RF trigger

Problem Statement

I want to be able to remotely control my camera. Autofocus, shutter, and an acknowledge signal are important to me. The system should be small, portable, and not use much battery power or large battery packs.

System Overview

Two nearly identical circuits provide a bidirectional 915mhz, 10mW digital RF packet based link in the form of two small 1"x2" boards. One board has buttons and the other board has a stereo jack for interfacing with the camera. The circuits are based on the CC1100 radio chip and use an MSP430F1232 for control. Each board is powered by a single ipod or cell phone battery. Originally intended for remote camera operation (for use with kte areal photography, for example), they have also been used as short range balloon poppers and parachute cutdowns. They can also be used to wirelessly trigger a flash unit, or anything else really.

What they look like

Here are the bare circuit boards. This version was custom made for a friend. The boards are cleaner with epoxied power switches and built-in USB chargers for the lithium polymer batteries.

I have since placed my circuits into protective and decorative cases. The reciever is now a monkey.

How far they go

At the default 10kbaud setting I have gotten over 2,000 ft line of sight. At 1.2kbaud the distance should be signifigantly increased. At 250kbaud the distance will be signifigantly decreased.

They can be easily modified for 70cm band use, though the antennas will be correspondingly larger. The maximum link distance in theory could be extended by a factor of four.

Can I get the circuit from you?

I can assemble small quantities of boards or provide them as kits. The cost is roughly $50 per board (as I do not order parts in bulk quantities) and the entire board would be assembled by hand and tested by me.

MSP430 Source Code

Transmitter code can be found here (For reference only, all rights reserved)

Receiver code can be found here (For reference only, all rights reserved)

2009 Jasper Nance KE7PHI