Features

• periodically shots a photo allowing time lapse photography (can be combined with bulb mode), max time between photos: 99:59:59 (h:m:s),
• bulb time (maximum 99 h 59 m 59 s),
• postponed start (up to 24 h in advance),
• powered by 2 AA(A) batteries (3V),
• 2 × 16 characters LCD display + encoder for easy control,
• easy to use software,
• minimal number of components, small PCB,
• RTC clock (no calendar),
• low battery indicator.

Design

Device uses ATMEL's atmega168 micro controller (at the time of writing this ar

Features

• Controls max 3 DC motors
• Current up to 4A/motor
• Supply voltage up to 46V
• Current sensing
• PWM control
• Single sided PCB
• 15 pin Control Unit compatible header

After examining BLDC controllers available on the net (mostly for RC airplanes), I decided to design and build my own controller for robots.

Requirements

• Sensorless
• Max voltage: 12V
• Max current: 10A
• I²C for control
• RS232 (5V) for diagnostic and configuration
• No SMD parts
• Minimum additional elements
• ISP connector for programming

Controller is based on Atmel ATmega8 chip with limited number of external components. Preliminary design is finished.

Device was designed to be used as control unit for ROV or any other remotely controlled robot. As primary communication interface is used RS485. It allows controlling robot using 1200m long cable.
Several other interfaces allows reading data like temperature, depth and heading.

Normally ROV receives commands from the surface and sends back data read from sensors. Special software has to be written to perform this task.

Main features

• Atmel Atmega16 or Atmega32 microcontroller
• 1×RS485 for communication with surface
• 2×RS232 to control devices with serial interface, for example Roboteq motor controllers.
• 5×I²C header to connect any I²C device like CMPS03 digital compass, temperature sensors or BLDC controllers.
• 3×multi purpose header to be used as:
  • ADC input for sensors with voltage output, or
  • ADC input for sensors with current output like pressure sensor, or
  • digital input, or
  • digital output, or
  • servo controller
• 1-Wire bus
• LANC or IR interface to control camera
• 2×leak sensor
• ISP header to program microcontroller
• 15 pin header to connect Motor Controller
• Power voltage sensor
• JTAG support

One of the best methods to visualize ROV data is to show them as overlay on images from camera.
This project can be used in any ROV. It presents data read from sensors mixed with video signal from camera. It can read data from analog 4-20mA sensors and from I²C chips. Although project assume usage of specific sensors, any I²C or 4-20mA sensors can be used. Only software needs small modifications.

RS485 is an alternatve for RS232 for long distances. Maximum length of the cable for RS232 is only 15m. For RS485 it is about 1200m. In addition you can connect many devices to RS485 bus (unlike RS232 -- only 2).

Converter is intended to use with PC computer to communicate with ROV using 2 wires in half duplex mode. Send/receive mode is selected by RTS signal. The converter was designed to be as simple as possible, so it has no some features that can be found in commercial grade products (e.g. galvanic separation).

I do not describe here RS485 standard, for more information and how to use RS485 with micro controller please read RS485 article.

Overview

Popular chip MAX232 is used to convert RS232 signals from/to TTL level.

Features

• I²C bus, only 2 microcontroller lines are required
• 8 independent channels, each 500mA (650mA peak)
• Output can be paralleled
• Controls 2 unipolar steppers 500mA/phase or 1 stepper 1000mA/phase
• Selectable I²C address
• Externally powered (50V max) or 5V from I²C header
• Simple small single sided PCB
• Based on cheap and popular ICs