Silicon Laboratories Stepper Machine User Manual download pdf (Page 18)

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5. Enhancements

The following descriptions provide ideas for modifying or expanding the programming technique described above.

 Customizing the Si5338

The Si5338 has non-volatile memory (NVM), which can customize the start-up of the Si5338. Adding an MCU to

program the custom Si5338 after it boots provides access to other features in the device, such as spread

spectrum or frequency adjust on the output clocks. In addition, fewer registers will have to be programmed,

which uses less memory in the MCU. Contact Silicon Laboratories for more information on custom Si5338s.

 MCU-Controlled Power Supplies

The MCU in this application can control a power supply circuit to power the timing device's VDD. The MCU can

send commands over the serial bus to turn on the power supplies after the MCU boots.

 Multiple Plans

Depending on the MCU chosen, there may be extra digital I/O signals available on the MCU. These signals can

be defined to select different register maps to load into the target device at power-up.

 Multiple Slave Devices

The MCU can be used to send individual register maps to multiple slave (timing) devices using the same serial

bus (I

C or SPI). In the case of I

C, the correct I

C slave address must be used when addressing the slave

device and correspond in the firmware with the desired register map. For SPI's slave select (SS) line, the extra

digital I/O pins on the MCU can be used, or an external MUX can be added, depending on the number of slave

devices.

6. Conclusion

The JumpStart model allows system designers to reconfigure Silicon Labs' timing devices as needed during

hardware development without sacrificing manufacturability. The example given in this document demonstrates the

ease with which configurations can be made and changed.

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Silicon Laboratories Stepper Machine User Manual Page 18