[EE] Using a microcontroller as a peripheral?

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[EE] Using a microcontroller as a peripheral?

Neil Cherry-3
Does anyone have an example of using a microcontroller as a peripheral chip?

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Re: [EE] Using a microcontroller as a peripheral?

James Cameron-2
Chirp! - the plant watering alarm, is both a device that can work
alone, and also provides I2C so as to act as a peripheral.

https://wemakethings.net/chirp/

On Mon, Oct 05, 2020 at 01:09:33AM -0400, Neil Cherry wrote:

> Does anyone have an example of using a microcontroller as a peripheral chip?
>
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Re: [EE] Using a microcontroller as a peripheral?

madscientistatlarge
In reply to this post by Neil Cherry-3
Hard drives, anything usb, and most other peripherals have their' own microcontroller/system-on-a-chip (keyboard/mouse). Mother boards also have a small micro that handles controlling the power supply and possibly other house cleaning.  Any modern printer/plotter (I've seen ancient printers that use the system cpu for everything back in the s100 days). And obviously any "Smart Home" device being controlled by another computer.

It depends on what you consider "a peripheral chip", i.e. embedded and controlled by an external cpu, or do you mean using as a peripheral for some special function (like the soft power control on motherboards).  Do you include things like ethernet cards that handle checksums/encryption to unload the main cpu?  And of course the PIC microcontrollers were originally for I/O expansion of other micros or possibly larger systems with a higher end cpu?  Burglar alarms with central monitoring would also likely be included if they are not ancient (I.E. the burglar/fire alarm has a micro, and the Monitoring station uses desktops and/or servers for the monitoring).


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On Sunday, October 4, 2020 11:09 PM, Neil Cherry <[hidden email]> wrote:

> Does anyone have an example of using a microcontroller as a peripheral chip?
>
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Re: [EE] Using a microcontroller as a peripheral?

David Van Horn
In reply to this post by Neil Cherry-3
Periperal Interface Controller is indeed how PIC started, if I remember correctly.

________________________________
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Sent: Sunday, October 4, 2020 11:09 PM
To: Microcontroller discussion list - Public. <[hidden email]>
Subject: [EE] Using a microcontroller as a peripheral?

Does anyone have an example of using a microcontroller as a peripheral chip?

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Re: [EE] Using a microcontroller as a peripheral?

David C Brown
In the old mainframe days a peripheral was a device which was not part of
the core CPU/Memory unit, such as a printer, magnetic tape deck, etc.
A device was needed to interface to the peripheral and originally that
would be a custom design made of TTL chips.  When small single chip
processors became available they were used instead.  And the early PICS
were squarely aimed at that market, hence the name.
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On Mon, 5 Oct 2020 at 09:07, David Van Horn <
[hidden email]> wrote:

> Periperal Interface Controller is indeed how PIC started, if I remember
> correctly.
>
> ________________________________
> From: [hidden email] <[hidden email]> on behalf of Neil
> Cherry <[hidden email]>
> Sent: Sunday, October 4, 2020 11:09 PM
> To: Microcontroller discussion list - Public. <[hidden email]>
> Subject: [EE] Using a microcontroller as a peripheral?
>
> Does anyone have an example of using a microcontroller as a peripheral
> chip?
>
> --
> Linux Home Automation         Neil Cherry       [hidden email]
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Re: [EE] Using a microcontroller as a peripheral?

Jason White-20
Used a separate PIC for DSP functions doing FFT (among other things) on
incoming signals and reporting the results via SPI. Just was easier to
"have another core" and to split the codebase into two parts.

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Re: [EE] Using a microcontroller as a peripheral?

Clint Jay
Many times, they're used in server PSUs, hard drive backplanes, I've seen
them on control panels for servers, battery packs for storage arrays.

On Mon, 5 Oct 2020 at 11:47, Jason White <[hidden email]>
wrote:

> Used a separate PIC for DSP functions doing FFT (among other things) on
> incoming signals and reporting the results via SPI. Just was easier to
> "have another core" and to split the codebase into two parts.
>
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Re: [EE] Using a microcontroller as a peripheral?

