Circuit design for multiple UART connections

[Bill Porter] has a tip for designing circuits that have multiple connections to a single microcontroller UART. This stemmed from a review of a friend’s circuit design that used the UART in the project, but also called for an FTDI chip in order to reprogram via USB and a bootloader. Unlike the schematic above, the circuit called for straight connections without any resistors. With that design, a conflict will occur if two devices are connected and attempting to communicate at the same time.

The fix is easy. [Bill] discusses how to prioritize the connection by adding the pair of current limiting resistors seen above. This helps to ensure that damage will not occur, and that the FTDI chip will take precedence. Now the external hardware will not preclude the FTDI chip from accessing and programming via the bootloader. The tutorial is intended for those rolling their own boards out of an Arduino-based prototype, but it will work in any situation where you need multiple connections to a single set of UART pins.

Gitbrew brings OtherOS back to the PS3


Instead of simply watching the days pass by while the PSN network continues to be unavailable, why not do something useful with your PS3 console? [MS3FGX] wrote in to share some news regarding efforts to bring the OtherOS option back to the PS3.

The team at have been diligently working to bring Linux back to the console for a little while now, and have released a dual-boot firmware they are calling OtherOS++. This firmware has two huge benefits over Sony’s original attempt at Linux support for the console. It can be run on the original “fat” PS3s as well as the newer “slim” models – something that was not possible until now. Additionally, it gives the Linux install full access to the PS3’s hardware rather than running the OS inside a virtual machine.

The project is relatively new, so the installation procedures and associated documentation are not suitable for the less experienced individuals out there, so consider yourself warned.

We love that there are people doing all they can to bring this awesome feature back to the PS3 – it’s a huge step in the right direction.

[Image via gitbrew]

Automated chip burning

[Alexsoulis] needed to burn the Arduino bootloader to a slew of ATmega328 chips. Instead of sitting there and plugged the chips into a programmer one at a time, he build a robotic microcontroller programmer.

It starts with the DIP package microcontrollers in a tube, with a servo motor to dispense them one-by-one. An arm swings over and picks up the chip with a fish pump powered vacuum tweezers similar to the pick-and-place head we saw recently. From there the chip is dropped into a ZIF socket and programmed by an Arduino. Once the process is complete it is moved to the side and the process repeats.

We’ve reported on using an Arduino as an AVR programmer but we’ve never actually done it ourselves (we use an AVR Dragon programmer). Take a look at the video after the break and let us know if you think the actual programming seems incredibly slow.

[Read more...]

Munchausen makes NES a cartridge programmer

What a beautiful image of NES cartridges showing their private parts. These are the raw materials for the Munchausen Flash Cartridge project. A combination of a modified game cartridge and special USB cable makes it possible to program NES cartridges while inside an unmodified console. The cartridge has an added flash chip that is running a bootloader. By connecting a USB-to-NES cable to the second controller port a game image (or custom code image) can be flashed to one of the three game slots on the writable cartridge. The bootloader provides a menu at power-up to select between the three stored images, or can go straight to the previously selected image by holding down A when the console is turned on. There’s even a recovery routine in case of problems. Check out the demo after the break.

One thing we find interesting from the forum thread is a mention that it is technically possible to run code on the NES directly from the PC. That would sure make it easy to perform live chiptunes on NES.

[Read more...]

Minimalist AVR programmer is just fab!

Whether you’re burning a new bootloader to an Arduino board, or doing away with a bootloader to flash Atmel chips directly, an in-system programmer (ISP) is an indispensable tool for working with AVR microcontrollers. If cost has held you back, it’s no longer an excuse: FabISP is a barebones USB-based AVR programmer that can be pieced together for about ten bucks.

FabISP was created by [David Mellis] as a product of MIT’s Fab Lab program, which provides schools with access to design and manufacturing tools based around a core set of fabrication capabilities, so labs around the world can share results. But the FabISP design is simple enough that you don’t need a whole fab lab. It’s a small, single-sided board with no drilling required; the parts are all surface-mounted, but not so fine-pitched as to require reflow soldering. Easy!

There’s still the bootstrap problem, of course: you need an AVR programmer to get the firmware onto the FabISP. This would be an excellent group project for a hackerspace, club or school: if one person can provide the initial programmer to flash several boards, each member could etch and assemble their own, have it programmed, then take these out into the world to help create more. We must repeat!

[Thanks Juan]

Optiboot makes your Arduino faster, sleeker

Tired of waiting for that Arduino sketch to upload? Find yourself limited by code space? Optiboot eases both of these problems. The package is an alternative bootloader that runs at a higher baud rate (115200 versus 57600) and it takes up 1.5 KB less space than the stock version. This means your sketches can be larger without upgrading to a beefier chip and they will take less time to upload, a lot less.

This fully compatible alternative to the Arduino bootloader requires an AVR ISP programmer to burn it to the chip on your Arduino. If you have an extra AVR lying around you could use the Arduino as a programmer and then physically swap the chips.

[Thanks Peter]

Dell Vostro A90 hackintosh


A friend recently commissioned us to install OSX on a netbook. We advised him to purchase the Dell Vostro A90. It’s essentially a rebadged Dell Mini 9, a model that has been discontinued, but is well suited for OSX. It’s only available with a 1.6GHz Atom processor, 1GB RAM, and 16GB SSD. Depending on what deals are available, it’s $250-$300. We also had him purchase a 2GB stick of RAM which is the upper limit supported by the BIOS. [Read more...]