MultiUART is it easily possible?

Started by zhulien, 14:03, 03 March 21

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zhulien

We are getting a lot of CPC hardware with a UART so we can plugin the various modules available.  MP3, Click2Speech, Wifi, RTC, Temperature Control...


Would it be hard and would someone want to make a single multi-UART card so that many of these devices can be plugged in at once and used instead of on each card?  Perhaps an 8-UART card could be possible and workable on an M4?  A 6-UART could perhaps fit nicely, 1 each out the sides of an Mx card and 4 along the top if they fit? (2 facing forward, 2 facing backward?)...  From a CPC point of view, perhaps they can be multiplexed to send them commands but all controlled from a microcontroller on board without multiplexing to the actual UART.

GUNHED

Quote from: zhulien on 14:03, 03 March 21
We are getting a lot of CPC hardware with a UART so we can plugin the various modules available.  MP3, Click2Speech, Wifi, RTC, Temperature Control...
The LambdaSpeak (III or FS) expansion does already contain all that.  :)

Quote from: zhulien on 14:03, 03 March 21
Would it be hard and would someone want to make a single multi-UART card so that many of these devices can be plugged in at once and used instead of on each card?  Perhaps an 8-UART card could be possible and workable on an Mother X4?  A 6-UART could perhaps fit nicely, 1 each out the sides of an Mx card and 4 along the top if they fit? (2 facing forward, 2 facing backward?)...  From a CPC point of view, perhaps they can be multiplexed to send them commands but all controlled from a microcontroller on board without multiplexing to the actual UART.
Great idea! It would be nice to have an expansion with for 5V serial ports and four 12V RS232 ports. Not for adding all that devices, but for connecting a bunch of CPCs. Or for connecting few CPC-LANs.


You would love that on the next meeting you attend.  :) :) :)
http://futureos.de --> Get the revolutionary FutureOS (Update: 2022.03.09)
http://futureos.cpc-live.com/files/LambdaSpeak_RSX_by_TFM.zip --> Get the RSX-ROM for LambdaSpeak :-) (Updated: 2021.12.26)

Bryce

Quote from: GUNHED on 20:34, 03 March 21
The LambdaSpeak (III or FS) expansion does already contain all that.  :)
Great idea! It would be nice to have an expansion with for 5V serial ports and four 12V RS232 ports. Not for adding all that devices, but for connecting a bunch of CPCs. Or for connecting few CPC-LANs.


You would love that on the next meeting you attend.  :) :) :)

What's the advantage of having a 12V RS232? Most modern RS232 will be happy with 5V, only very old RS232 devices would need 12V. Are there any devices of that type that people would still want to connect to a CPC?

Bryce.

GUNHED

Quote from: Bryce on 11:17, 04 March 21
What's the advantage of having a 12V RS232? ... Are there any devices of that type that people would still want to connect to a CPC?
Bryce.
You gave the answer by yourself. The 12V feature is great for conntecting to CPCs with Amstrad RS232, Schneider RS232, Valcom, SCI, .... and way more.

And why should I use such an old device?
Well, to be able to connect to more than one other computer, this way being able to form a network.

And why do I need a network?
Go, ask the PC guys.  ;D
http://futureos.de --> Get the revolutionary FutureOS (Update: 2022.03.09)
http://futureos.cpc-live.com/files/LambdaSpeak_RSX_by_TFM.zip --> Get the RSX-ROM for LambdaSpeak :-) (Updated: 2021.12.26)

Bryce

Quote from: GUNHED on 16:10, 04 March 21
You gave the answer by yourself. The 12V feature is great for conntecting to CPCs with Amstrad RS232, Schneider RS232, Valcom, SCI, .... and way more.

And why should I use such an old device?
Well, to be able to connect to more than one other computer, this way being able to form a network.

And why do I need a network?
Go, ask the PC guys.  ;D

Ok. I was assuming that both (all) CPC's would then be using the new 4x UART expansion, not original RS232 expansions.

Bryce.

GUNHED

Quote from: Bryce on 16:19, 04 March 21
Ok. I was assuming that both (all) CPC's would then be using the new 4x UART expansion, not original RS232 expansions.
Bryce.
Like usually it depends on the final price of the unit. Also I think it's kind of friendly to have a possibility to 'get older expansions into the boat' too.


However, I'm just thinking in letters here. Whoever will build such an neat expansion will decide all that stuff anyway.
http://futureos.de --> Get the revolutionary FutureOS (Update: 2022.03.09)
http://futureos.cpc-live.com/files/LambdaSpeak_RSX_by_TFM.zip --> Get the RSX-ROM for LambdaSpeak :-) (Updated: 2021.12.26)

Bryce

That's why I asked. Adding the 12V feature would be a major expense.

Bryce.

GUNHED

Good point. In this case we still have the cheap level converters from the internet.
http://futureos.de --> Get the revolutionary FutureOS (Update: 2022.03.09)
http://futureos.cpc-live.com/files/LambdaSpeak_RSX_by_TFM.zip --> Get the RSX-ROM for LambdaSpeak :-) (Updated: 2021.12.26)

PulkoMandy

Why do people always want to put microcontrollers on their cards?


