Bringing up a new board

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Part 2: Hello World

Since my last post I’ve received yet another board from Emanuel – another prototype FPGA board with Spartan 6, SDRAM and SSRAM.  This one’s a little simpler than the previous board, with no ports other than USB on the board itself, and a daughter card with a VGA connector on it.  Unlike the previous board, which had a 2-bits-per-gun resistor ladder DAC, this one has an ADV7123 video DAC chip – the same one used on the DE2 board – which has an impressive 10 bits per gun.  That’s good enough to do 24-bit true colour with headroom for calibration tables!

EMS11-BB21

So, let’s get “Hello World” running on this board. Continue reading →

Bringing up a new board

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Part 1: The Plan!

Having received the ESM-BB10 Spartan 6 board a couple of weeks ago I was naturally keen to see it in action.  Since I only have the free “WebPack” version of Xilinx’s ISE design suite, I can’t use the ChipScope logic analyzer (roughly equivalent to SignalTap, I believe) – so debugging is going to be tricky.  Therefore I’ve taken a methodical, step-by-step approach, testing the various parts of the board one by one.

The ZPUDemos collection is ideal for this purpose, since the projects there range in complexity from a simple “Hello World” that requires no peripherals apart from RS232 serial, to projects that make use of VGA, SDRAM and SD card. Continue reading →

No, I haven’t vanished!

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Apologies for the lack of recent updates.  I haven’t been completely idle but my time’s being filled with other things at the moment, including replacing light fittings, hanging pictures and learning the guitar!

Despite the silence, I’ve not been completely inactive on the FPGA front, however, and I’m still slowly building my library of demo projects for my “Flex” variant of the ZPU processor.  In the process I’m redesigning and streamlining a lot of the components that made up the TG68MiniSOC project, so that will be updated with the results before too much longer, and I’ve also started branching out from being purely Altera-based into Xilinx too.

This last development is the result of reader Emanuel Stiebler very generously supplying me with a Spartan-6 board!

ESM-BB10

This has an XC6SLX45 FPGA, 32 megabytes of SDRAM, 4 megabyte of SSRAM, a microcontroller, dual micro-SD slots (one for the µC, one for the FPGA) and an assortment of IO ports.

I’ve already ported a few of the ZPU Demos to this new board (and a couple of the simpler ones to the original Minimig board while I’m at it!) but will post about the process in more detail soon.

A Clockport for the Chameleon64’s Minimig?

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Christian Vogelgsang, who a couple of years ago collected together the git repository of Tobias Gubener’s Minimig_tc64 project and ported the OSD menu code to GCC – thus sparking my interesting and subsequent foray into the world of FPGA development – has been hard at work once again!  This time he’s succeeded in adding support for the Chameleon’s clockport to the Minimig core, which means that in theory a good proportion of clockport peripherals should now be usable!

So far it’s only been tested with a Silver Surfer card – it will be most interesting to see which cards work without any further changes, and which prove to be troublesome.

Links to source, binary and details of a small hardware hack required can be found on Chris’s blog – but before downloading and trying them take note that

THIS MUST NOT BE USED WHILE THE CARTRIDGE IS PLUGGED INTO A C64.

The IO mux code has been stripped right down to bare bones to give usable clockport performance, and the synchronization with C64 bus cycles is no longer present, so a connected C64 will definitely crash, and may even be damaged.

With that warning in mind, do check out his work here: http://lallafa.de/blog/2013/09/a-clockport-for-chameleon64s-minimig/

Hello World in 684 logic elements!

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You may have noticed the new “ZPU” section on the header of this site. The ZPU is a very useful little processor, and I think it’s under-appreciated because of a lack of documentation and design examples – so I’m trying to redress the balance a bit with my ZPUDemos repository.

So far I have a very simple Hello World project, which on an Altera DE1 board takes up a tiny 684 logic elements, including RS232 transmission. The ROM is also pretty tiny, bearing in mind it’s written in C, at under 2kb.

The repo also now contains Dhrystone benchmark projects, which use the ZPUFlex variant both with and without the optional hardware instructions, turning in about 1.7 DMIPS for the barebones configuration, and 5.1 DMIPS for the version with optional hardware instructions enabled.

More demos will follow in due course.

The next generation of Retro fans?

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My nieces visited today – and spent a very happy hour playing two of my old favourite games – Pang and Lotus II. Both games went down extremely well with the girls despite being released about 10 years before they were born! While I still find a lot of fun in classic games, it’s encouraging to see that they’re enjoyable even to the iPad generation.

I was rather amused, however, that they were playing such ancient games on brand new, 2013 hardware: For Pang we used Majsta’s prototype Vampire 500 board, while we ran Lotus II on one of Till Harbaum’s prototype MIST boards!

Learn something new every day…

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So while I’m experimenting with FPGA boards I generally upload a design into them at runtime via a USB-Blaster JTAG cable, and only rarely do I store a design permanently in a board’s configuration device.

Some of the boards I use have two separate connectors for the USB Blaster – one for direct programming of the FPGA and the other for Active Serial programming of an EPCS series flash device.  Others have an onboard microcontroller which handle configuration – and then there’s the Vampire 500 board.  This has a single JTAG connector and an EPCS4 configuration device, but no immediately obvious means of programming the EPCS4. Continue reading →

Well that was nerve-wracking!

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My Vampire500 board came with “some assembly required” – the FPGA, SDRAM and level translators were all in place, but installing the non-essential stuff – the micro SD slot and PS/2 socket – was left as an exercise for the user!

I want to press the Micro SD slot into service so that I can load alternative Kickstart ROMs, because my old A500 board has kickstart 1.3, and I need a more up-to-date ROM to test Zorro III autoconfig, and to run certain test software.

As it happens I haven’t done any surface mount work before, so I was a bit nervous about attacking an almost-one-of-a-kind board with a soldering iron – but after butchering the control board from a dead hard-drive and convincing myself that I *am* capable of soldering on that scale, I had a go at mounting the micro SD socket.  I was relieved to find that it has locating pegs that fit holes in the PCB, so at least I didn’t have to worry about alignment.

MicroSD

Well it *looks* OK – now to see if it actually works!