Sunday, January 4, 2015

Si570 Prototype Board

Si570 from Silicon Labs is a nice oscillator in terms of stability and frequency range.

I got 2 Si570s(CMOS Version 10 MHz to 160 MHz) for my project and I decided to make a prototype oscillator for my experiments.

Since Si570 operates in 3.3V (again for CMOS only) I had to find a level shifter for the SDA and SCL lines. With out the I2C level shifter I will not be able to drive the Si570 from an Arduino Mega.

I have used this level shifter with slight modifications :)

2N7000 is used in place of BSS138, and 4.7K is used instead of 10K.

 LM1117 is used for the 3.3 V regulated supply.

Si570 is not directly soldered, It is hanging in the air :)

As you can see the two output connectors are connected to the CLK+ and CLK- pins of the Si570. Later I realized that the CLK- output is not used in the CMOS version, so I connected the SMA connector to CLK+.

For initial testing the Prototype board is connected to a 5V supply and the Racal Frequency counter indicates 56.3 MHz (based on the factory programmed register values).

Now it is time to write some code to control the Si570.

I need to test the following scenarios

1) Arduino Mega + Si570 + Optical Encoder + KO7M's Si570 library
2) NXP mBed + Si570 + Optical Encoder +  mBed Si570 Library
3) Stm32F429 Discovery + .Net MicroFramework + Si570 + Si570 .net Library ( I have ported K07M 's lib to C#)

I hope I will be able to post the test results soon....