Pi configuration

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bestm80eva
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Pi configuration

Postby bestm80eva » Mon May 29, 2017 9:46 pm

Is there any info on how the pi is connected to the next . ie the gpio pinouts is there a schematic of something?

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emook
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Re: Pi configuration

Postby emook » Mon May 29, 2017 11:16 pm

Victor said this "You can access anywhere... Any port or any ram. Remember you have A0-A15, D0-D7, /IOREQ, /MREQ, /RD and /WR. To map another 128k page, you listen for a write on port 0x7ffd and get the page on bit D0-D3. You can listen for ULA port and serve keyboard data. You can listen for kempston port and serve joystick data... and so..."

But we dont have what GPIO pin does what yet.
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Northernbob
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Re: Pi configuration

Postby Northernbob » Tue May 30, 2017 10:14 am


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Timbucus
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Re: Pi configuration

Postby Timbucus » Tue May 30, 2017 8:56 pm

There is a diagram included in the TK-PI documents that shows how the system is built and connected along with a copy of an older version of the bare metal OS so you can see how it works. The FPGA code is also there if you want to look at it:

https://gitlab.com/victor.trucco/TK-Pie

It's a shame that the NMI and HALT are not connected as the rPI0 could get up to some real tricks then...
I'm Infinite Imaginations when not in work... PAWS for thought.

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vtrucco
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Re: Pi configuration

Postby vtrucco » Tue May 30, 2017 9:54 pm

Timbucus wrote: Tue May 30, 2017 8:56 pm It's a shame that the NMI and HALT are not connected as the rPI0 could get up to some real tricks then...
Any signal can be available at Pi GPIO. They are connected to FPGA, so I can clone any signal. Just tell me what you need and it will be there :D

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Timbucus
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Re: Pi configuration

Postby Timbucus » Wed May 31, 2017 6:01 pm

Thanks Victor - when I discussed this with Andrew Gregson sometime ago on how we could use the PI he has done something similar quote: "On Spectrum I really do hack it - basically reset the Z80, assert ROMCS then feed the Z80 a stream of opcodes to write to memory - basically a sequence of LD A,n LD (nn). PI calculates n and nn to load a code or data into memory and Z80 deals with generating the addresses for memory writes. At end it just executes JP to address where code was loaded. No need for an EPROM. PI can respond to IO and Memory requests from Z80 and if a delay is needed just assert HALT." - So rather than just passively looking at memory we could insert data into memory (you may have a better way already) - the NMI would allow a ROM routine to be inserted to allow the PI to recover crashed code for debugging (either onboard or remote) for example... I am really interested in getting the PI to be a useful dev tool so that I can work only on the machine itself without the need for a PC! the HALT would also allow a PI running a full Linux to still communicate with the Spectrum by creating a small portion of contented RAM in case of delayed IRQ responses etc. I suppose that raises the need for the Z80 to raise an interrupt on the PI when it wants something...
I'm Infinite Imaginations when not in work... PAWS for thought.

cowboycoder
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Joined: Tue May 30, 2017 8:12 pm

Re: Pi configuration

Postby cowboycoder » Fri Jun 02, 2017 7:37 am

I'm also interested in configuring the Pi as an 'on board' host dev platform, so NMI and HALT would be essential/useful in order to do debugging.


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