# Smartotum Alarm ## Description Welcome to your new project. Imagine what you can build here. ## Project Details - **Owner:** lrodorigo - **Created:** 3/1/2026 - **Last Updated:** 3/1/2026 - **Visibility:** Public - **System Architecture:** flowchart TD A["12V Field Wiring"] --> B["Input Protection and Scaling x16"] B --> C["16ch Analog Mux"] C --> D["STM32 MCU I2C Slave + ADC"] D --> E["Banana Pi 40pin Header I2C Master"] F["12V Input Connector"] --> G["Input Protection Fuse TVS Reverse Polarity"] G --> H["Buck Regulator 12V to 3.3V"] H --> D H --> C G --> I["12V Monitor Divider"] I --> D D --> J["Relay Drivers x4"] J --> K["DIL Relays x4 NO NC COM Outputs"] L["NC Loop Inputs x4"] --> M["ESD EMI Filter and Clamp x4"] M --> D ## Key Components ### D1 — [SMBJ12CA-TR](https://www.flux.ai/lcsc/smbj12ca-tr.md) - Datasheet URL: https://storage.googleapis.com/graviton-electric-symbols/document_assets/lcsc/2304140030_STMicroelectronics-SMBJ12CA-TR_C435931.pdf - Manufacturer Name: ST(意法半导体) - Package: SMB - Role: Protection - Product Info Url: https://lcsc.com/product-detail/TVS_STMicroelectronics-SMBJ12CA-TR_C435931.html - Role Details: TVS at 12V input connector for surge/ESD - Manufacturer Part Number: SMBJ12CA-TR - Package or Case Code: SMB_L4.6-W3.6-LS5.3-BI - Part Type: TVS - JLCPCB Part Class: Extended Part - LCSC Part Number: C435931 **Pins:** - 1 [pin 1] - 2 [pin 2] ### D2 — [PESD3V3L4UG](https://www.flux.ai/kicad-part-library/pesd3v3l4ug.md) - Package or Case Code: SOT-353_SC-70-5 - Role: Protection - Datasheet URL: https://assets.nexperia.com/documents/data-sheet/PESDXL4UF_G_W.pdf - Role Details: Low-capacitance ESD diode array for 3.3V digital lines - Manufacturer Part Number: PESD3V3L4UG - Manufacturer Name: Texas Instruments Inc. - Package: SOT-353 **Pins:** - A [pin 2] - K1 [pin 1] - K2 [pin 3] - K3 [pin 4] - K4 [pin 5] ### D3 — [PESD3V3L4UG](https://www.flux.ai/kicad-part-library/pesd3v3l4ug.md) - Package or Case Code: SOT-353_SC-70-5 - Datasheet URL: https://assets.nexperia.com/documents/data-sheet/PESDXL4UF_G_W.pdf - Role: Protection - Manufacturer Part Number: PESD3V3L4UG - Package: SOT-353 - Manufacturer Name: Texas Instruments Inc. - Role Details: Low-capacitance ESD diode array for 3.3V digital lines **Pins:** - A [pin 2] - K1 [pin 1] - K2 [pin 3] - K3 [pin 4] - K4 [pin 5] ### D4 — [SMBJ12CA-TR](https://www.flux.ai/lcsc/smbj12ca-tr.md) - Manufacturer Part Number: SMBJ12CA-TR - JLCPCB Part Class: Extended Part - LCSC Part Number: C435931 - Package: SMB - Package or Case Code: SMB_L4.6-W3.6-LS5.3-BI - Part Type: TVS - Datasheet URL: https://storage.googleapis.com/graviton-electric-symbols/document_assets/lcsc/2304140030_STMicroelectronics-SMBJ12CA-TR_C435931.pdf - Role: Protection - Role Details: TVS at 12V input connector for surge/ESD - Product Info Url: https://lcsc.com/product-detail/TVS_STMicroelectronics-SMBJ12CA-TR_C435931.html - Manufacturer Name: ST(意法半导体) **Pins:** - 1 [pin 1] - 2 [pin 2] ### D5 — [PESD3V3L4UG](https://www.flux.ai/kicad-part-library/pesd3v3l4ug.md) - Role: Protection - Package or Case Code: SOT-353_SC-70-5 - Datasheet URL: https://assets.nexperia.com/documents/data-sheet/PESDXL4UF_G_W.pdf - Package: SOT-353 - Manufacturer Part Number: PESD3V3L4UG - Role Details: Low-capacitance ESD diode array for 3.3V digital lines - Manufacturer Name: Texas Instruments Inc. **Pins:** - A [pin 2] - K1 [pin 1] - K2 [pin 3] - K3 [pin 4] - K4 [pin 5] ### D6 — [PESD3V3L4UG](https://www.flux.ai/kicad-part-library/pesd3v3l4ug.md) - Role: Protection - Package or Case Code: SOT-353_SC-70-5 - Datasheet URL: https://assets.nexperia.com/documents/data-sheet/PESDXL4UF_G_W.pdf - Package: SOT-353 - Manufacturer Part Number: PESD3V3L4UG - Role Details: Low-capacitance ESD diode array for 3.3V digital lines - Manufacturer Name: Texas Instruments Inc. **Pins:** - A [pin 2] - K1 [pin 1] - K2 [pin 3] - K3 [pin 4] - K4 [pin 5] ### IC1 — [LMR33620ARNXT](https://www.flux.ai/adrian95/lmr33620arnxt.md) - Manufacturer Part Number: LMR33620ARNXT - Role: Regulator - Package or Case Code: LMR33620ARNXT - Role Details: 12V input buck regulator generating 3.3V rail for MCU and mux - Datasheet URL: http://www.ti.com/lit/gpn/lmr33620 - Part Type: Integrated Circuit - Package: WSON-8 - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Name: Texas Instruments **Pins:** - AGND [pin 6] - BOOT [pin 4] - EN [pin 9] - FB [pin 7] - NC [pin 3] - PG [pin 8] - PGND_1 [pin 1] - PGND_2 [pin 11] - SW [pin 12] - VCC [pin 5] - VIN_1 [pin 2] - VIN_2 [pin 10] ### IC2 — [LMR33620ARNXT](https://www.flux.ai/adrian95/lmr33620arnxt.md) - Manufacturer Part Number: LMR33620ARNXT - Role: Regulator - Role Details: 12V input buck regulator generating 3.3V rail for MCU and mux - Package or Case Code: LMR33620ARNXT - Datasheet URL: http://www.ti.com/lit/gpn/lmr33620 - Manufacturer Name: Texas Instruments - License: https://creativecommons.org/licenses/by/4.0/ - Package: WSON-8 - Part Type: Integrated Circuit **Pins:** - AGND [pin 6] - BOOT [pin 4] - EN [pin 9] - FB [pin 7] - NC [pin 3] - PG [pin 8] - PGND_1 [pin 1] - PGND_2 [pin 11] - SW [pin 12] - VCC [pin 5] - VIN_1 [pin 2] - VIN_2 [pin 10] ### J1 — [ARM JTAG SWD 10Pin 0.05" Connector](https://www.flux.ai/vasy_skral/arm-jtag-swd-10pin-005-connector.md) - Package: 2x5 1.27mm - Manufacturer Part Number: FTSH-105-01-L-DV-007-K - Role Details: SWDIO/SWCLK/NRST/3V3/GND programming header - Datasheet URL: https://suddendocs.samtec.com/catalog_english/ftsh_smt.pdf - Role: Debug - Part Type: Connector - Manufacturer Name: Analog Devices **Pins:** - ~RESET~ [pin 10] - GND [pin 5] - GND [pin 3] - GNDDetect [pin 9] - NC/TDI [pin 8] - SWDCLK/TCK [pin 4] - SWDIO/TMS [pin 2] - SWO/TDO [pin 6] - VTref [pin 1] ### J2 — [ARM JTAG SWD 10Pin 0.05" Connector](https://www.flux.ai/vasy_skral/arm-jtag-swd-10pin-005-connector.md) - Datasheet URL: https://suddendocs.samtec.com/catalog_english/ftsh_smt.pdf - Manufacturer Part Number: FTSH-105-01-L-DV-007-K - Role: Debug - Manufacturer Name: Analog Devices - Part Type: Connector - Role Details: SWDIO/SWCLK/NRST/3V3/GND programming header - Package: 2x5_1.27mm **Pins:** - ~RESET~ [pin 10] - GND [pin 5] - GND [pin 3] - GNDDetect [pin 9] - NC/TDI [pin 8] - SWDCLK/TCK [pin 4] - SWDIO/TMS [pin 2] - SWO/TDO [pin 6] - VTref [pin 1] ### U1 — [STM32F030C8Tx](https://www.flux.ai/kicad-part-library/stm32f030c8tx.md) - Package: