# Comprehensive Brown Esper Photo Analyser ## Description Programmable CDI Controller (STM32F103, isolated pulser, SCR trigger, 4-layer automotive PCB) ## Project Details - **Owner:** hermanaa - **Created:** 3/13/2026 - **Last Updated:** 3/17/2026 - **Visibility:** Public - **Power Requirements:** USB-C sink-only 5V default; compatible with sources advertising 0.5A-3A; includes reverse/backfeed block, OVP, UVLO, OCP protection ahead of 3.3V rail - **Domain:** Consumer low-power environmental sensor node - **System Architecture:** flowchart TD subgraph InputProtection [Input Protection] VIN["10-15V Input"] --> FB1["Ferrite Bead"] --> TVS12["TVS 12V"] --> BUCK["Buck 3.3V"] end subgraph Logic [Logic Domain] BUCK --> V33["3V3 Rail"] --> MCU["STM32F103"] MCU --> TRIG["Trigger Output GPIO"] end subgraph PulserInput [Pulser Input Domain] PULSER["Pulser Input"] --> TVSP["TVS Pulser"] --> RC["RC Low Pass"] --> OPTO["PC817"] --> MCUIN["MCU Input"] end subgraph TriggerStage [SCR Trigger Stage] TRIG --> QSW["Switching Transistor"] --> RG["220R"] --> SCRG["To BT151 Gate"] end MCU --- GND["Ground Plane"] BUCK --- GND OPTO --- GND QSW --- GND - **Connectivity:** 2.4GHz 802.11 b/g/n Wi-Fi + BLE 5.x ## Key Components ### D1 — [SMBJ15A](https://www.flux.ai/adrian95/smbj15a.md) - Part Type: Diode - Manufacturer Part Number: SMBJ15A - Manufacturer Name: Littelfuse Inc. - License: https://creativecommons.org/licenses/by/4.0/ - Datasheet URL: https://www.littelfuse.com/~/media/electronics/datasheets/tvs_diodes/littelfuse_tvs_diode_smbj_datasheet.pdf.pdf - Role: TVS - Role Details: Transient suppression on 10-15V input - Package: SMBJ **Pins:** - A [pin 2] - K [pin 1] ### D2 — [24V Unidirectional TVS Diode](https://www.flux.ai/corynrobinson/24v-unidirectional-tvs-diode.md) - Breakdown Voltage: 26.7V - Part Type: Diode - Role Details: Pulser input transient suppression (unidirectional placeholder) - Role: TVS - Manufacturer Name: STMicroelectronics NV - Datasheet URL: https://octopart.com/datasheet/smaj24a-tr-stmicroelectronics-350001 - Leakage Current: 200nA - Package or Case Code: D_SMA - Package: SMA - Manufacturer Part Number: SMAJ24A-TR **Pins:** - A - K ### FB1 — [BLM31KN121SH1L](https://www.flux.ai/adrian95/blm31kn121sh1l.md) - Role Details: Ferrite bead series on 10-15V input - Part Type: Filter - Package: 1206 - License: https://creativecommons.org/licenses/by/4.0/ - Datasheet URL: https://www.murata.com/en-us/products/productdata/8801529495582/QNFA9148.pdf - Manufacturer Part Number: BLM31KN121SH1L - Manufacturer Name: Murata Electronics - Role: EMI Filter **Pins:** - 1 [pin 1] - 2 [pin 2] ### J1 — [Pin Header 01x08 2.54mm Horizontal](https://www.flux.ai/adrian95/pin-header-01x08-254mm-horizontal.md) - Role Details: Prototype harness header (KLX) - 2.54mm right-angle 1x8 - Package: THT - Part Type: Connector - Manufacturer Part Number: TBD-1x8-RA-2.54mm - License: https://creativecommons.org/licenses/by/4.0/ - Role: Connector - Manufacturer Name: Generic **Pins:** - Pin_1 [pin 1] - Pin_2 [pin 2] - Pin_3 [pin 3] - Pin_4 [pin 4] - Pin_5 [pin 5] - Pin_6 [pin 6] - Pin_7 [pin 7] - Pin_8 [pin 8] ### J2 — [2-644861-2](https://www.flux.ai/adrian95/2-644861-2.md) - Datasheet URL: https://www.te.com/commerce/DocumentDelivery/DDEController?Action=srchrtrv&DocNm=644861&DocType=Customer+Drawing&DocLang=English&PartCntxt=2-644861-2&DocFormat=pdf - Role Details: Trigger output to external SCR gate (BT151) - Role: Connector - Part Type: Connector - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Part