July 31, 2012
For PropBerry, I was thinking using a Parallax Propeller* (or just Prop) as a super i/o co-processor for the RPi where the Prop would be used to offload the real-time I/O and let the RPi handle the higher program features. After talking about this combo on the Parallax forums, the Props VGA video capabilities were mentioned which got me thinking about using the PropBerry as a VGA serial terminal console and shelve the i/o co-processor idea for now.
The Parallax community is great and they’ve released a lot of good stuff. One of the things I remember (from about 2009) was Vincent Briel’s PockeTerm terminal software for the Prop. Using this on a Propeller Demo Board gives us a VGA video output and PS/2 keyboard for user input. A serial interface connects the Propeller demo board to the Raspberry Pi.
Now we got our bits together lets see if we can make them work 🙂
* The Parallax P8X32A Propeller chip (or just Prop) is a cool chip. It is a multi-core architecture parallel microcontroller with eight 32-bit RISC CPU cores (cogs) which share a common hub of 32K-RAM
February 7, 2010
Recently I’ve been working on XArduino which is a XMOS XS1 L1 co-processor for the Arduino open-source electronics prototyping platform.
The XArduino board provides Arduino applications with a 400 MIP’s multi-threaded 32-bit co-processor, as well as providing a VGA video output and PS/2 keyboard/mouse input for Arduino application.
It features a standard XTAG-2 to for programming and debugging. In addition the XTAG-2 interface will allow for XK-1 boards to access the VGA and PS/2 interfaces as well as way of connecting standard Arduino shields.
Note: This is a 3.3V-only board
The project is hosted at xcores.com/projects/xarduino
Creative Commons Attribution-ShareAlike 3.0 License
January 7, 2010
X-DTV is a project I’ve been working on with Yvo of xcores.org. The idea is to make a XS1-L1 64 based retro-minimalist homebrew game console similar in concept to the Uzebox and Zuzebox.
Like the X-One before it, X-DTV will use Yvo’s VDP video engine but instead of driving a VGA output it will drive a NTSC TV output. We hope to get PAL TV as well but the 35.46895MHz oscillators have proven difficult to get a hold off (If anyone know where we can get them off the shelve without a large MOQ then drop me a comment).
The X-DTV’s specification is:
- XS1-L1 64 internally clocked to 400MHz with 64K RAM.
- 5-bit R-2R Video DAC for driving NTSC
- 2x NES or SNES D-PAD connectors
- SD Card interface
- Stereo PWM audio
- XTAG-2 Interface
- 2x 5-way XLINK for expansion
The latest (not quite complete) PCB is below:
A PDF of the schematic is here.
November 24, 2009
I’ve talked a few times about the X-One Xmos based console so I thought better put up a schematic to show how it all goes together. A Xmos XC-2 is found at the heart of the console with the rest of the circuit providing a R-2R video DAC, PWM audio and SD Card interface. Ethernet is provided by the XC-2 card its self. The software kernel is Yvo’s VDP video engine.
The pdf is here: XC-2 VGA 0v10
November 7, 2009
Sparkfun have a new Xmos based development board. It features the powerful Xmos XS1-L1, multi-threaded processor. The processor is the XS1-L1-64 processor and is housed in a 64LQFP package and has the following features:
- Event driven processing at 400MIPS
- 64 kBytes of SRAM
- 8 threads
- 36 user I/O pins
- 8 kBytes of OTP
- power consumption typically 450µW/MHz
As well as the Xmos processor the SparkFun development board also features a USB interface based on FTDI FT232, external Flash EEPROM and a JTAG header. I/O is provided by 32 I/O pins brought out to pin headers next to a small prototyping area. Checking out its schematic, it looks like it can be powered form both a wall adapter and its USB port. The USB interface is to support a UART over USB and can’t be used to directly program the processor. Instead a 20-pin JTAG interface is provided. This looks to be compatible with Xmos’s own XK-1 JTAG interface and therefore Xmos new XTAG2. I’m hoping my XC-2 JTAG adapter will work with it as well.
Its competitively price at $50 or ~£30 but you still need to provide a JTAG adapter but these are available for $50. The only criticism I would make is I would liked to see the on board USB used to provide a programming (JTAG) interface as Xmos did with their XC-5 board but that said I’m hoping to get one soon and use it in my X-One console with Yvo’s VDP VGA video driver.
November 3, 2009
As promised in my post of 15th October, here’s some screen shots of Manic Miner on my Xmos XC-2 based X-One console. So far I’ve only coded level 1 and I need to add code for the SNES controllers and game play and off course the rest of the 20 levels to finish it off.
The graphics were hand coded by extracting the pixel data and colour attributes for the first level from a Manic Miner ZX spectrum binary. A very mandraulic process involving switching between two editors and a couple of editor macros but it got the job done. I used Andrew Broads and Icemans (Chris Wild) excellent web sites for the screen layout information. The video engine is Yvo’s VDP for the XC-2 which provides up to 2 backgrounds and up to 32 sprites (8×8, 16×16, 32×32, 64×64 etc)
Watch this space more to come.
October 15, 2009
Its a year to the day that I first heard about Xmos and their cool multi-core multi-threaded processors and joined the Xlinkers community. So I want to share some pictures of a XC-2 project I’ve been working on.
X-One from Front
X-One from above
I’ve used Yvo’s great VDP video driver to get VGA graphics working on the prototype with R-2R resistor DAC for the video and a couple of spare SNES controllers for the gaming inputs.
I’m porting a classic 80’s video game, so watch this space 😉