On Thu, 31 Dec 2020 21:41:51 +0100, RobertoA wrote:

> Il 30/12/2020 19:31, Martin Gregorie ha scritto:
>> On Wed, 30 Dec 2020 16:19:56 +0100, RobertoA wrote:
>>
>>> The Raspberry4 board has 6 native uart I'm not talking about serial
>>> ports via usb but uart on the gpio connector of the Raspberry board
>>> Having to control devices via uart (for example gps receivers,
>>> electronic scales, etc.) it would be useful to create a device that,
>>> communicating with the control computer via ethernet, would allow the
>>> computer to 'see' the virtual com ports, corresponding to the uart of
>>> the card Raspberry So it will be necessary to program the Raspberry so
>>> that it has a tcp /
>>>
>> Ignore the gpio lines: Just get a standard a USB-serial adapter. Each
>> supports a single serial line, so get one for each device with a serial
>> port that you need to connect to the Pi and either plug them directly
>> into the Pi or, if you run out of USB ports, via a USN connector block.
>>
>> The ones I've used have all presented a common interface to Linux:
>> plugging one in on a Pi automatically creates a new serial device,
>> /dev/ ttyUSBnn IIRC, that behaves exactly like one of the predefined
>> serial ports (/dev/ttynn) that are created at boot time on a PC with
>> builot-in serial ports. This means that any program using the standard
>> Linux serial port library routines can read and write to anything
>> connected to your Pi via a USBserial adapter. It can also set the baud
>> rate, character size, parity and stop bits.
>>
>> The last Serial USB adapter I bought came from PicAxe, where they're
>> used to upload PIC binaries to a PICAXE chip and/or to let the program
>> you uploaded to the PICAXE chip talk to a program on your Linux box.
>> They work just fine if that's a Pi too.
>>
>> PICAXE http://www.picaxe.com/ sell adaptors for £12.49 (VAT incl) +
>> postage:
>>
>> https://picaxe.com/hardware/cables/picaxe-usb-download-cable/
>>
>>
>> I'm certain they're available elsewhere too, but that's where I bought
>> the last one I needed.
>>
>>
> Why ignore the uarts provided on the gpio connector?

Because a USB serial adapter is ready to run off the shelf and uses
standard RS-232 levels, character encoding, parity and stop bits on its
serial side, which is compatible with most items with serial connections,
e.g. puck-type GPS receivers.

The ones sold by PICAXE have the USP blug on the body with a serial cable
terminated by a 3.5mm 3-wire jackplug. Most other converters seem to come
with a D9 socket (male or female - you choose) on the converter body and
the USB plug on a short flying lead. Amazon has loads of them in the £7 -
£15 price range.



--
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Martin    | martin at
Gregorie  | gregorie dot org

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