Hardware Specification

Dimensions:

49.91 mm x 100.2 mm

IMU: IMU9250 - breakout GY-9250 via SPI

You can choose not to use this sensor and use wires to connect your sensors to SPI pins on the board.

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Baro: BMP-180 via I2C

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Current & Voltage Sensor: ADS1115 via I2C

The sensor has 4 sensing points. Only two is used to sens voltage and current as in APM & PIXHAWK. However this can be extended by software so that individual cells for 3S batteries are measured or to use the extra ADC pins in other functions.

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PWM Output: PCA9685 via I2C

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This module can output PWM signals upto 16 channels.

LED & Buzzer Driver: ULN2803APG

This IC is used to control LEDs & Buzzer. Each two outputs of the 8 outputs of the IC are wired up together so there are 4 output ports that support high current. OBAL uses only 2 leds not three and a buzzer. So there is an extra port that can be used.

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Switch:

This switch disables PWM output. It is not connected logically to Ardupilot. SO it is not the ARM switch of Ardupilot. It is a switch that disables PWM output by disabling PCA9685 using a chip enable pin.

Other Sensors:

All I2c & SPI sensors can be added easily to OBAL.

GPS can be connected to Serial-1 pins as they are connected to TX & RX of Raspberry-PI.

Telemetry can be connected via OTG in USB if you ar using Raspberry-Zero. Other Raspberry-PI's already contain multiple USB and can accept multiple GPS & Telemetry.