Few facts about CC1000 chip

Description

The CC1000 is a single chip UHF transceiver manufacturing by Chipcon. It works in wide frequency range from 300MHz to 1GHz and offers data rate up to 76.8 kbit/s (in Manchester mode 38.4 kbit/s only). CC1000 is designed for low power applications and (according to datasheet) it will consume 0.2 uA in powerdown mode, ~10mA working as receiver and up to 15mA when transmitting data in normal mode (0 dBm).

First and most important thing about transmitting data with CC1000 is that it just provides digital transmission. Nothing more. With properly set CC1000 chip you can think about ones and zeros, but you can't think about packets. Everything above – checksum like CRC32 or any protocol are not provided. On one hand – it's good, you are totally free to implement (almost) any protocol, but on the other – you have to do everything yourself.

Interfacing

Chipcon sells CC1000 chips in minimodules called CC1000PP (Plug&Play) – small modules with chip and few passive elements onboard, designed for 433 or 868MHz. Difficulties begin when you want to connect CC1000PP to 5V microcontroller. CC1000 is low voltage chip, supply voltage should be 3V. You'll find some tips about voltage level conversion on Chipcon's webpage. They suggest to use 74LV245 buffer or just make this conversion with some transistors. I chose the first way. Indeed I used 74HC245 because I could'nt get LV. It's not a good idea and it should'nt be done with HC but… it works.

Second problem are bidirectional lines in CC1000PP. If you have 5V microcontroller you'll probably can't use one microcontroller pin to control bidirectional pins like PDATA or DIO. You'll have to split those lines. It's quite simple with multiplexer. I used 74HC4052 from Motorola.

Third and last thing is stable 3V supply voltage. I decided to use LP2950. It's a voltage regulator for 3.3V. It's small and I have'nt noticed any heat when it was working.

If you have small board which provides supply, voltage level conversion and divides bidirectional lines you can almost begin transmission… almost.

Configuration

CC1000 is programmed by 3-wire interface. This interface is used for reading or writing 28 registers. First step is to get this interface working. It can be done with "bit bangling" method or SPI interface. First method is simple but, in my opinion, it's quite dirty. You can find this method in Chipcon's example on their website. They provide an application note with library for AVR microcontrollers, nice for beginners.

Second thing is to calibrate CC1000. Chipcon's SmartRF Studio provides registers value. It can be downloaded from their webpage for free. You have to set few options like transmission mode or speed and SmartRF will generate properly values.

Calibration procedures are well described in CC1000 datasheet, examples can by also find in Chipcon's application notes. All procedures are in fact only series of reads, writes and delays.

Transmission

Last step is data transmission. CC1000 offers three modes of transmission – uart, NRZ and Manchester. In last two CC1000 provides the data clock at DCLK pin. It can be used to cause interrupt or it can be polled. If you'll get to this point you'll be able to send and receive bits.

I met some people who told me, that CC1000 is too difficult for them, but there were also some who said it's very easy. As usual – if you know something well – it's easy…