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Each node consists of a main environment board + sensor breakout board
Main environment board - interfaces with a PSOM (Peripheral System on Module) to provide ADC, I2C, and CAN functionality; connects to breakout board via short (TODO: absolute wire size/constraints after testing) wire
Sensor breakout board - implements exposed humidity, airflow, and temperature sensors with all passive components and a connector to interface with the main environment board
Modularity - can pick and choose which sensors to use on each breakout board during assembly
Not all sensors need to be present at every node
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Context
Location of the board: Several boards Boards will be located utilized by several systems throughout the car as outlined below
Cooling
Nose Intake, Tail Exhaust, Battery box intake/exhaust, internally in battery box multiple locations
any TODO: Any other systems needing environmental sensing TBD
Connection List
# | Name | Type | Ideal Voltage | Notes |
|---|---|---|---|---|
U4 | Daughterboard Connector | 53307-2471 (PSOM) | N/A | 3.65mm tall |
J2 | CAN Output | 1x4xP3.00mm_PolarizingPeg_Vertical | +12V | 6.98mm tall |
J3 | CAN Input | 1x4xP3.00mm_PolarizingPeg_Vertical | +12V | 6.98mm tall |
J6 | Breakout Connector | 2x05_P2.50mm_Vertical | +3.3V | 9.05mm tall |
PeripheralSOM Daughterboard Connection List
Pin # | Net Name | Notes |
|---|---|---|
2, 9 | +3.3V | General 3.3V source for SHT45 humidity sensor and FS3000 airflow sensor |
4, 11 | GND | Ground associated with general 3.3V source |
6 | I2C2_SDA | I2C data signal for FS3000 airflow sensor |
8 | I2C2_SCL | I2C clock signal for FS3000 airflow sensor |
10 | VDDA (3.3V) | Isolated 3.3V analog voltage source for LMT87 temperature sensor |
12 | GNDA | Isolated analog ground for LMT87 temperature sensor |
14 | I2C1_SCL | I2C clock signal for SHT45 humidity sensor |
16 | I2C1_SDA | I2C data signal for SHT45 humidity sensor |
20 | PA1 (ADC) | STM32 analog-to-digital converter input on PSOM; connected to analog output of LMT87 temperature sensor |
21 | CAN_L | CAN Bus Low; connected to other Environment boards and Leader board over EnvironmentCAN |
22 | +12V_In | 12V input from CAN I/O connector |
23 | CAN_H | CAN Bus High; connected to other Environment boards and Leader board over EnvironmentCAN |
24 | GNDPWR | Ground associated with 12V from CAN I/O connector |
| Note |
|---|
I2C2 jumpers on Peripheral SOM PeripheralSOM must be closed for pull-up functionality (default is open for GPIO) |
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Sensor Schematics
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| Note |
|---|
R1 and C7 values were chosen arbitrarily due to lack of documentation, need to test/verify |
Protection for Breakout Board
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Main Board
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Connectors
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Breakout Connector
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List of Circuit Components
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