Parallax P2 Edge Module - User Guide

4. Crystal

The P2 Edge Module is equipped with a 20 MHz crystal. Operational frequency is adjustable; for

full operating frequency configuration details, options, and limits, refer to the Propeller 2

documentation at www.parallax.com.

The Propeller 2's on-chip crystal oscillator with internal 9 pF load capacitance drives the 20 MHz

crystal to provide a base clock frequency for the Propeller 2. The actual operating frequency is

selected in code, and can be almost any value or fractional value by using three special multiply

and divide registers.

Overclocking

The clock frequency of Propeller 2 is defined by user code. It can be adjusted very precisely

using three multiply and divide registers that set the actual operating frequency based on a

function of the crystal oscillator frequency. The nominal maximum is 180 MHz, though many

early users have been running the Propeller 2 overclocked at 320 MHz. Advice about

overclocking can be found at https://forums.parallax.com.

5. Flash Memory

The flash memory can be used to store user code or data, and is selectable as the prefered Boot

device, See the Boot Mode Selection section for the necessary switch settings.

The device uses SPI protocol, with 16 MB (128 Mbit) capacity. Refer to the W25Q128JVSIM

manufacturer datasheet for full details.

6. Mode Selection Switch Bank

This bank of dip switches controls the LED power and Boot Mode Selection functions. The dip

switches are not set to any particular state on a new Edge module, although the four switches

will all usually be set to the OFF position.

LED Power Control (On board LEDs enable)

This switch controls power to two onboard LEDs, labelled and connected to I/Os P56 and P57.

Switch ON to enable the LEDs. Switch OFF to disable the LEDs.

Boot Mode Selection

Upon startup or after reset, the Propeller 2 will always proceed according to the boot mode

selection table shown below. The three switches labelled Flash, △ and ▽ are used to select the

Boot Mode, and the options include booting (loading code) from USB-Serial, SD card or SPI

Flash memory.