Neil Cherry-3
In reply to this post by madscientistatlarge
On 10/5/20 1:56 AM, madscientistatlarge wrote:

> It depends on what you consider "a peripheral chip", i.e. embedded and controlled by an
> external cpu, or do you mean using as a peripheral for some special function (like the
> soft power control on motherboards).  Do you include things like ethernet cards that
> handle checksums/encryption to unload the main cpu?  And of course the PIC
> microcontrollers were originally for I/O expansion of other micros or possibly larger
> systems with a higher end cpu?  Burglar alarms with central monitoring would also
> likely be included if they are not ancient (I.E. the burglar/fire alarm has a micro,
> and the Monitoring station uses desktops and/or servers for the monitoring).

My apologies, I did make that way too vague. Let me add specifics. I want to use a PIC32
as a peripheral chip like an 8255 and a 6850 and interfacing that to an existing
microprocessor chip as a 6502, 6809 or Z180. I happen to have these boards, which is
why I'm selecting these. This would be a parallel, 8 bit interface with addressing
and control for accessing registers. I'm trying not to rewrite the firmware on
these old boards.

And yes I do see the irony of taking a chip infinitely more powerful than the main
CPU and turning it into a peripheral. But I want to start off with simple (the
8255) and work to more complex (video chips) which really need to connect to HDMI
now.

Oh, this is a side project. Not something for work.

So far my Search-fu has me running running into the peripherals of the MCU not
the MCU a peripheral of the CPU.

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Re: [EE] Using a microcontroller as a peripheral?

Alan Pearce
Just been looking into this myself. Check out the enhanced mode of the
parallel master port. That allows 4 addressable locations that make up
one 32 bit word inside the PIC32. it is described quite succinctly in
the FRM chapter.

On Mon, 5 Oct 2020 at 13:22, Neil Cherry <[hidden email]> wrote:

>
> On 10/5/20 1:56 AM, madscientistatlarge wrote:
>
> > It depends on what you consider "a peripheral chip", i.e. embedded and controlled by an
> > external cpu, or do you mean using as a peripheral for some special function (like the
> > soft power control on motherboards).  Do you include things like ethernet cards that
> > handle checksums/encryption to unload the main cpu?  And of course the PIC
> > microcontrollers were originally for I/O expansion of other micros or possibly larger
> > systems with a higher end cpu?  Burglar alarms with central monitoring would also
> > likely be included if they are not ancient (I.E. the burglar/fire alarm has a micro,
> > and the Monitoring station uses desktops and/or servers for the monitoring).
>
> My apologies, I did make that way too vague. Let me add specifics. I want to use a PIC32
> as a peripheral chip like an 8255 and a 6850 and interfacing that to an existing
> microprocessor chip as a 6502, 6809 or Z180. I happen to have these boards, which is
> why I'm selecting these. This would be a parallel, 8 bit interface with addressing
> and control for accessing registers. I'm trying not to rewrite the firmware on
> these old boards.
>
> And yes I do see the irony of taking a chip infinitely more powerful than the main
> CPU and turning it into a peripheral. But I want to start off with simple (the
> 8255) and work to more complex (video chips) which really need to connect to HDMI
> now.
>
> Oh, this is a side project. Not something for work.
>
> So far my Search-fu has me running running into the peripherals of the MCU not
> the MCU a peripheral of the CPU.
>
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Re: [EE] Using a microcontroller as a peripheral?

Neil Cherry-3
On 10/5/20 8:30 AM, Alan Pearce wrote:
> Just been looking into this myself. Check out the enhanced mode of the
> parallel master port. That allows 4 addressable locations that make up
> one 32 bit word inside the PIC32. it is described quite succinctly in
> the FRM chapter.

Thanks, I don't think I've looked that up so far. :-)

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Re: [EE] Using a microcontroller as a peripheral?

David VanHorn-2
The modern PC will frequently have a graphics card which is vastly more
powerful than the CPU.
I ran software called XFDTD on an Nvidia Titan card, where a given sim
would complete in 5 or 6 hours, and without the graphics card, in 2 or 3
years.