It is easy to find multi-UART chips that would work fine for this. Dual or quad UARTs are common.


For example you could use this for 8 channels: https://www.maxlinear.com/product/interface/uarts/8-bit-vlio-uarts/xr16l788


Or this for 4 channels (with an easier to use component package): https://www.maxlinear.com/product/interface/uarts/8-bit-vlio-uarts/st16c554d

VintageAdvantage

#9
Quote from: PulkoMandy on 14:58, 05 March 21Why do people always want to put microcontrollers on their cards?

This is probably a rhetorical question, but for the sake of others:

1. without microcontroller, no complex behavior
2. without microcontroller, no firmware
3. without microcontroller, the CPC has to have a (complex) driver
4. without microcontroller, certain types of expansion cards aren't even feasible at all. Examples of such include SF3, M4, LS3, USIfAC II, ...
5. without microcontroller, things are getting complicated
6. without microcontroller, things are getting expensive
7. without microcontroller, no flexibilty, no upgradability, and no expandabilty 

A microcontroller with 4 UARTs is 5 $ these days...

Hooking up a UART chip like this to the CPC is useless, because without on-card buffered interface (= microcontroller firmware) you won't be able to take advantage of BAUD rates higher than, say, 9600 BAUDs... the CPC won't be able to keep up with it anyhow.
There is an old saying - move the code, not the data. That means: do the processing locally, on the expansion card, in this case. Which requires a high speed MCU with some on-board SRAM that can provide an intelligent interface to the CPC then.

Having said that, most interesting "little breakout boards" either use SPI or I2C, not UART.

PulkoMandy

The uart in Albireo has hardware flow control and 544 bytes buffers in each direction, and no microcontroller. And it can run faster than the z80 can read data from it (not a problem because of the flow control)


You don't need the expansion board to include a faster cpu than the cpc for this. And the interface is simple: aport to know if data is available, and a port to read the data (and the opposite for the sending direction). I don't see how adding a separate microcontroller can make things simpler or cheaper here. There are not many ways to control an uart anyway...

gerald

Quote from: VintageAdvantage on 02:04, 06 March 21
This is probably a rhetorical question, but for the sake of others:
...
The real question is:When does the CPC merely becomes the microcontroller's keyboard / screen interface ?
If a CPC cannot cope with a single high speed UART why would you add more than one ?  If the intend is to do all the processing on a microcontroller, what's the use of the CPC ?

Would you say that a CPC can play 4k video with the help of a Raspberry Pi coprocessor ? or rather that the CPC is just a keyboard to the raspberry ?

GUNHED

#12
Quote from: VintageAdvantage on 02:04, 06 March 21
3. without microcontroller, the CPC has to have a (complex) driver
From a programmers perspective that is a _very_ important point.  :)


Quote from: gerald on 10:47, 06 March 21The real question is:When does the CPC merely becomes the microcontroller's keyboard / screen interface ?If a CPC cannot cope with a single high speed UART why would you add more than one ?  If the intend is to do all the processing on a microcontroller, what's the use of the CPC ?

There's not only black and white. :)
http://futureos.de --> Get the revolutionary FutureOS (Update: 2022.03.09)
http://futureos.cpc-live.com/files/LambdaSpeak_RSX_by_TFM.zip --> Get the RSX-ROM for LambdaSpeak :-) (Updated: 2021.12.26)

VintageAdvantage

#13
Quote from: gerald on 10:47, 06 March 21
The real question is:When does the CPC merely becomes the microcontroller's keyboard / screen interface ?
If a CPC cannot cope with a single high speed UART why would you add more than one ?  If the intend is to do all the processing on a microcontroller, what's the use of the CPC ?

Would you say that a CPC can play 4k video with the help of a Raspberry Pi coprocessor ? or rather that the CPC is just a keyboard to the raspberry ?
But that's how it is, no? For example, WIFI in the M4... all of the real stuff is handled by the little ESP32 on board, none of this WIFI stuff is done by the CPC... and it would be infeasible. Not to mention that the ESP is hosting all of the M4 Webserver interface! Would you want to do this on the CPC? Come on...

Still, we love WIFI on the CPC, don't we? Of course it is still the CPC we care about, what's the point of creating these expansions otherwise? Should we not have WIFI on the CPC only because the CPC couldn't do it in Z80 bare metal? I don't think so.

Well, you could say - get one of these UART Wifi modules and connect it to the old RS232  :P But that would be slooowwww...

And remember that even the ARM was developed back in the day with a BBC Micro / Master system, using the tube... so, even if the Acorn was only used as a host for the co-processors, it still made all the difference 
So does the M4 for the CPC.  :D
Also, previous CPC hardware designs (not mentioning any here...) have shown how difficult it is to recover from hardware design flaws without the microcontroller flexibilty...

So, yeah, having 4K on the CPC is as valid as having WIFI in the M4 on the CPC. Good point!

Besides, people are using their cell phones to upload games to the CPC... that's invalid as well then, get a real tape  8) The phone is a supercomputer compared to the CPC  ;D
I see an interesting weekend discussion emerging here  :laugh:

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