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OpenTag Radios

OpenTag can be ported to many kinds of radios. In this case, a “radio” is a two-way device (a transceiver) that supports at least RSSI, Preamble+Sync-word-based listening, and some type of binary data modulation. Most radios that OpenTag will ever use support an register-based SoC interface or some type of SPI-style interface.

Basic Requirements

It is possible to write a driver for almost any type of radio, even the most rudimentary devices. However, given the large availability of low-cost, sophisticated silicon radios, these are the expected targets. Below is a list of basic, practical requirements that enable OpenTag to work nicely with the chosen radio platform.

Feature Basic Requirement
Packet Support Preamble + Sync Word + Payload
Data Bufferring Internal FIFO for RX/TX, at least 16 bytes
Data Interface Register-based, with serial databus or direct memory access
IRQ Interface At least 2 IRQ sources to signal radio events (e.g. sync-word detected)
RSSI RSSI reporting with 3dB resolution or better

Practical Requirements

As you may know, OpenTag is designed primarily to work with DASH7 Mode 2, so the best performance will be achieved when assuring that the radio also meets DASH7 Mode 2 requirements.

Feature Practical Requirement
Spectrum Supports 433.05 - 434.79 MHz band
Modulation Supports filtered-FSK (typically GFSK) with +/-50 kHz Fdev
Data Rate Supports 55.55 kbps and 200 kbps
Preamble Configurable length between at 4-8 bytes, and 10101010… data usage
Sync Word Supports 16 bit sync word with PQI or 24 bit sync word without PQI
Normal Packet Mode 256 Byte frame with length byte as byte 0
Multiframe Packet Mode Ability to support packets up to 65536 (theoretically) in length
Interrupt Sources Chip Ready, Carrier Sense, Clear Channel Sense, Sync Word Detected, Buffer Low, Buffer High, Buffer Empty, Packet Done, Error

Radios Currently Supported

Chip Manuf Status Notes
CC110x TI Active Sub 1 GHz radio with full feature support
CC430 TI Active Part of CC430 SoC, full feature support except CRC & FEC
MLX73xxx Melexis Preliminary Sub 1 GHz radio family with full feature support except FEC
SPIRIT1 ST Active Sub 1 GHz radio with full feature support
SX1212 Semtech Active 433 MHz radio with support for low-rate channels (55.55 kbps), and very low power RX
SX1231 Semtech Active Sub 1 GHz radio family with full feature support except CRC & data encoding

Radios That May be Supported in the Future

Here is an inexhaustive list of radios that should be able to work nicely with OpenTag, and thus might be supported in the future. If there are others you know about, please contact JP. Alternatively, join the wiki and add a row (keep in alphabetical order please).

Chip Manuf Status Notes
ADF7023 ADI Active Sub 1 GHz radio, should support most features, uncertain about preamble
ADuCRF101 ADI Active SiP combining ADF7023 and an ARM Cortex M3 MCU
ERF4 Draco Energy Micro Preliminary 433 MHz SoC or radio core component – should support most or all features
SX1282 Semtech Active SoC combining SX1212 radio and a CoolRISC MCU.

RF testing with GNU Radio

GNU Radio provides cost-effective method of testing radio transceiver. See testing_with_gnuradio.

opentag/radios/main.txt · Last modified: 2013/12/07 19:22 by jpnorair