One Propeller to rule them all!
Working at Parallax Inc, I see a lot of Propeller boards and accessories, most of which are manufactured by Parallax. And it’s no wonder, with the popularity of this multi-core 32-bit microcontroller that so many people are starting to realize their product and project goals. But even with all the many boards and platforms for experimenting with the Propeller, this ever growing community is seeing an equal growth in hobbyist development platforms designed by customers.
One such board, the Propeller Platform USB (Figure 1) is a compact development module that has a familiar look and feel to another popular development board; The Arduino Uno. Unlike its predecessor, the Propeller Platform (Figure 2) which used through-hole parts and came as a kit, this next generation module is mostly SMD components and therefore comes completely assembled. This is not typical of kits from Gadget Gangster, however as an engineer I can appreciate the obvious potential for issues selling a kit with so many SMD components. Many people still aren’t comfortable soldering a lot of SMD components onto a board.
This board has options when it comes to both connections and accessories. For connections there is a set of SIP sockets on both sides which provides access to all I/O and power connections. For breadboarding this makes it easy to connect a wire from a point on the module to a point on the breadboard using standard connecting wires. The layout of the board seems well thought out and clean. The reset button is in an accessible location and there are an extra set of pads for every I/O and power pin.
For those who wish a more permanent connection you can also solder your connections directly into the available secondary pads. The module includes both a standard 2.1mm barrel jack as well as a terminal block for connecting power, making it easy to power from a standard wall-wart or wire into your internal power grid.
Having the SD card reader and 64KB EEPROM on board not only provide a lot of storage but open up possibilities for bootstrap loading code from the SD card, which could contain dozens of programs. The SD card interface could also be used for datalogging or for multimedia data storage such as music, sound and video.
While everything mentioned makes the board an excellent addition to anyone’s microcontroller arsenal, the real power lies in the accessory I received with the package. Nick sent me a ProtoPlus board, which is a kit that, when built looks like a shield for the aforementioned Arduino. The ProtoPlus connects to the SIP sockets on the Propeller Platform USB via SIP headers and includes sockets to allow another board to stack on it, hence the shield reference.
The ProtoPlus board also includes four resistors and two RCA jacks allowing you to easily get audio and video from the Propeller chip. Because of the Propeller chip’s innate ability to produce audio and video without additional hardware (except a few resistors), many Propeller chip programmers use the video for debugging or even displaying the output for their project.
This biggest benefit of a socketed protoboard is the ability to swap projects on the same Propeller Platform. Unlike a traditional Propeller Protoboard, when your project is done and you want to do something else you don’t need to buy the entire system again. Instead you can just buy a new ProtoPlus kit ($13.95 at the time of this review) and put a whole new project on the same Propeller-based platform. That should draw experimenters as well as hobbyists due to the cost reduction when building projects. For under $15.00 you can build a whole new project on the same board. And the reverse is true as well; if you damage the Propeller somehow, you don’t have to rebuild your whole project. Just plug it into a new Propeller Platform USB ($49.95 at the time of this review).
The Propeller Platform USB is a very nice development platform for the Propeller chip. The companion accessories (there were several on the Gadget Gangster website at the time of this article) make the board a cost-effective way to experiment and develop many Propeller-based designs. The following items are not intended to reflect negatively on the design, however they are things I would have done differently had I designed the board. Queue internal engineer:
- The unit I received (Rev. C) did not have plated mounting holes. I prefer plated holes for the mounting holes because often screws damage PCB material on development boards, usually from frequent removal and replacement.
- Since the mounting holes were not plated, they provide no easy chassis ground connection when mounting. I especially appreciate this in development boards due to human factor of touching the board more when it is used for development. I prefer to leave isolation in the standoffs or mounting hardware, if required.
- The power indicator is marked VIN, which led me to believe it would be on whenever VIN was present, however this LED does not come on until the power switch is in the ON position. Since the LED is on the switched side, I would have labeled it Power, rather than VIN.
- I would like to see LEDs for both 5V and 3.3V power indication. If these were included, you could leave the VIN LED on whenever power was applied, providing a pad on the board for cutting this LED when used in a battery powered project, if need be.
- The USB interface doesn’t have any LEDs to indicate link status or TX/RX. A link indication at minimum would help with troubleshooting issues when connecting to a PC.
Be sure when you visit the Gadget Gangster site to look around. I did not realize how much stuff Nick has on his site until I started viewing the many pages of projects. And finally, buying from Gadget Gangster helps not only Nick, but the individuals who design these boards. So buying from Gadget Gangster supports the developers of the products Nick sells. This encourages and promotes future development and products from developers who might not otherwise have a venue for their low-volume products.