On Mon, Oct 5, 2020 at 7:02 AM Neil Cherry <[hidden email]> wrote:

> On 10/5/20 8:30 AM, Alan Pearce wrote:
> > Just been looking into this myself. Check out the enhanced mode of the
> > parallel master port. That allows 4 addressable locations that make up
> > one 32 bit word inside the PIC32. it is described quite succinctly in
> > the FRM chapter.
>
> Thanks, I don't think I've looked that up so far. :-)
>
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Re: [EE] Using a microcontroller as a peripheral?

William Westfield
In reply to this post by Neil Cherry-3

> I want to use a PIC32 as a peripheral chip like an 8255 and a 6850 and interfacing that to an existing microprocessor chip as a 6502, 6809 or Z180.

See for example:
https://hackaday.io/project/19000-a-4-4ics-z80-homemade-computer-on-breadboard <https://hackaday.io/project/19000-a-4-4ics-z80-homemade-computer-on-breadboard>
https://hackaday.io/project/159973-z80-mbc2-a-4-ics-homebrew-z80-computer <https://hackaday.io/project/159973-z80-mbc2-a-4-ics-homebrew-z80-computer>

these use an ATmega32 as peripheral(s) and bootloader/frontPanelEquivalent for a Z80.
The same author has also done an 8088 and is working on a 68008 using similar techniques.

A microcontroller running software may not respond to memory/io handshaking signals from an old microcontroller fast enough to be reliable - the above projects use an external flipflop to insert as many wait states as needed (flip the processor into wait mode when the IO access is detected, have the uC flip it back once it’s put things on the bus.)  Some processors might have features that make this easier (Configurable logic, or … don’t some PICs have a “Parallel Master/Save Port”?)

BillW

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Re: [EE] Using a microcontroller as a peripheral?

James Cameron-2
BillW wrote:
> A microcontroller running software may not respond to memory/io
> handshaking signals from an old microcontroller fast enough to be
> reliable - the above projects use an external flipflop to insert as
> many wait states as needed (flip the processor into wait mode when
> the IO access is detected, have the uC flip it back once it’s put
> things on the bus.)

Fantastic.  Light dawns after 41 years.

I learned of the Z80 WAIT signal as a child, was puzzled why it
was unused on my TRS-80, and lacked an easy to understand method
of using it.  I remember seeing the 4k7 pullup to 5V, and that the
signal was exposed on the expansion connector.  Driving it low did
indeed stop everything, and my computer was fine afterwards.

Now it seems obvious how it could be used.

The TRS-80 technical manual was bed time reading for me.  Of this
particular signal it said (pause for ocrmypdf and tesseract ...)

"The WAIT input, pin 24 of Z40, will slow the CPU down if there are
slow memories it must access. If this line goes low, the CPU will go
into a wait status until it goes back high.  Once high, the CPU
continues with the operation. For example: Assume you have a memory
system that takes 100 microseconds before addressed data can be
guaranteed to be present at the output. When the memory logic sees
that the CPU wants data, it will make the WAIT line low.  At the end
of 100 microseconds time, the logic will make the WAIT pin high, and
the CPU will input the data."

I see the Z80-MBC schematic sets the 74HC00 flip-flop in response to
IORQ.  Therefore the IN and OUT I/O instructions.

And, now I see you ported the Forth.  Well done!

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Re: [EE] Using a microcontroller as a peripheral?

RussellMc
>
> > ... The TRS-80 technical manual was bed time reading for me.  ...


Memories.
Osborne 1 -  "An introduction to microcomputers" ~= 1976.

Adam Osborne papers collection - 9 page blackish hile for some:


https://archive.computerhistory.org/resources/access/text/finding-aids/102738362-Osborne/102738362-Osborne.pdf

     Russell
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Re: [EE] Using a microcontroller as a peripheral?

