22 Sep
2023
22 Sep
'23
8:42 p.m.
Mike
The level you are working at, inspecting busses, is not really where C like tools are
targeted - however ...
I shall infer that an 8/E debug board has the functionality of a bus monitor / logic
analyser front end.
The recent discussion <<Logic Analyzers - HP/Agilent 16700B or 1670G?>>
covered a lot of similar ground : worth reviewing.
Also, the debug tools for 11's on http://retrocmp.com/
https://digilent.com/shop/cora-z7-zynq-7000-single-core-for-arm-fpga-soc-de…
provides ~79 IOs on an Arduino footprint ('orrible) - quick cheap suggestion for a
candidate hardware platform.
That means you are using the AMD (Xilinx) toochain:
- Vivado as the HDL IDE : VHDL & Verilog, a flakey simulator, HLS (High Level
Synthesis) [c like] tools and IP generation capabilities.
-- inside Vivado a block diagram editor which with a bit of pro forma IP generation might
build your logic without any HDL
-- also inside the IP library / Vivado logic analyser capabilities (ILAs) for capturing /
displaying bus signals
-- and HLS implements SystemC or somesuch : a toolset for C to parallel hardware
development
- Vitis, which is basically Eclipse, for programming the hard Arm core(s)
If you wish an HDL simulator, download Microchip's FPGA development tools - you get
ModelSim.
This will be quite sufficient for pre-synthesis bebug, if you have to simulate post
synthesis revisit the design fundamentals.
There was discussion further up the chain of voltage translation / clipping.
Another cheap and nasty way of doing it is Zenner diodes - works well on perf board.
Todays (fairly) Gucci voltage clamp is an N-FET with a suitable gate voltage; there were
"octal" devices using this teknik.
Voltage translation devices remain quite common, but anything more assembly friendly than
SOIC less common.
However,74LVT is both 3v3 powered, possessed of 5V tollerant inputs and (maybe just still)
in DIL packages, e.g. 74LVT244
Another handy family is 74LVC1G (and 2G ...) which also accepts 5V inputs when running on
3v3 rails, e.g. 74LVC1G17
If you require HiZ, specific thresholds or hysteresis, comparators are your friend, e.g.
TLV3501AIDBV (SOT-23)
Best Wishes
Martin
-----Original Message-----
From: Mike Katz via cctalk [mailto:cctalk@classiccmp.org]
Sent: 22 September 2023 17:05
To: General Discussion: On-Topic and Off-Topic Posts <cctalk(a)classiccmp.org>
Cc: Mike Katz <bitwiz(a)12bitsbest.com>
Subject: [cctalk] Good C to FPGA/PLA compiler
I'm working on the design for an Omnibus (PDP-8/E) debug board and I am not very good
at circuit design. I know there are programs that will compile something that looks like
C into Verilog/VHDL/Abel/Etc for use on some kind of large (more than 64 pins)
programmable logic device.
Can any of you recommend a good C like tool for programmable logic?
Thank you,
Mike