This document is meant to summarize the CC1120 User Guide and provide an easy-to-understand explanation of how the CC1120 Driver works.
CC1120 Driver Features Checklist
The state diagram of the CC1120, found on page 6 of the data sheet, describes the systematic workflow for transiting between IDLE, SLEEP, TX, RX states along with how to handle ERROR states. The state diagram has been copied below.
Below is a list of all the possible transitions between states and instructions on how to perform each. The default state when the chip is powered on is IDLE. You’ll want to read over the sections below before coming to this section.
To control a CC1120, you have to manipulate internal registers (pieces of memory within the device that store some information about its state and properties) over a SPI bus. Note that the datasheet calls MISO “SO”, and MOSI “SI” for short.
Communication begins when the chip select line (denoted by CSn in the datasheet) is pulled low by the MCU.
The MCU must then send a header byte to the CC1120 indicating what register it would like to access, whether this is a read/write operation, etc.
When CSn is pulled high, communication is ceased.