# Sophisticated Beige Gadget Copter ## Description Tiny MSR Card Reader - Always-On Battery Low Power, Encrypted Storage + Encrypted SMS ## Project Details - **Owner:** ov2319 - **Created:** 2/25/2026 - **Last Updated:** 2/25/2026 - **Visibility:** Public - **Power Integrity Notes:** SIM800C VBAT bulk: add low-ESR bulk caps C5/C6 close to U1 VBAT pins. Voltage derating rule: operate at <=60% of r ated voltage (use >=10 V parts on 4.2 V max VBAT). Keep existing 0.1 uF, 2.2 uF, 10 uF network close to VBAT pins in parallel. - **Power Supply Settings:** VBAT is an always-on battery rail (3.7V nominal) and is ERC-driven by PowerNet1. GND return via J1 Pin_2. - **VBAT Driven Supply:** Yes - driven by PowerNet1 (Power Net Portal) at 3.7V - **Power Tree:** Always-on VBAT: J1 Pin_1 -> VBAT net -> U1(VBAT pins 34,35 + VDD_EXT), U2(VBAT + VDD + VDDA + VCAP_1), U3(VCC), IC1(VCC). GND return via J1 Pin_2 -> GND net. Legacy power gating removed (R3, C9 removed; no PWR_EN net). - **Always-on VBAT Change Log:** 2026-02-25: Removed load-switch remnants (R3, C9) and consolidated supply as always-on VBAT. Next: mark VBAT as driven supply (power flag / net type Power + Voltage property) and delete any leftover PWR_EN net/portals if present. - **System Architecture:** flowchart TD Bat["Battery"] --> Vbat["VBAT always on"] Vbat --> U1["SIM800C modem"] Vbat --> U2["STM32F423 MCU"] Vbat --> U3["ATECC608A secure element"] Vbat --> IC1["W25Q32 SPI flash"] U2 -->|UART| U1 U2 -->|I2C| U3 U2 -->|SPI| IC1 U2 --> Flow["Read card -> encrypt -> store"] U1 --> SmsIn["Incoming SMS cmd"] SmsIn --> U2 U2 --> SmsOut["Encrypt payload -> SMS send"] SmsOut --> U1 ## Key Components ### D1 — [PESD3V3L5UY](https://www.flux.ai/kicad-part-library/pesd3v3l5uy.md) - Manufacturer Part Number: PESD3V3L5UY - Package: SOT-363 - Role: ESD Protection - Role Details: ESD clamp for SIM_DATA/SIM_CLK/SIM_RST/SIM_DET (and spare) at J2 - Datasheet URL: https://assets.nexperia.com/documents/data-sheet/PESDXL5UF_V_Y.pdf - Package or Case Code: SOT-363_SC-70-6 - Manufacturer Name: Texas Instruments Inc. **Pins:** - A [pin 2] - K1 [pin 1] - K2 [pin 3] - K3 [pin 4] - K4 [pin 5] - K5 [pin 6] ### IC1 — [W25Q32JVZPIM](https://www.flux.ai/adrian95/w25q32jvzpim.md) - License: https://creativecommons.org/licenses/by/4.0/ - Part Type: Integrated Circuit - Role: Nonvolatile Storage - Manufacturer Part Number: W25Q32JVZPIM - Role Details: Stores encrypted swipe records (file-like log) - Datasheet URL: https://www.winbond.com/resource-files/w25q32jv_dtr%20revh%20010172019%20plus.pdf - Package: WSON-8_6x5mm - Manufacturer Name: Winbond **Pins:** - ~CS [pin 1] - ~HOLD_OR_RESET_(IO3) [pin 7] - ~WP_(IO2) [pin 3] - CLK [pin 6] - DI_(IO0) [pin 5] - DO_(IO1) [pin 2] - EP [pin 9] - GND [pin 4] - VCC [pin 8] ### J1 — [Pin Header 01x08 2.54mm Vertical](https://www.flux.ai/adrian95/pin-header-01x08-254mm-vertical.md) - Package: PinHeader_1x08_P2.54mm_Vertical - Part Type: Connector - License: https://creativecommons.org/licenses/by/4.0/ - Role Details: Battery/control header (manufacturable) - Role: Connector **Pins:** - 1 [pin 1] - 2 [pin 2] - 3 [pin 3] - 4 [pin 4] - 5 [pin 5] - 6 [pin 6] - 7 [pin 7] - 8 [pin 8] ### J2 — [0901301106](https://www.flux.ai/adrian95/0901301106.md) - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Name: Molex - Manufacturer Part Number: 0901301106 - Package: PinHeader_1x06_P2.54mm_Vertical - Role: Connector - Role Details: SIM interface header placeholder (manufacturable MPN) - Part Type: Connector - Datasheet URL: https://tools.molex.com/pdm_docs/sd/901301106_sd.pdf **Pins:** - 1 [pin 1] - 2 [pin 2] - 3 [pin 3] - 4 [pin 4] - 5 [pin 5] - 6 [pin 6] ### J3 — [Connector 02x03](https://www.flux.ai/adrian95/connector-02x03.md) - Manufacturer Part Number: Conn_02x03_Counter_Clockwise - Package: PinHeader_2x03_P2.54mm_Vertical - Role: Connector - Role Details: SWD debug/programming header **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] ### Q1 — [MMBT3904LT1G](https://www.flux.ai/openpartlist/mmbt3904lt1g.md) - Datasheet URL: https://www.onsemi.com/pdf/datasheet/mmbt3904lt1-d.pdf - Manufacturer Part Number: MMBT3904LT1G - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Name: onsemi - Role Details: PWRKEY low-side pull transistor for SIM800C - Part Type: Transistor - Role: Level Shift/Driver - Package: SOT-23-3 **Pins:** - B [pin 1] - C [pin 3] - E [pin 2] ### TP_GND1 — [1.25mm SMD Test Point](https://www.flux.ai/jharwinbarrozo/1p25mm-smd-test-point.md) - Package: SMD - Role: Test Point - Role Details: GND return access pad, 1.25mm **Pins:** - P1 ### TP_GND2 — [1.25mm SMD Test Point](https://www.flux.ai/jharwinbarrozo/1p25mm-smd-test-point.md) - Role Details: GND return access pad, 1.25mm - Package: SMD - Role: Test Point **Pins:** - P1 ### TP_GND3 — [1.25mm SMD Test Point](https://www.flux.ai/jharwinbarrozo/1p25mm-smd-test-point.md) - Package: SMD - Role: Test Point - Role Details: GND return access pad, 1.25mm **Pins:** - P1 ### TP_GND4 — [1.25mm SMD Test Point](https://www.flux.ai/jharwinbarrozo/1p25mm-smd-test-point.md) - Role: Test Point - Package: SMD - Role Details: GND stitch / probe point for routing and debug **Pins:** - P1 ### TP_GND5 — [1.25mm SMD Test Point](https://www.flux.ai/jharwinbarrozo/1p25mm-smd-test-point.md) - Role Details: GND stitch / probe point for routing and debug - Role: Test Point - Package: SMD **Pins:** - P1 ### TP_GND6 — [1.25mm SMD Test Point](https://www.flux.ai/jharwinbarrozo/1p25mm-smd-test-point.md) - Role Details: GND stitch / probe point for routing and debug - Role: Test Point - Package: SMD **Pins:** - P1 ### TP_GND7 — [1.25mm SMD Test Point](https://www.flux.ai/jharwinbarrozo/1p25mm-smd-test-point.md) - Role Details: GND stitch / probe point for routing and debug - Role: Test Point - Package: SMD **Pins:** - P1 ### TP_VBAT1 — [1.25mm SMD Test Point](https://www.flux.ai/jharwinbarrozo/1p25mm-smd-test-point.md) - Role: Test Point - Package: SMD - Role Details: VBAT routing fanout pad, 1.25mm **Pins:** - P1 ### TP_VBAT2 — [1.25mm SMD Test Point](https://www.flux.ai/jharwinbarrozo/1p25mm-smd-test-point.md) - Role Details: VBAT routing fanout pad, 1.25mm - Role: Test Point - Package: SMD **Pins:** - P1 ### TP_VBAT3 — [1.25mm SMD Test Point](https://www.flux.ai/jharwinbarrozo/1p25mm-smd-test-point.md) - Package: SMD - Role Details: VBAT routing fanout pad, 1.25mm - Role: Test Point **Pins:** - P1 ### TP_VBAT4 — [1.25mm SMD Test Point](https://www.flux.ai/jharwinbarrozo/1p25mm-smd-test-point.md) - Role: Test Point - Role Details: VBAT probe point for routing and debug - Package: SMD **Pins:** - P1 ### TP_VBAT5 — [1.25mm SMD Test Point](https://www.flux.ai/jharwinbarrozo/1p25mm-smd-test-point.md) - Role: Test Point - Role Details: VBAT probe point for routing and debug - Package: SMD **Pins:** - P1 ### U1 — [SIM800C](https://www.flux.ai/lcsc/sim800c.md) - JLCPCB Part Class: Extended Part - Part Type: 2G/3G/4G/5G Modules - Role: Modem - Manufacturer Part Number: SIM800C - Package or Case Code: GSM-SMD_42P-L17.6-W15.7-P1.10-TL - LCSC Part Number: C2981431 - Role Details: SIM800C SMS communications over UART - Manufacturer Name: SIMCOM - Package: GSM-SMD_42P-L17.6-W15.7-P1.10-TL **Pins:** - ADC [pin 38] - BT_ANT [pin 20] - GND [pin 21] - GND [pin 36] - GND [pin 33] - GND [pin 27] - GND [pin 31] - GND [pin 19] - GND [pin 30] - GND [pin 13] - GND [pin 37] - GND [pin 8] - GSM_ANT [pin 32] - MICN [pin 10] - MICP [pin 9] - NETLIGHT [pin 41] - PWRKEY [pin 39] - RF_SYNC [pin 29] - SIM_CLK [pin 16] - SIM_DATA [pin 15] - SIM_DET [pin 14] - SIM_RST [pin 17] - SIM_VDD [pin 18] - SPKN [pin 12] - SPKP [pin 11] - STATUS [pin 42] - UART1_CTS [pin 4] - UART1_DCD [pin 5] - UART1_DTR [pin 6] - UART1_RI [pin 7] - UART1_RTS [pin 3] - UART1_RXD [pin 2] - UART1_TXD [pin 1] - UART2_RXD [pin 23] - UART2_TXD [pin 22] - USB_DN [pin 26] - USB_DP [pin 25] - USB_VBUS [pin 24] - VBAT [pin 34] - VBAT [pin 35] - VDD_EXT [pin 40] - VRTC [pin 28] ### U2 — [STM32F423RHT6](https://www.flux.ai/vasy_skral/stm32f423rht6.md) - Manufacturer Part Number: STM32F423RHT6 - Datasheet URL: https://www.st.com/content/ccc/resource/technical/document/datasheet/group3/b9/bf/95/d3/b2/22/42/f0/DM00282247/files/DM00282247.pdf/jcr:content/translations/en.DM00282247.pdf - Part Type: Microcontroller - Role: MCU - Package: LQFP-64_10x10mm_P0.5mm - Role Details: Controls MSR read, encrypts records, authenticates commands, drives SIM800C UART - Manufacturer Name: STMicroelectronics **Pins:** - BOOT0 [pin 60] - NRST [pin 7] - PA0 [pin 14] - PA1 [pin 15] - PA10 [pin 43] - PA11 [pin 44] - PA12 [pin 45] - PA13 [pin 46] - PA14 [pin 49] - PA15 [pin 50] - PA2 [pin 16] - PA3 [pin 17] - PA4 [pin 20] - PA5 [pin 21] - PA6 [pin 22] - PA7 [pin 23] - PA8 [pin 41] - PA9 [pin 42] - PB0 [pin 26] - PB1 [pin 27] - PB10 [pin 29] - PB12 [pin 33] - PB13 [pin 34] - PB14 [pin 35] - PB15 [pin 36] - PB2 [pin 28] - PB3 [pin 55] - PB4 [pin 56] - PB5 [pin 57] - PB6 [pin 58] - PB7 [pin 59] - PB8 [pin 61] - PB9 [pin 62] - PC0 [pin 8] - PC1 [pin 9] - PC10 [pin 51] - PC11 [pin 52] - PC12 [pin 53] - PC13 [pin 2] - PC14 [pin 3] - PC15 [pin 4] - PC2 [pin 10] - PC3 [pin 11] - PC4 [pin 24] - PC5 [pin 25] - PC6 [pin 37] - PC7 [pin 38] - PC8 [pin 39] - PC9 [pin 40] - PD2 [pin 54] - PH0 [pin 5] - PH1 [pin 6] - VBAT [pin 1] - VCAP_1 [pin 30] - VDD [pin 64] - VDD [pin 19] - VDD [pin 32] - VDD [pin 48] - VDDA [pin 13] - VSS [pin 47] - VSS [pin 18] - VSS [pin 63] - VSS [pin 31] - VSSA [pin 12] ### U3 — [ATECC608A-MAHDA-S](https://www.flux.ai/lcsc/atecc608a-mahda-s.md) - Manufacturer Part Number: ATECC608A-MAHDA-S - JLCPCB Part Class: Extended Part - Role: Secure Element - Package or Case Code: UDFN-8_L3.0-W2.0-P0.50-BL - LCSC Part Number: C616908 - Role Details: Stores device secrets; supports authenticated command workflow - Package: UDFN-8_L3.0-W2.0-P0.50-BL - Manufacturer Name: Microchip **Pins:** - EXP [pin 9] - GND [pin 4] - NC [pin 2] - NC [pin 3] - NC [pin 7] - NC [pin 1] - SCL [pin 6] - SDA [pin 5] - VCC [pin 8] *The full schematic, PCB layout, bill of materials, and interactive design are available at [https://www.flux.ai/ov2319/sophisticated-beige-gadget-copter](https://www.flux.ai/ov2319/sophisticated-beige-gadget-copter).* --- *Generated from [https://www.flux.ai/ov2319/sophisticated-beige-gadget-copter](https://www.flux.ai/ov2319/sophisticated-beige-gadget-copter)*