A help circuit for camera triggering with Micro controller: Two Step Trigger TST01 - page 2

Manfred Fuchs, Germany       FEB. 3, 2001

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Circuit board Template
(click of more detail) Building of the TST01:
If you have ever build an electronic circuit, the building of the TST01 will not be a problem for you. If not, maybe a friend can help you.
First you must make a layout foil. You can print out the layout and reduce it in the right size (see Circuit Board Template) with a copy machine. Now you have a little sharp layout foil. With this foil you have to expose the circuit board. After that, the circuit board must be developed and etched.

The finished circuit board must be drilled (0.8 mm) and filed to the right measurement. After the mechanical work is done you have to add the components to the circuit board and solder them. Don't forget the small wire jumper. Attention: The two 33pF condensers must be soldered in place first, because they are mounted under the IC-socket.
The micro controller should be plugged in an IC-socket. The PIC16F84 is built in a 18 pin DIP-case. 18 pin IC-sockets are not easy to get, so I have used a 20 pin socket. Make sure you have the Micro controller Chip inserted into the socket in the Correct position: It must be plugged to the left end of the socket. The two pins on the right side of the socket are not used.

Mounting plan of the TST01.
(click of more detail) Circuit board of the TST01.
You can print out this layout, reduce it in the right size with a copy machine (40 mm) and use it to expose the circuit board. The layout is mirrored so that the layer side comes to the top of the circuit board. This reduces an under light at the exposing and the finished circuit board is very sharp.

You have to look at the position of the 18 pin micro controllers in the 20 pin IC-socket. It must be plugged to the left end of the socket. The two pins on the right site of the socket are not used. Don't forget the wire jumper. There are no plugs for the servo and the receiver. You must solder some wires to connect the servo and the receiver because the different remote control systems have different connectors.

Editor-breakaway headers (Radio Shack RSU 11323813) could be used to connect most servos. Break off a group of three for input and a group of three for the output. The template would have to be reworked to accommodate the extra space that the headers would take up on the board and to accommodate the new positions for the +/- and signal.

Programming:
If you are interested in the programming code email me atKAPMan@freenet.de and I will send you a copy of the code.
[Ed- the comments within the program are a mix of English and German but this will not effect the operation of the TST01]

The biggest problem will be the programming of the micro controller. There are different solutions:

1. If you have a friend, who has the needed software and a pic-programmer you only have to assemble the source code and program it into the controller chip.
2. On the Internet there are many plans to build a pic-programmer for the PIC 16F84. These easy devices often can only program one type of PICīs, but they are very low in price and easy to build. Do a Google search for "pic programer".
You can get the Assembler to translate the source code at the MicrochipHomepage.
3. If you are interested on programming the PIC-controllers you can get the Microchip starter set. There is everything you need to develop a program and "burn" it into a micro controller. There is a editor, a assembler, a very good debugger and of course the programmer hard- and software. With this starter kit you can program many different types of PIC-controllers. The two CD-ROMīs are filled with software, data sheets, examples and so on.

Test and adjust the TST01:
The circuit is designed for use with 4.8V.
If the circuit is built, the controller chip is programmed and plugged into its socket the circuit can be tested.

If you have a power supply you can do the first test with this and look at the current of the device. The two LEDs are flashing for a short time to say that the circuit is going to work. It is the "ready signal". If there is no servo the current will be approximatly 3 mA without any LED and approximately 20 mA if both LEDs are on. If this first test is good you can test and calibrate the TST01 at your receiver with Rig and camera.

For the first time all DIP-switches are set to 0. Switch on the power and the two LEDs flicker for a short time, the "ready signal".

If you move the control stick on your transmitter now, the two LEDs show the two functions MEASURING (LED 1) and TRIGGER (LED 1 and LED 2). A plugged servo moves only a little bit in two steps.

Now you can adjust the servo movement for the MEASURING POSITION with the switches S3 to S5. Switch them into that position, so that the camera does the measuring but not the triggering.

After that you have to adjust the measuring time with S1 and S2 to the need of your camera. You can choose times from 2 sec. up to 3.5 sec. in four steps.

At least switch the DIP-switches S6 to S8 to adjust the servo in the pos TRIGGER.

You have to look for the significance of the switches. For example see the table above. It shows the switching for the measuring time with S1 and S2. (0 = open, 1 = closed):
The switching of S3 to S5 for the MEASURING POSITION of the servo and S6 to S8 for the TRIGGER POSITION is equal but you have eight different possibilities or servo positions.

Possible developments for the future:
You can leave [out] the DIP-Switch and program the TST01 with a programming-switch and a programming-led. The programmed positions and timings can be stored in the EEPROM of the PIC - controller. Then the device can be much smaller and all times which are not programmable in this version (TST01) can be adjusted.
Future??


Enjoy building the TST01 and of course enjoy KAPing with the Two Step Trigger.
If you have any question, write an e-mail. But think: I am German, write in easy words, so that I don't have to look in the dictionary for every word. :-)

Editor- You can find this same article written in German on Manfred Fuchs' web site http://www.kap-man.de/tst01.htm

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