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The best place to ask questions is at the Parallax Forums: https://forums.parallax.com
You can also contact me directly at "martin at 1mgh dot com"

Propeller Platform DNA

The Propeller DNA is a Propeller Platform compatible system that adds USB power, optional RTC circuit and more.

Design Files

Solder Jumpers

Dna-02.pngDna jumpers.png
(Click images to enlarge)
There are five sets of pads on the back of the DNA that are used to select which set of Propeller I/O pins drive the microSD slot and U9 socket. The DNA is shipped with the lower set of jumpers bridged to be compatible with previous versions of the Propeller Platform.

DC Input Requirements

The 2.1mm DC input jack on the DNA requires a voltage between 6.2 and 15 VDC. However, supplying more than about 9 volts will require careful monitoring of the on-board voltage regulators for overheating if you are drawing more than 500mA from the board for external circuitry. The DC input jack and the DC input terminal blocks are tied in parallel and protected from accidental reverse voltage by a 1A diode with a Vf of 1.1. This diode does not protect one DC input from the other, so attention should be paid to polarity when using them as a power pass-through.

The power switch on the left side of the DNA only switches power from the DC inputs to the board. It does not disconnect one DC input from the other, nor does it affect power from the USB port.

U9 & U12

The Winbond flash RAM chip supplied with the RTC enabled version of the DNA can be used in either 8-pin DIP socket, U9 or U12. When this chip is plugged into U9 it operates in standard SPI and shares the DI, DO and CLK lines with the uSD card socket. U9 uses a separate CS line which allows both devices to be used in an "interleaved" fashion.

U12 is a general purpose 8-pin DIP socket that is compatible with many different kinds of devices. When the Flash RAM chip is plugged into this socket, special drivers can be used with PropGCC to operate this chip at a much faster quad speed SPI. (If you are not planning to use PropGCC, the Flash RAM chip might be more useful in U9.)

U9 was intended to be used specifically with the Winbond Flash RAM, but can be used with any 8-pin DIP device that has the same pinout.


The Propeller DNA is supplied with a 64 Kilobyte EEPROM. The first 32 Kilobytes can be used for Spin/PASM applications, with the second 32 Kilobyte bank available for runtime storage of data. The entirety of the EEPROM can be used for GCC or Catalina C compiled programs, (see their documentation for info on this.)


Please read the data sheet for complete information on the Seiko RTC.

Roy Eltham has written a Spin driver for the Seiko RTC. See This Thread in the Parallax forum.

The Seiko Real Time Clock (RTC) circuit provides an accurate clock and calendar readout. It is connected in parallel with the EEPROM using an I2C bus architecture. This bus is driven by propeller I/O pins 28(SCL) and 29(SDA). It uses a 32.768 KHz Crystal with a 10ppm accuracy. A 0.33F supercap supplies power to the chip and watch crystal when the DNA is powered off. A Schottky diode recharges the supercap when power is applied to the DNA. It takes about 5 - 10 minutes to fully charge the supercap from a completely depleted state. The supercap will power the RTC for a approximately 20 days between power cycles.

J11 on the board provides a connection point to the Seiko's two interrupt outputs. The Seiko can be programmed to trigger these outputs at a set time and date. For example, these outputs could be used with a WAITPxx command in the Propeller to trigger some action at a specific time of day. The Seiko can also be programmed to provide an accurate 1PPS signal on the bottom pin of J11. Both of these outputs are open-collector, so you will need a pull-up resistor to 3.3v in your circuit if you plan to utilize them.

Micro-SD slot

The SD card slot on the Propeller DNA is connected to the Propeller chip through a series of solder jumpers (described above) on the back of the board. There is also a socket provided (RP1 on the front) for a 5-pin resistor pack to act as pull-ups for the SD. Normally you will not need this resistor pack, but a small number of Propeller SD card drivers expect there to be pull-ups. A suitable resistor pack is included with your Propeller DNA. To use the resistor pack, simply plug it into the socket (or solder it in place) with the pin 1 marking aligned with the triangle printed on the board.


As of this writing the Propeller GCC project is still in early beta. The information below is subject to significant changes. Please check here often (and the PropGCC forum at Parallax.com) to keep up to date.

To use PropGCC on the Linux command line:

  1. Install PropGCC from the Google Code Repository
  2. Be sure /opt/parallax/propeller-load/ contains "dna.cfg".
  3. Continue on to PropGCC for Linux

To use PropGCC on Windows with SimpleIDE:

  1. Install SimpleIDE which will also install the latest release of PropGCC
  2. Check c:\propgcc\propeller-load for the file "dna.cfg" and copy it to there if necessary.
  3. Continue on to PropGCC for Windows