# Moral Indigo Electronic Thumb ## Description Industrial 1-Wire to I2C Node (DS28E18) with left-side I2C header J3 (3V3,GND,SDA,SCL) and right-side trunk pass-through (VPLUS,DQ,GND) incl. 33Ω series + TVS on DQ and 4.7k I2C pull-ups, plus test pads (DQ,3V3,GND). ## Project Details - **Owner:** lbrandjord - **Created:** 2/15/2026 - **Last Updated:** 2/16/2026 - **Visibility:** Public - **System Architecture:** flowchart TD Trunk_IN["Trunk IN 3-wire\nVplus DQ GND"] --> PassThrough["Pass-through\nTop and bottom terminals"] PassThrough --> Trunk_OUT["Trunk OUT 3-wire\nVplus DQ GND"] PassThrough -->|"Vplus"| Local_3V3["Local 3.3V rail"] PassThrough -->|"DQ"| DQ_Protect["DQ protection\nTVS to GND + 33ohm series"] PassThrough -->|"GND"| GNDNet["GND"] DQ_Protect --> Bridge["DS28E18\n1-Wire to I2C bridge"] Local_3V3 --> Bridge GNDNet --> Bridge Bridge -->|"I2C SDA SCL"| Sensor["SHT85\nHumidity and Temp"] Local_3V3 --> Sensor GNDNet --> Sensor Local_3V3 --> Pullups["I2C pullups\n4.7k to 3.3V"] Pullups --> Sensor TestPads["Test pads\nDQ 3V3 GND"] --- PassThrough TestPads --- Local_3V3 TestPads --- GNDNet AltSensor["Alt BOM\nDS18B20 1-Wire temp"] -. "Variant" .-> PassThrough - **Design Notes:** Orientation/placement intent: - Left side (I2C group): place U1 (SHT85) and J3 (I2C sensor header) together on the left edge. - Place IC1 (DS28E18) adjacent to the I2C group, with short I2C_SCL/I2C_SDA routing. - Right side (1-Wire trunk): place J1 as Trunk OUT on the right edge; place J2 as Trunk IN on the left edge. - Maintain 1-Wire pass-through on TRUNK_DQ between J2 PIN2 and J1 PIN2, with series protection R1 between TRUNK_DQ and IC1 IO (DQ_PROTECTED). ## Key Components ### IC1 — [DS28E18Q+T](https://www.flux.ai/jecstronic/ds28e18qplust.md) - Role: Bridge - Manufacturer Part Number: DS28E18Q+T - Datasheet URL: https://www.analog.com/media/en/technical-documentation/data-sheets/ds28e18.pdf - Manufacturer Name: Analog Devices Inc./Maxim Integrated - Part Type: Integrated Circuit - Role Details: DS28E18 1-Wire to I2C bridge - License: https://creativecommons.org/licenses/by/4.0/ **Pins:** - CEXT [pin 8] - EP [pin 9] - GND [pin 4] - GPIOA/SS# [pin 1] - GPIOB/MISO [pin 5] - IO [pin 3] - SCL/SCLK [pin 6] - SDA/MOSI [pin 7] - SENS_VDD [pin 2] ### J1 — [1712805](https://www.flux.ai/adrian95/1712805.md) - Datasheet URL: http://www.phoenixcontact.com/de/produkte/1712805/pdf - Role Details: 1-Wire trunk 4-pos connector (VPLUS,DQ,GND,NC) - Manufacturer Part Number: 1712805 - Package or Case Code: 1712805 - License: https://creativecommons.org/licenses/by/4.0/ - Role: Trunk connector - Manufacturer Name: Phoenix Contact - Part Type: Connector **Pins:** - 1 [pin 1] - 2 [pin 2] - 3 [pin 3] - 4 [pin 4] ### J2 — [1712805](https://www.flux.ai/adrian95/1712805.md) - Role Details: 1-Wire trunk 4-pos connector (VPLUS,DQ,GND,NC) - Manufacturer Name: Phoenix Contact - Part Type: Connector - Role: Trunk connector - License: https://creativecommons.org/licenses/by/4.0/ - Package or Case Code: 1712805 - Datasheet URL: http://www.phoenixcontact.com/de/produkte/1712805/pdf - Manufacturer Part Number: 1712805 **Pins:** - 1 [pin 1] - 2 [pin 2] - 3 [pin 3] - 4 [pin 4] ### U1 — [SHT85](https://www.flux.ai/jecstronic/sht85.md) - Manufacturer Name: Sensirion AG - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Part Number: SHT85 - Datasheet URL: https://developer.sensirion.com/fileadmin/user_upload/customers/sensirion/Dokumente/2_Humidity_Sensors/Datasheets/Sensirion_Humidity_Sensors_SHT85_Datasheet.pdf - Part Type: Sensor **Pins:** - SCL [pin 1] - SDA [pin 4] - VDD [pin 2] - VSS [pin 3] *The full schematic, PCB layout, bill of materials, and interactive design are available at [https://www.flux.ai/lbrandjord/moral-indigo-electronic-thumb](https://www.flux.ai/lbrandjord/moral-indigo-electronic-thumb).* --- *Generated from [https://www.flux.ai/lbrandjord/moral-indigo-electronic-thumb](https://www.flux.ai/lbrandjord/moral-indigo-electronic-thumb)*