DC power in the range of 7 to 35VDC is supplied on JP1 and is filtered by C1.  The input voltage is converted to an internal bus voltage by the switching regular IC3.  IC3 operates at 52KHz and its output is filtered by D2, L1, and C2.  The 5VDC output is distributed through out the circuit board.  Bypass capacitors C4, C11, C12, and C16 are placed near each major component.  LED1 provides a visual indication the power supply is active, while R1 limits the current to 15mA.  The heart of the control system is IC4, a Microchip 16F84A PIC controller.  The PIC contains 1024 bytes of flash memory for program storage, 68 bytes of static RAM, TTL level input and output pins, and ADC (Analog to Digital Converter) input pins.  JP5 provides in-circuit, low voltage programming of the PIC.  R18 is a pull down resistor for in-circuit programming selection.  LED3 and current limiting resistor R2 are connected to the PIC controller to provide a status or heart beat indicator.  Connections to external devices are made through a standard RS-232 DB-9 connector.  IC2 is a TTL to RS-232 level converter/buffer.  T1, T2, and T3 provide open drain drivers from the PIC controller.  Connection to external devices is made through JP2.  A LM34 temperature sensor provides an analog voltage of 10mV / degree Fahrenheit.  The on circuit board temperature is scaled by 2.4 with IC1A.  C5 provides a single pole, low pass filter to eliminate high frequency noise.  The temperature sensor is offset by 1.235V with VR1.  The offset allows the measurement of temperatures below 0 degrees Fahrenheit.  An external temperature input, using another LM34, is provided on JP4.  R17 and C15 provide filtering to the sensitive analog circuit.  The output of op-amp IC1 is supplied to the PIC controller.  In addition, the reference voltage, VR1, is also provided to the PIC controller to increase the dynamic range of the PIC ADC and allow for more accurate temperature measurements.  T4 provides an open drain output that is used to control the R/C (Radio Control) PWM (Pulse Width Modulation) servo.  The servo expects a PWM signal with a pulse width of 1 to 2mS and a PRI (Pulse Repetition Interval) of 50mS.  R13 provides a pull for the R/C servo.  16MHz XTAL1, C10, and C13 form the processor clock circuit. R6, R8, C19, and D4 provide an input voltage divider.  The input voltage is scaled to 0 to 5VDC for the PIC ADC.

Camera Control schematic.

NOTE: The schematic is saved as a standard GIF graphic file at 150 DPI (Dots Per Inch).  Although the image is very large, the file size is small (about 60K bytes).  For best quality, print the schematic on a single 8½ x 11" sheet of paper using your favorite graphics application.


Camera Control Firmware 

Copyright © 2001, KD7LMO

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

Link	Version	Description
	1.03	Camera Control Program in C
	2	GNU General Public License