David C Brown
Still got that albeit the 1981 edition.
__________________________________________
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43 Bings Road
Whaley Bridge
High Peak                           Phone: 01663 733236
Derbyshire                eMail: [hidden email]
SK23 7ND          web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>



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On Tue, 6 Oct 2020 at 07:08, RussellMc <[hidden email]> wrote:

> >
> > > ... The TRS-80 technical manual was bed time reading for me.  ...
>
>
> Memories.
> Osborne 1 -  "An introduction to microcomputers" ~= 1976.
>
> Adam Osborne papers collection - 9 page blackish hile for some:
>
>
>
> https://archive.computerhistory.org/resources/access/text/finding-aids/102738362-Osborne/102738362-Osborne.pdf
>
>      Russell
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Re: [EE] Using a microcontroller as a peripheral?

David VanHorn-2
One Hundred Microseconds??   Wow. How far we have come.


On Tue, Oct 6, 2020 at 4:19 AM David C Brown <[hidden email]> wrote:

> Still got that albeit the 1981 edition.
> __________________________________________
> David C Brown
> 43 Bings Road
> Whaley Bridge
> High Peak                           Phone: 01663 733236
> Derbyshire                eMail: [hidden email]
> SK23 7ND          web: www.bings-knowle.co.uk/dcb
> <http://www.jb.man.ac.uk/~dcb>
>
>
>
> *Sent from my etch-a-sketch*
>
>
> On Tue, 6 Oct 2020 at 07:08, RussellMc <[hidden email]> wrote:
>
> > >
> > > > ... The TRS-80 technical manual was bed time reading for me.  ...
> >
> >
> > Memories.
> > Osborne 1 -  "An introduction to microcomputers" ~= 1976.
> >
> > Adam Osborne papers collection - 9 page blackish hile for some:
> >
> >
> >
> >
> https://archive.computerhistory.org/resources/access/text/finding-aids/102738362-Osborne/102738362-Osborne.pdf
> >
> >      Russell
> > --
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Re: [EE] Using a microcontroller as a peripheral?

Wouter van Ooijen
In reply to this post by RussellMc
Yes!

The good old  An Introduction to microcomputers - my bible when I was
20y old.

I hope to stumble upon a copy of the series on some 2nd-hand market one
day...

Op 06-Oct-20 om 8:07 AM schreef RussellMc:

>>> ... The TRS-80 technical manual was bed time reading for me.  ...
>
> Memories.
> Osborne 1 -  "An introduction to microcomputers" ~= 1976.
>
> Adam Osborne papers collection - 9 page blackish hile for some:
>
>
> https://archive.computerhistory.org/resources/access/text/finding-aids/102738362-Osborne/102738362-Osborne.pdf
>
>       Russell

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Re: [EE] Using a microcontroller as a peripheral?

Dave Tweed
In reply to this post by David VanHorn-2
David VanHorn wrote:
> One Hundred Microseconds?? Wow. How far we have come.

I think that even back then, that was a purely hypothetical example.

I don't think that there was ever any form of *electronic* memory that was
that slow -- even magnetic core memory cycles in a few microseconds. The
slowest chip memory I can think of (1702 EPROM) had an access time of 1 us.

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Re: [EE] Using a microcontroller as a peripheral?

David C Brown
In the early seventies II worked on a system using the Intel 1103 1k DRAM
chip.  It had a read cycle time of 580nS abvoyt twice as fast as core
memory but much cheaper -  a penny a bit.  (in those halcyon days a UK
penny was worth one US cent).

When I went for an interview with a government department they laughed out
loud when I said we were building a multi megabit dram system and said it
would never work.  It did but it was a difficult job.  By 1978 I was
building systems with 4K sciatica chips which were a joy to work with.
__________________________________________
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43 Bings Road
Whaley Bridge
High Peak                           Phone: 01663 733236
Derbyshire                eMail: [hidden email]
SK23 7ND          web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>



*Sent from my etch-a-sketch*


On Tue, 6 Oct 2020 at 17:43, Dave Tweed <[hidden email]> wrote:

> David VanHorn wrote:
> > One Hundred Microseconds?? Wow. How far we have come.
>
> I think that even back then, that was a purely hypothetical example.
>
> I don't think that there was ever any form of *electronic* memory that was
> that slow -- even magnetic core memory cycles in a few microseconds. The
> slowest chip memory I can think of (1702 EPROM) had an access time of 1 us.
>
> -- Dave Tweed
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>
--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist