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STEbus FPGA universal board [message #8388]

Sat, 20 March 2021 11:14

beb
Messages: 10
Registered: October 2019

Junior Member

Hello all,

as I said in my previous post, I am working on creating some new boards with STEbus interface. I have designed a Universal FPGA Board for STEbus (it can be used as a STEbus Default Master or as a slave, depending on jumpers positions)

The board is based on a Terasic DE0 Nano FPGA board, which is a quite powerful FPGA board (it is equipped with a Cyclone IV with 22000 LE, 32MB SDRAM, plenty of I/Os, 8 channels ADC, 2KB EEPROM, configuration Flash, integrated USB Blaster, etc.. Wink

. This board is not cheap (around $80) but the capabilities are really worth it. To have an idea, a 22K LE FPGA is able to run the equivalent of a Amiga (including video chips)

The board supports the full addressing range of STEbus (20 bits), it supports up to 2 interrupts (selected amongst the 8 possible ones) and can act as a Default Master or as a slave on the STEbus. It provides access to 47 I/O lines of the FPGA for the application.

These I/O lines can be attached to a local host, making the FPGA act as a coprocessor for the host. On the pictures, you can see a KissBox CPU V4 OEM board (the KB CPU V4 has a powerful 32-bit dual core processor, each physical core running at 500MHz, giving an impressive computing power of more than 1000 MIPS). This board also provides 100Base-TX connectivity.

Note that the host processor is purely optional, the FPGA can run fully autonomously (it only depends on the code loaded in the FPGA)

The hardware has been validated so I switch now to the FPGA programming. I am currently debugging a VHDL entity I wrote to drive the STEbus. This entity can be used by softcore processors running in the FPGA (like a Z80 or a 6809), but also under of the host processor.

I will publish all documents and FPGA source code as soon as possible on this forum and on the Wiki (right now, it is still a big prototype, not yet able to run a full applications)

And if somebody else wants to jump in the boat, I have some PCB remaining (of course, I will share the technical documents to those who want to give a try to the board, but don't forget : this is still a prototype) Very Happy