LQFP-48 - Package or Case Code: LQFP-48_7x7mm_P0.5mm - Role: Controller - Manufacturer Part Number: STM32F030C8Tx - Manufacturer Name: STMicroelectronics NV - Role Details: STM32F0 SPI slave + ADC for dual mux + GPIO for relays and loop inputs - Datasheet URL: https://www.st.com/resource/en/datasheet/stm32f030c8.pdf **Pins:** - BOOT0 [pin 44] - NRST [pin 7] - PA0 [pin 10] - PA1 [pin 11] - PA10 [pin 31] - PA11 [pin 32] - PA12 [pin 33] - PA13 [pin 34] - PA14 [pin 37] - PA15 [pin 38] - PA2 [pin 12] - PA3 [pin 13] - PA4 [pin 14] - PA5 [pin 15] - PA6 [pin 16] - PA7 [pin 17] - PA8 [pin 29] - PA9 [pin 30] - PB0 [pin 18] - PB1 [pin 19] - PB10 [pin 21] - PB11 [pin 22] - PB12 [pin 25] - PB13 [pin 26] - PB14 [pin 27] - PB15 [pin 28] - PB2 [pin 20] - PB3 [pin 39] - PB4 [pin 40] - PB5 [pin 41] - PB6 [pin 42] - PB7 [pin 43] - PB8 [pin 45] - PB9 [pin 46] - PC13 [pin 2] - PC14 [pin 3] - PC15 [pin 4] - PF0 [pin 5] - PF1 [pin 6] - PF6 [pin 35] - PF7 [pin 36] - VDD [pin 24] - VDD [pin 48] - VDD [pin 1] - VDDA [pin 9] - VSS [pin 47] - VSS [pin 23] - VSSA [pin 8] ### U2 — [CD74HC4067M](https://www.flux.ai/kicad-part-library/cd74hc4067m.md) - Package or Case Code: SOIC-24W_7.5x15.4mm_P1.27mm - Manufacturer Part Number: CD74HC4067M - Datasheet URL: http://www.ti.com/lit/ds/symlink/cd74hc4067.pdf - Role Details: 16-channel mux to route scaled alarm channels to ADC - Role: Analog Mux - Manufacturer Name: Texas Instruments Inc. - Package: SOIC-24 **Pins:** - ~{E} [pin 15] - COM [pin 1] - GND [pin 12] - I0 [pin 9] - I1 [pin 8] - I10 [pin 21] - I11 [pin 20] - I12 [pin 19] - I13 [pin 18] - I14 [pin 17] - I15 [pin 16] - I2 [pin 7] - I3 [pin 6] - I4 [pin 5] - I5 [pin 4] - I6 [pin 3] - I7 [pin 2] - I8 [pin 23] - I9 [pin 22] - S0 [pin 10] - S1 [pin 11] - S2 [pin 14] - S3 [pin 13] - VCC [pin 24] ### U3 — [ULN2003A](https://www.flux.ai/adrian95/uln2003a.md) - Part Type: Integrated Circuit - License: https://creativecommons.org/licenses/by/4.0/ - Role Details: Drives 12V relay coils from STM32 GPIO - Manufacturer Name: STMicroelectronics - Package: DIP-16 - Manufacturer Part Number: ULN2003A - Role: Driver - Datasheet URL: https://www.st.com/content/ccc/resource/technical/document/datasheet/f3/6e/c8/64/4d/b3/4e/38/CD00001244.pdf/files/CD00001244.pdf/jcr:content/translations/en.CD00001244.pdf **Pins:** - COM [pin 9] - GND [pin 8] - I1 [pin 1] - I2 [pin 2] - I3 [pin 3] - I4 [pin 4] - I5 [pin 5] - I6 [pin 6] - I7 [pin 7] - O1 [pin 16] - O2 [pin 15] - O3 [pin 14] - O4 [pin 13] - O5 [pin 12] - O6 [pin 11] - O7 [pin 10] ### U5 — [CD74HC4067M](https://www.flux.ai/kicad-part-library/cd74hc4067m.md) - Package: SOIC24 - Manufacturer Name: Texas Instruments Inc. - Datasheet URL: http://www.ti.com/lit/ds/symlink/cd74hc4067.pdf - Manufacturer Part Number: CD74HC4067M - Role: Analog Mux - Package or Case Code: SOIC-24W_7.5x15.4mm_P1.27mm - Role Details: 16-channel mux to route scaled alarm channels to ADC **Pins:** - ~{E} [pin 15] - COM [pin 1] - GND [pin 12] - I0 [pin 9] - I1 [pin 8] - I10 [pin 21] - I11 [pin 20] - I12 [pin 19] - I13 [pin 18] - I14 [pin 17] - I15 [pin 16] - I2 [pin 7] - I3 [pin 6] - I4 [pin 5] - I5 [pin 4] - I6 [pin 3] - I7 [pin 2] - I8 [pin 23] - I9 [pin 