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projektid:arendusprojektid:minitrxeb

MiniTrxEb

MiniTrxEb

Texas Instruments CC1120 / CC1200 series RF transceivers are really promising in long range communication and it would be great to use them in hobby projects such as robotics, however the initial cost of development kit and suitable transceivers is bit too high for smaller projects. Development kit contains two modules, but most of the times just one is enough because you probably develop one node at time - like your robot or PC terminal - or just sniff the communication. Also with kit you have to pay for MSP430, LCD and other stuff which you probably don't use when developing some other MCU SW.

As TI SmartRF TrxEb development kit schematics are freely available the idea was to build a basic SmartRF compatible kit my own. Kit turned out to work well and I decided to share it with others who might want to build it for them also. The whole kit (USB board and RF board) costs around 100€ if you get cheap PCB's (e.g. from ITead).

Kit is made on the same concept as TI kit by using separate USB carrier board and transceiver board. Carrier board is named MiniTrxEb because it's smaller (5 x 5 cm) than TI TrxEB. Original TrxEb schematics are taken for reference but schematics are done by me from scratch. Transceiver board connectors are physically and electrically compatible with original, meaning that it's possible to use Texas Instruments RF evaluation modules.

All the connectors on carrier board are through hole because they hold stronger than SMD and are way cheaper than shrouded SMD connectors. Basically only component which is same on MiniTrxEb and reference design is the CC2511F32 SoC, the rest is just best-available components. As there's no MSP430 on-board there's no need for extra mode switches and these are replaced by pull down/up resistors. Reset switches and current measuring options remain.

To make the board working you need to download the original TrxEb firmware which comes with SmartRF studio (see Legal). For downloading you need the TI CC Debugger. Read the development kit manual for exact instructions. I didn't make a full BOM with part numbers because I used already existing components.

CC1200 433 MHz module

CC1200 433 MHz module

I needed CC1200 433 MHz transceivers which don't come with original CC1200 development kit so I would have had to buy a pair of these transceivers. Instead I decided to build a one transceiver board on my own because it was cheaper (and just fun trial :-) ). CC1200EM 420-470 MHz reference design was taken as basis on schematics but layout is completely different - it's on 2-layer not 4-layer PCB. As bottom side is almost completely GND plane so it should work quite good. Traces are tried to match to 50 ohm as much as possible. All connectors (including antenna SMA) are through hole again.

There's one little bad thing though - the through-hole antenna SMA connector on self-built RF module goes very close to the carrier board debug pins, although it does not hit them. It's just something to note if you don't want proximity of digital signals. But if it's a problem then it's possible to use two stacks of board connectors. It's not a problem with original TI RF modules because they are smaller.

These schematics are self-made and they are free to use by anybody for academic or hobby purposes. You use the schematics on your own risk. Schematics are done in Altium Designer 14 Academic version.

Software license (SmartRF Studio SLA) coming with SmartRF studio states the following:
The Licensed Materials are for use solely and exclusively with either a TI evaluation board or hardware tool that incorporates or uses a radio frequency device manufactured by or for TI or its affiliates (“TI Device”), or your or a third parties’ hardware products that incorporate or use a TI Device.
So it is allowed to use the SmartRF firmware image on self-made board as it contains the TI chip. But it's not allowed to sell such board with firmware.

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projektid/arendusprojektid/minitrxeb.txt · Viimati muutnud: 2016/09/03 16:25 persoon raivo.riiel