 0.4 W, for example something like 
> that: 
> 
> https://www.ledato.de/product_info.php?products_id=33 
> https://www.ledato.de/product_info.php?products_id=35 
> 
> The price is crazy, but there should be similar 
> devices for only 1/5 of this price.

There should be many things in this world. 

Rick C <gnuarm.deletethisbit@gmail.com> writes:
> This device is exactly what makes this difficult.  Which pin on the
> DB9 is the data output?

The pinout is given here: https://wiki.dfrobot.com/RS232_Shield

How do you feel about using that board, with an Arduino?  Digikey stocks
it, if that helps:

https://www.digikey.com/en/products/detail/dfrobot/DFR0258/6588574

How do you feel about recycling the enclosure from one of those port
selector switches discussed a while back?

Here is a Lilygo board which has an ESP32-C3 MCU and RS232 among
other things, for $17.98:  https://www.lilygo.cc/products/t-rsc3

It is shipped from China so maybe doesn't fulfill requirements because
of that, but it at least shows that such a product exists.

Article about it with an Aliexpress redirect link (it is also sold
through there):

https://www.cnx-software.com/2023/01/20/lilygo-t-rsc3-esp32-c3-board-features-isolated-rs232-rs485-interfaces-5-to-24v-dc-input/

Direct Aliexpress

https://www.aliexpress.com/item/1005005136988162.html

Here is an Olimex MSP430 board with RS232 for around $32:

https://www.olimex.com/Products/MSP430/Starter/MSP430-5438-STK/

It is available at Mouser, though they only have 9 in stock right now:

https://www.mouser.com/ProductDetail/Olimex-Ltd/MSP430-5438STK?qs=BoUPAr39LHyy3j%2FN0eUzfQ%3D%3D

It is also on Digikey's site, but out of stock there.

There are more Olimex boards with RS232 that I didn't look up.

You mentioned that you didn't want to use an external FTDI cable on a
USB port.  What about having an FTDI dongle inside the box, installed so
that its DB9 connector is panel mounted?

https://ftdichip.com/products/usb-com232-plus1/
https://ftdichip.com/products/db9-usb-f/

TTL to RS232 (?): https://www.sparkfun.com/products/449
Similar: https://www.waveshare.com/wiki/RS232_Board

Regarding the locations: are any in the western US?

On Friday, March 24, 2023 at 4:42:55 PM UTC-4, Paul Rubin wrote:
> Rick C <gnuarm.del...@gmail.com> writes: 
> > This device is exactly what makes this difficult. Which pin on the 
> > DB9 is the data output?
> The pinout is given here: https://wiki.dfrobot.com/RS232_Shield 

You didn't answer the question.  Which pin is the data output and which is the data input?  


> How do you feel about using that board, with an Arduino? Digikey stocks 
> it, if that helps: 
> 
> https://www.digikey.com/en/products/detail/dfrobot/DFR0258/6588574 

Are you going to make the cable required? 


> How do you feel about recycling the enclosure from one of those port 
> selector switches discussed a while back? 

Recycling is not a problem, as long as there is no branding on the box. 


> Here is a Lilygo board which has an ESP32-C3 MCU and RS232 among 
> other things, for $17.98: https://www.lilygo.cc/products/t-rsc3 
> 
> It is shipped from China so maybe doesn't fulfill requirements because 
> of that, but it at least shows that such a product exists. 
> 
> Article about it with an Aliexpress redirect link (it is also sold 
> through there): 
> 
> https://www.cnx-software.com/2023/01/20/lilygo-t-rsc3-esp32-c3-board-features-isolated-rs232-rs485-interfaces-5-to-24v-dc-input/ 
> 
> Direct Aliexpress 
> 
> https://www.aliexpress.com/item/1005005136988162.html 
> 
> Here is an Olimex MSP430 board with RS232 for around $32: 
> 
> https://www.olimex.com/Products/MSP430/Starter/MSP430-5438-STK/ 
> 
> It is available at Mouser, though they only have 9 in stock right now: 
> 
> https://www.mouser.com/ProductDetail/Olimex-Ltd/MSP430-5438STK?qs=BoUPAr39LHyy3j%2FN0eUzfQ%3D%3D 
> 
> It is also on Digikey's site, but out of stock there. 
> 
> There are more Olimex boards with RS232 that I didn't look up. 
> 
> You mentioned that you didn't want to use an external FTDI cable on a 
> USB port. What about having an FTDI dongle inside the box, installed so 
> that its DB9 connector is panel mounted? 
> 
> https://ftdichip.com/products/usb-com232-plus1/ 
> https://ftdichip.com/products/db9-usb-f/ 

Are you going to write the USB stack to run on the simple CPUs you have linked to? 


> TTL to RS232 (?): https://www.sparkfun.com/products/449 
> Similar: https://www.waveshare.com/wiki/RS232_Board 

I don't know why you are showing all these devices.  

> Regarding the locations: are any in the western US?

I don't know.  Why does this matter?  You won't be visiting the customer's site. 

You seem to be thrashing around in looking at every little board that might or might not do the job, rather than finding one that will.  The single port boards you've identified have the DB9 connector, but you don't indicate how you will split this into the two connectors required for the job. 

Do you understand the requirements? 

-- 

Rick C.

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---+- Tesla referral code - https://ts.la/richard11209