Page 14: of Marine Technology Magazine (July 2025)

LANDER LAB #15 by the CTD in the active mode. The A signi? cant advantage of Mega2560-

Firmware Development battery pack consists of 12 D-cell alka- Core are the numerous serial hardware The ? rmware for this system provides line batteries, (nominal 270 WH). An interfaces available. Each port is sup- a comprehensive solution for the high

Adafruit DS3231, a precision real-time ported by an individual universal asyn- sampling rate required when the lander time clock (RTC), is used for timekeep- chronous receiver/transmitter (UART) pro? les the water column down and ing, allowing for the synchronization of circuitry, providing reliable communica- back, and the low sampling rate required low frequency sampling and building a tion with serial peripherals. As with most when it reaches the seabed. As shown log ? le for the system. This RTC is tem- microcontrollers, the serial ports utilize in the ? owchart in Fig. 4, the user can perature compensated, offering high ac- TTL levels, 0–3.3V/5V. A SparkFun enable a premonitoring cycle to verify curacy, with a typical drift of 1 min per max3232 breakout board allows the con- the correct sampling of the sensors. To year. The I2C interface module includes version from TTL levels to the standard activate this function, the user toggles a coin cell, allowing the RTC to main- RS232, which is available on the inter- a reed switch using an external mag- tain data and time for at least two years faces of the CTD and the Oxygen sensor. net. Premonitoring can be run for hours without any external power. The RTC The third serial port is intended to sup- without power concerns because it per- consumes less than 0.1 mA powered by port communication with the host com- forms low-frequency sampling and en- the 3.3V power unit available in the sys- puter using either a Bluetooth modem or ters sleeping modes in between. When tem. Data is stored in a SanDisk Secure an external TTL/USB adapter. Thus, the removing the magnet, the system took

Digital Micro SD Card Industrial grade user can con? gure the system from a Se- samples on FastCat to determine the be- 16 GB microSD. As tested in this proj- rial Terminal or a Graphical User Inter- ginning of the downcast, which occurred ect, the SD Card requires less than 10 face (GUI) that can be built in the future. when the conductivity is greater than a mA during writing and up to 100 mA in Serial port 0 is reserved for accessing the user-de? ned threshold parameter. Simi- short periods when it is initialized. IDE when updating the ? rmware. larly, the CTD has an internal conductiv- ity threshold parameter that ensures that the pump is turned on only in saltwater.

Bench Testing

Extensive lab tests were used to evalu- ate the system design and conduct simu- lations under controlled conditions. The tests were performed in the laboratory to verify general functioning and to de- termine whether the data was properly stored in the microSD card.

At Sea Deployment

The ? rst Integrated Deep-Ocean Ob- servation System (IDOOS II) cruise was conducted from 27 September to 9 Oc- tober 2023 in the Antofagasta region on- board the RV Abate Molina. The main goal of this expedition was to deploy the ? rst deep-ocean observation system to study the physical, geological, and biological structures of the area. In ad- dition, the new lander was launched to con? rm improvements in electronic sys- tems and structural design, gather data on the physical variability of the water column, and obtain biological samples

Figure 2 from the Atacama Trench ? oor.

Wiring diagram of the main processor based on Atmega Mega2560-Core, and Throughout this ? rst research cruise, expansion boards. The system components have been selected for ef? cient only one lander launch was executed, energy consumption, from the microcontroller with an active mode consumption as the majority of tasks focused on de- of 59 and 0.6 mW in sleep mode. (Image by Victor Villagrán, UdeC) ploying two deepwater moorings in and 14 July/August 2025

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