For the Eagle workshop/2nd PCB group order, I put together a pair of minimal breakout boards for the Parallax Propeller
and would like to make the Eagle/Gerber files available for anyone who might find them useful.
For those who are unfamiliar with the Propeller, it's a 32-bit microprocessor with 8 independent cores called "cogs" that each have 512 32-bit words of memory and run independently. It runs on 3.3V, can be clocked up to 80Mhz, is available in 40-PDIP, LQFP-44, and QFN-44 packages, and costs only $7.99 each.
In addition to the Propeller assembly language, it also runs a higher-level bytecode called "Spin". An online version of the Propeller manual is available here
The following diagram shows the internal structure of the propeller chip:
I basically just took the minimal Propeller schematic at the beginning of the manual and laid that out in Eagle for both the P8X32A-D40 (40-PDIP) and P8X32A-Q44 (LQFP-44) versions of the chip. I've successfully assembled them and programmed each board from Linux without errors.
The boards contain the minimal necessities to get the Propeller running and expose the 32 GPIO pins, a 4-pin programming header, a 4-pin i2c header, and a 2-pin 3.3V/GND header. The chip has an internal oscillator that can run up to 20Mhz, but an external 5Mhz oscillator can be used to clock it up to 80Mhz.
A Parallax Prop Plug
will be needed to program the chip and can be used with more than one board.
Additionally, the Propeller itself does not have onboard non-volatile storage, so it will be necessary to reprogram the chip every time power is removed unless an eeprom is connected to the i2c header.
The supported development tools for the Propeller are currently Windows-only, but it's possible to write assembly language programs using a third-party propasm
assembler and program the chip from Linux using a python script available here
Parallax has released a command-line version of their Spin compiler called Propellent that can apparently be run under Wine and build Spin bytecode files on Linux. More information about that is available here
. I've run the Propellent tool, but haven't written anything in Spin yet.
For the next group order, I'll be submitting modified versions of these boards with thicker traces and an onboard i2c eeprom so that they can be used on a standalone basis without the need to reprogram the chip every time power is removed. If I'm feeling adventurous, I might make a version with a mini-usb connector, ft232r, and the rest of the necessary circuitry to support onboard programming instead of requiring an external Prop Plug, but I dunno if that'll happen yet.
In the mean time, I hope these are useful to someone and help spur interest in the Propeller platform.