Number: 2-644861-2 - Manufacturer Name: TE Connectivity AMP Connectors - Package: THT **Pins:** - Pin_1 [pin 1] - Pin_2 [pin 2] ### Q1 — [MMBT2222ALT3G](https://www.flux.ai/adrian95/mmbt2222alt3g.md) - Manufacturer Part Number: MMBT2222ALT3G - Role Details: Drives SCR gate through 220 ohm resistor - Datasheet URL: https://www.onsemi.com/pdf/datasheet/mmbt2222lt1-d.pdf - Manufacturer Name: onsemi - Part Type: Transistor - Role: Switch - License: https://creativecommons.org/licenses/by/4.0/ - Package: SOT-23 **Pins:** - B [pin 1] - C [pin 3] - E [pin 2] ### U1 — [MP1584EN-LF-P](https://www.flux.ai/adrian95/mp1584en-lf-p.md) - Role Details: 10-15V input to 3.3V rail for MCU - Manufacturer Part Number: MP1584EN-LF-P - Package: SOIC-8 EP - Manufacturer Name: Monolithic Power Systems Inc. - Role: Buck Regulator - Part Type: Integrated Circuit - License: https://creativecommons.org/licenses/by/4.0/ - Datasheet URL: https://www.mouser.com/datasheet/2/277/MP1584EN_LF_Z-2945524.pdf **Pins:** - BST [pin 8] - COMP [pin 3] - EN [pin 2] - FB [pin 4] - FREQ [pin 6] - GND [pin 5] - PAD [pin 9] - SW [pin 1] - VIN [pin 7] ### U2 — [PC817](https://www.flux.ai/kicad-part-library/pc817.md) - Role: Isolation - Package: DIP-4 - Role Details: Pulser input isolation to protect MCU from spikes - Package or Case Code: DIP-4_W7.62mm - Manufacturer Part Number: PC817 - Datasheet URL: http://www.soselectronic.cz/a_info/resource/d/pc817.pdf **Pins:** - ~ [pin 1] - ~ [pin 3] - ~ [pin 2] - ~ [pin 4] ### U3 — [KF128-5.08-2P-AA](https://www.flux.ai/lcsc/kf128-5p08-2p-aa.md) - LCSC Part Number: C474952 - Package: THT - Role Details: 10-15V input screw terminal - Connector Type: Screw terminal - Connector Rows: 1 - Operating Temperature: -40℃~+105℃ - Current Rating: 24A - Part Type: Screw terminal - Connector Gender: Female - Package or Case Code: CONN-TH_P5.08_KF128-5.08-2P - Datasheet URL: https://storage.googleapis.com/graviton-electric-symbols/document_assets/lcsc/2408211511_Cixi-Kefa-Elec-KF128-5-08-2P-AA_C474952.pdf - Product Info Url: https://lcsc.com/product-detail/New-Quadratic-Unclassified-Data_Cixi-Kefa-Elec-KF128-5-08-2P_C474952.html - Connector Positions: 2 - JLCPCB Part Class: Extended Part - Role: Connector - Manufacturer Part Number: KF128-5.08-2P-AA - Connector Pitch: 5.08mm - Manufacturer Name: KEFA(科发) **Pins:** - 1 [pin 1] - 2 [pin 2] ### U4 — [STM32F103C8T6](https://www.flux.ai/jharwinbarrozo/stm32f103c8t6.md) - Manufacturer Name: STMicroelectronics - Datasheet URL: https://datasheet.lcsc.com/lcsc/1811151642_STMicroelectronics-STM32F103C8T6_C8734.pdf - Package: LQFP-48 - Manufacturer Part Number: STM32F103C8T6 - Role: MCU - Role Details: STM32F103C8T6 72 MHz CDI controller; PA0 pulser EXTI, PA1 SCR trigger, PA9/PA10 UART - Part Type: Microcontroller **Pins:** - BOOT0 [pin 44] - NRST [pin 7] - PA0_WKUP [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_TAMPER_RTC [pin 2] - PC14_OSC32_IN [pin 3] - PC15_OSC32_OUT [pin 4] - PD0_OSC_IN [pin 5] - PD1_OSC_OUT [pin 6] - VBAT [pin 1] - VDD [pin 24] - VDD [pin 48] - VDD [pin 36] - VDDA [pin 9] - VSS [pin 23] - VSS [pin 47] - VSS [pin 35] - VSSA [pin 8] *The full schematic, PCB layout, bill of materials, and interactive design are available at [https://www.flux.ai/hermanaa/comprehensive-brown-esper-photo-analyser](https://www.flux.ai/hermanaa/comprehensive-brown-esper-photo-analyser).* --- *Generated from [https://www.flux.ai/hermanaa/comprehensive-brown-esper-photo-analyser](https://www.flux.ai/hermanaa/comprehensive-brown-esper-photo-analyser)*