22] - S0 [pin 10] - S1 [pin 11] - S2 [pin 14] - S3 [pin 13] - VCC [pin 24] ### U6 — [ULN2003A](https://www.flux.ai/adrian95/uln2003a.md) - Datasheet URL: https://www.st.com/content/ccc/resource/technical/document/datasheet/f3/6e/c8/64/4d/b3/4e/38/CD00001244.pdf/files/CD00001244.pdf/jcr:content/translations/en.CD00001244.pdf - Manufacturer Part Number: ULN2003A - Part Type: Integrated Circuit - Package: DIP16 - Manufacturer Name: STMicroelectronics - Role Details: Drives 12V relay coils from STM32 GPIO - License: https://creativecommons.org/licenses/by/4.0/ - Role: Driver **Pins:** - COM [pin 9] - GND [pin 8] - I1 [pin 1] - I2 [pin 2] - I3 [pin 3] - I4 [pin 4] - I5 [pin 5] - I6 [pin 6] - I7 [pin 7] - O1 [pin 16] - O2 [pin 15] - O3 [pin 14] - O4 [pin 13] - O5 [pin 12] - O6 [pin 11] - O7 [pin 10] ### U7 — [ISO7741DWR](https://www.flux.ai/lcsc/iso7741dwr.md) - Package: SOIC-16 - Part Type: Digital Isolators - Manufacturer Part Number: ISO7741DWR - LCSC Part Number: C571196 - Role Details: Quad-channel digital isolator for SPI: SCK, MOSI, MISO, CS - JLCPCB Part Class: Extended Part - Package or Case Code: SOIC-16_L10.3-W7.5-P1.27-LS10.3-BL - Product Info Url: https://lcsc.com/product-detail/Digital-Isolators_Texas-Instruments-Texas-Instruments-ISO7741DWR_C571196.html - Role: Isolation - Manufacturer Name: TI(德州仪器) - Datasheet URL: https://storage.googleapis.com/graviton-electric-symbols/document_assets/lcsc/2410010202_Texas-Instruments-ISO7741DWR_C571196.pdf **Pins:** - EN1 [pin 7] - EN2 [pin 10] - GND1 [pin 2] - GND1 [pin 8] - GND2 [pin 9] - GND2 [pin 15] - INA [pin 3] - INB [pin 4] - INC [pin 5] - IND [pin 11] - OUTA [pin 14] - OUTB [pin 13] - OUTC [pin 12] - OUTD [pin 6] - VCC1 [pin 1] - VCC2 [pin 16] ### U8 — [STM32F030C8Tx](https://www.flux.ai/kicad-part-library/stm32f030c8tx.md) - Role: Controller - Datasheet URL: https://www.st.com/resource/en/datasheet/stm32f030c8.pdf - Role Details: STM32F0 SPI slave + ADC for dual mux + GPIO for relays and loop inputs - Package: LQFP-48 - Manufacturer Part Number: STM32F030C8Tx - Manufacturer Name: STMicroelectronics NV - Package or Case Code: LQFP-48_7x7mm_P0.5mm **Pins:** - BOOT0 [pin 44] - NRST [pin 7] - PA0 [pin 10] - PA1 [pin 11] - PA10 [pin 31] - PA11 [pin 32] - PA12 [pin 33] - PA13 [pin 34] - PA14 [pin 37] - PA15 [pin 38] - PA2 [pin 12] - PA3 [pin 13] - PA4 [pin 14] - PA5 [pin 15] - PA6 [pin 16] - PA7 [pin 17] - PA8 [pin 29] - PA9 [pin 30] - PB0 [pin 18] - PB1 [pin 19] - PB10 [pin 21] - PB11 [pin 22] - PB12 [pin 25] - PB13 [pin 26] - PB14 [pin 27] - PB15 [pin 28] - PB2 [pin 20] - PB3 [pin 39] - PB4 [pin 40] - PB5 [pin 41] - PB6 [pin 42] - PB7 [pin 43] - PB8 [pin 45] - PB9 [pin 46] - PC13 [pin 2] - PC14 [pin 3] - PC15 [pin 4] - PF0 [pin 5] - PF1 [pin 6] - PF6 [pin 35] - PF7 [pin 36] - VDD [pin 24] - VDD [pin 48] - VDD [pin 1] - VDDA [pin 9] - VSS [pin 47] - VSS [pin 23] - VSSA [pin 8] *The full schematic, PCB layout, bill of materials, and interactive design are available at [https://www.flux.ai/lrodorigo/smartotum-alarm](https://www.flux.ai/lrodorigo/smartotum-alarm).* --- *Generated from [https://www.flux.ai/lrodorigo/smartotum-alarm](https://www.flux.ai/lrodorigo/smartotum-alarm)*