VX-Propeller

A configurable system clock supplies all the cogs with the same clock signal (up to 80 MHz). Figure 1-1 shows how each cog takes turns at the option for exclusive read/ write access of the Propeller chip�s main memory via the Hub. Exclusive read/write access is important because it means that two cogs cannot try to modify the same item in memory at the same instance. It also prevents one cog from reading a particular address in memory at the same time another cog is writing to it. So, exclusive access ensures that there are never any memory access conflicts that could corrupt data.

  Propeller specification

• Power Requirements 3.3Vdc (Max current draw must be limited to 300 mA).

• External Clock Speed DC to 80 MHz (4 MHz to 8 MHz with Clock PLL running)

• System Clock Speed DC to 80 MHz

• Internal RC Oscillator 12 MHz or 20 kHz (approximate; may range from 8 MHz � 20 MHz, or 13 kHz � 33 kHz, respectively)

• Main RAM/ROM 64 K bytes; 32 KB RAM + 32 KB ROM

• Cog RAM 512 x 32 bits each

• RAM/ROM Organization Long (32-bit), Word (16-bit), or Byte (8-bit) addressable

• 32 I/O pins. CMOS signals with VDD/2 input threshold.

• Current Source/Sink 40mA per I/O

• Current Draw @ 3.3Vdc. 500 μA per MIPS (MIPS = Frequency in MHz / 4 * Number of Active Cogs)