Altimeter v2

Altimeter_v2

Intervalometer with serial interface based on Mega2560 MCU

Current application:

• Intervalometer for photogrammetry surveys (triggering a Canon 5DsR DSLR every second)
• Real-time sensor feedback underwater (through attached OLED display):
  • Levelling and altitude (through 2 x altimeters: BlueRobotics Ping Sonar)
  • Read-out USBL communications (through BluePrint Subsea X150 USBL)
  • Depth and "bottom-depth" based on altitude (through BlueRobotics Depth Sensor)
  • Stopwatch & intervalometer count (triggered by Remora remote)
• Logging synchronized sensor data on SD card

Features:

• Real-time clock (RTC) for timekeeping
• SD-card reader to log sensor data
• 4-Channel Optocoupler to trigger camera(s)
• Step-down regulator to run board & DSLR camera off external battery (e.g. from dive propulsion vehicle)
• Supports I2C (3.3V or 5V logic), UART and RS232 sensors
• Connectors for remote controller & I2C or SPI display
• Headers to connect with Robotdyn MCU-PRO Mega 2560 board, which can be programmed using Arduino IDE
• Fits inside BlueRobotics 2" watertight enclosure (see image below)

Schematic

PDF Schematic

• Note: LP3966 on schematic replaced with TL1963AKTTRG3 (has the same footprint)

Arduino code

Arduino code (some features are currently commented out)

PCB Design

KiCad PCB file / Bill of materials

• Note: footprint of the XC1195CT-ND Crystal turned out to be incorrect, but could easily remedied with direct bridge to RTC pin

Underwater housing

Image shows board installed in a BlueRobotics 2" watertight enclosure, and with a 20x4 OLED display connected. On the left side, there are penetrators for an on/off switch, a BlueRobotics Depth Sensor, and 2 x BlueRobotics Ping Sonar (although on the photo only one connected, hence the "error" on the top-right of the display). On the right side, there is an Ikelite connector to connect with the camera (power and trigger), another Ikelite connector for the 3-button remote (Remora), a penetrator for a cable connecting with the Dive-Xtras Piranha DPV battery, and a penetrator for the cable connecting with the BluePrint Subsea X150 USBL.

Final notes

Acknowledging John Atkins for all the design advice! Currently working on next iteration with SAMD51 integrated on the board (no external controller board required).