[Will] wrote a 128MHz Z80-based retro microcomputer which runs on a Papilio Pro board. For those who don’t know, the latter is built around a Spartan-6 LX9 FPGA so you may imagine that much work was required to implement all the computer features in VHDL. The T80 CPU core was taken from opencores, the SDRAM controller was imported from Mike Field’s work but [Will] implemented several additional functions on his own:
– a 4KB paged Memory Management Unit to translate the 16-bit (64KB) logical address space into a 26-bit (64MB) physical address space.
– a 16KB direct mapped cache to hide the SDRAM latency, using the FPGA internal block RAM
– a UART interface for external communications
He also ported CP/M-2.2, MP/M-II and UZI (a UNIX system) to the computer. His project is completely open-source and all the source code can be downloaded at the end of [Will]’s write up.
Thanks [hamster] for the tip.
This is 6,144 RGB LEDs being controlled by a BeagleBone Black and a FPGA. This gives the display 12 bit color and a refresh rate of 200 Hz. [Glen]’s 6 panel LED wall uses the BeagleBone Black to generate the image, and the LogiBone FPGA board for high speed IO.
[Glen] started off with a single 32 x 32 RGB LED panel, and wrote a detailed tutorial on how that build works. The LED panels used for this project have built in drivers, but they cannot do PWM. To control color, the entire panel must be updated at high speed.
The BeagleBone’s IO isn’t fast enough for this, so a Xilinx Spartan 6 LX9 FPGA takes care of the high speed signaling. The image is loaded into the FPGA’s Block RAM by the BeagleBone, and the FPGA takes care of the rest. The LogiBone maps the FPGA’s address space into the CPU’s address space, which allows for high speed transfers.
If you want to drive this many LEDs, you’ll need to look beyond the Arduino. [Glen]’s work provides a great starting point, and all of the source is available on Github.
[Thanks to Jonathan for the tip]
A necessary tool for embedded development is a device that can talk common protocols such as UART, SPI, and I2C. The XC6BP is an open source device that can work with a variety of protocols.
As the name suggests, the XC6BP is a clone of the Bus Pirate, but based on a Xilinx Spartan-6 FPGA. The AltOR32 soft CPU is loaded on the FPGA. This is a fully functional processor based on the OpenRISC architecture. While the FPGA is more expensive than a microcontroller, it can be fully reprogrammed. It’s also possible to build hardware on the FPGA to perform a variety of tasks.
A simple USB stack runs on the soft CPU, creating a virtual COM port. Combined with the USB transceiver, this provides communication with a host PC. The device is even compatible with the Bus Pirate case and probe connector. While it won’t replace the Bus Pirate as a low-cost tool, it is neat to see someone using an open source core to build a useful, open hardware device.
[technolomaniac] is kicking butt over at Hackaday Projects. He’s creating a low cost Arduino based FPGA shield. We’ve seen this pairing before, but never with a bill of materials in the $25 to $30 range. [technolomaniac’s] FPGA of choice is a Xilinx Spartan 6. He’s also including SDRAM, as well as an SPI Flash for configuration. Even though the Spartan 6 LX9 is a relatively small FPGA, it can pack enough punch that the Arduino almost becomes a peripheral. The main interconnect between the two will be the Arduino’s ability to program the Spartan via SPI. Thanks to the shared I/O pins though, the sky is the limit for parallel workflow.
[technolomaniac] spent quite a bit of time on his decoupling schematic. Even on a relatively small FPGA power decoupling is a big issue, especially when high speed signals come into play. Thankfully Xilinx provides guides for this task. We have to mention the two excellent videos [technolomaniac] created to explain his design. Documenting a project doesn’t have to be hours of endless writing. Sometimes it’s just easier to run a screen capture utility and click record. As of this writing, the schematic has just been overhauled, and [technolomaniac] is looking for feedback before he enters the all important layout stage. The design is up on his github repository in Altium format. Due to its high cost, Altium isn’t our first pick for Open Hardware designs. There are free viewers available, but [technolomaniac] makes it simple by putting up his schematic in PDF format (PDF link). Why not head over to projects and help him out?
Continue reading “A Low Cost Arduino FPGA Shield”
Cheap FPGA boards are readily available, as are VHDL implementations of classic CPUs like the 6502, 6809, and Z80. Up until now, we haven’t seen anyone take these two parts and combine them into a complete system that turns an FPGA board into a complete 8-bit retrocomputer. Thanks to [Grant]’s work, it’s now possible to do just that (server on fire, here’s a google cache) with a $30 FPGA board and a handful of parts.
In its full configuration, the Multicomp, as [Grant] calls his project, includes either a 6502, 6809, Z80, or (in the future) a 6800 CPU. Video options include either monochrome RCA, RGB VGA, or RGB via SCART. This, along an SD card interface, a PS2 keyboard, and the ability to connect an external 128kB RAM chip (64k available) means it’s a piece of cake to build a proper and complete portable retrocomputer.
What’s extremely interesting about [Grant]’s project is the fact the data and address lines are fully exposed on the FPGA board. This means it’s possible to add whatever circuit you’d like to whatever retrocomputer you can imagine; if you want a few NES gamepads, an IDE interface, or you’d like to design your own primitive video card, it’s just a matter of designing a circuit and writing some assembly.
If you’d like to build your own, search “EP2C5T144C8N” on the usual sites, grab a few resistors and connectors, and take a look at [Grant]’s documentation and upcoming examples.
Via 6502.org forums
[Valentin] recently tipped us about an FPGA development board he just finished. It is called the FleaFPGA and is aimed to get people interested in the world of Field Programmable Gate Arrays. One of the other reasons that also got [Valentin] to design his own board was that he was frustrated with the existing solutions, them being either too pricey or fairly spare in terms of connectivity.
The main components that you can see in the platform shown above are: a lattice MachX02-7000HE FPGA (6864LUTs), 256Mbits of SDRAM, a USB2.0 host port, a 4096-color VGA connector, a 3.5mm stereo connector, an SD/MMC card slot, a PS/2 keyboard/mouse combo port, a few push buttons and LEDs. An expansion header is also present in order to connect the FleaFPGA to future shields that will be developed. Unfortunately only the board schematics have been released and [Valentin] is currently aiming for a price of $60 per board for <100 quantities. You’ll be able to see a video of the board in action after the break, in which the FPGA has been loaded with a 68000 software core running a variation of the Amiga Juggler Demo.
Continue reading “Introducing the FleaFPGA Experimenter’s Board”
For Christmas, [Hamster]’s wife gave him a mini-oven. Later that day, he tore it apart and built this FPGA controlled reflow oven.
We’ve seen plenty of reflow oven builds in the past. Most of those projects use a microcontroller to do closed loop control, sensing the temperature and toggling the heating element to hit a set point. This build uses the Papilo One FPGA development board as a controller. It implements a state machine that meets the reflow profile of the solder paste, ensuring SMD components are soldered properly.
The oven uses a MAX31855 to read temperature from a thermocouple. This device provides amplification, cold junction compensation, and analog to digital conversion which spits out the temperature over SPI. To control the heater, a 40A solid state relay is used.
The VHDL code that drives this oven is linked in the writeup, and has some interesting bits for those looking to experiment with FPGAs. It includes an SPI interface, display driver, and the temperature state machine logic.