# Student Energy Meter ## Description Single-phase student energy meter using ATM90E26 metering IC, STM32F103 MCU, OLED display, USB-UART communication, transformer voltage sensing, and SCT013 current sensing. Designed for a 2-layer PCB within 150 mm x 150 mm and a BOM target below 50 EUR. ## Project Details - **Owner:** lenka123 - **Created:** 4/7/2026 - **Last Updated:** 4/8/2026 - **Visibility:** Public ## Key Components ### J1 — [PJ-002AH-SMT-TR](https://www.flux.ai/carlosyungo/pj-002ah-smt-tr~5w.md) - Manufacturer Part Number: PJ-002AH-SMT-TR - Manufacturer Name: Texas Instruments Inc. - Package: SMT - Role: Voltage Sense Connector - Role Details: Connector for transformer secondary feeding the ATM90E26 voltage sensing network **Pins:** - ~ [pin 1B] - ~ [pin 2] - ~ [pin 3] - ~ [pin 1A] ### J2 — [SJ-3523-SMT-TR](https://www.flux.ai/vasy_skral/sj-3523-smt-tr~6n4.md) - Package: SMT - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Name: CUI Devices - Role: Current Sense Connector - Part Type: Connector - Datasheet URL: https://www.cuidevices.com/product/resource/sj-352x-smt.pdf - Manufacturer Part Number: SJ-3523-SMT-TR - Role Details: Stereo jack used to receive SCT013 current transformer output **Pins:** - R [pin R] - S [pin S] - T [pin T] ### J3 — [USB4105-GF-A](https://www.flux.ai/adrian95/usb4105-gf-a~im9.md) - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Part Number: USB4105-GF-A - Part Type: USB C - Datasheet URL: https://mm.digikey.com/Volume0/opasdata/d220001/medias/docus/5492/USB4105.pdf - Role: USB Connector - Role Details: USB-C sink connector carrying VBUS, GND, D+, D-, and CC detection - Manufacturer Name: GCT - Manufacturer Name: GCT - Package: USB-C Receptacle **Pins:** - CC1 [pin A5] - CC2 [pin B5] - DN1 [pin A7] - DN2 [pin B7] - DP1 [pin A6] - DP2 [pin B6] - GND [pin A1_B12] - GND__1 [pin B1_A12] - SBU1 [pin A8] - SBU2 [pin B8] - SHELL_GND [pin SH1] - SHELL_GND__1 [pin SH2] - SHELL_GND__2 [pin SH3] - SHELL_GND__3 [pin SH4] - VBUS [pin A4_B9] - VBUS__1 [pin B4_A9] ### J4 — [640456-6](https://www.flux.ai/adrian95/640456-6~oy5.md) - Manufacturer Name: TE Connectivity AMP Connectors - Package: 2.54mm TH Header - Part Type: Connector - Manufacturer Part Number: 640456-6 - Package or Case Code: SHDR6W66P0X254_1X6_1524X572X1003P - License: https://creativecommons.org/licenses/by/4.0/ - Datasheet URL: https://www.te.com/usa-en/product-640456-6.datasheet.pdf - Role: Debug Header - Role Details: Standard 1x6 SWD header for SWDIO, SWCLK, NRST, 3V3, GND, and SWO or UART auxiliary **Pins:** - 1 [pin 1] - 2 [pin 2] - 3 [pin 3] - 4 [pin 4] - 5 [pin 5] - 6 [pin 6] ### LED1 — [LTST-C190GKT](https://www.flux.ai/adrian95/ltst-c190gkt~hjc.md) - Role Details: 3.3V power/status indicator - Datasheet URL: https://media.digikey.com/pdf/Data%20Sheets/Lite-On%20PDFs/LTST-C190AKT.pdf - Package: 0603 - Manufacturer Name: Lite-On Inc. - Part Type: LED - Manufacturer Part Number: LTST-C190GKT - License: https://creativecommons.org/licenses/by/4.0/ - Role: Indicator LED **Pins:** - A [pin 2] - K [pin 1] ### SW1 — [TL3301AF160QG](https://www.flux.ai/jecstronic/tl3301af160qg~bdf.md) - Role Details: Momentary reset pushbutton for NRST line - Part Type: Switch - Manufacturer Name: E-Switch - Datasheet URL: https://datasheet.lcsc.com/lcsc/1810101632_E-Switch-TL3301AF160QG_C273519.pdf - Manufacturer Part Number: TL3301AF160QG - Package: SMD 6x6mm - Role: Reset Switch **Pins:** - 1 - 2 - 3 - 4 ### U1 — [ATM90E26-YU-B](https://www.flux.ai/jecstronic/atm90e26-yu-b~op5.md) - Manufacturer Part Number: ATM90E26-YU-B - Role: Metering IC - Datasheet URL: https://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-46002-SE-M90E26-Datasheet.pdf - Package: TQFP-28 - License: https://creativecommons.org/licenses/by/4.0/ - Part Type: Power Management - Manufacturer Name: Microchip Technology - Role Details: Single-phase metering front end with SPI interface, pulse outputs, zero-crossing, and interrupt support **Pins:** - ~CS [pin 24] - ~RESET [pin 4] - AGND_1 [pin 6] - AGND_2 [pin 14] - AVDD [pin 5] - CF1 [pin 18] - CF2 [pin 19] - DGND [pin 2] - DVDD [pin 3] - I1N [pin 11] - I1P [pin 10] - I2N [pin 8] - I2P [pin 7] - IRQ [pin 20] - MMD0 [pin 28] - MMD1 [pin 1] - OSCI [pin 22] - OSCO [pin 23] - RESV_LOW [pin 9] - SCLK [pin 25] - SDI/URX [pin 27] - SDO/UTX [pin 26] - USEL [pin 12] - VN [pin 15] - VP [pin 16] - VREF [pin 13] - WARNOUT [pin 17] - ZX [pin 21] ### U2 — [STM32F103C8T6](https://www.flux.ai/jharwinbarrozo/stm32f103c8t6~qe2.md) - Datasheet URL: https://datasheet.lcsc.com/lcsc/1811151642_STMicroelectronics-STM32F103C8T6_C8734.pdf - Part Type: Microcontroller - Role Details: Runs metering firmware, reads ATM90E26 over SPI, drives OLED over I2C, and communicates through UART and SWD - Package: LQFP-48 - Manufacturer Name: STMicroelectronics - Manufacturer Part Number: STM32F103C8T6 - Role: MCU **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 48] - VDD [pin 24] - VDD [pin 36] - VDDA [pin 9] - VSS [pin 47] - VSS [pin 23] - VSS [pin 35] - VSSA [pin 8] ### U3 — [CH340C](https://www.flux.ai/vasy_skral/ch340c~xfo.md) - Role: USB-UART Interface - Datasheet URL: https://datasheet.lcsc.com/szlcsc/Jiangsu-Qin-Heng-CH340C_C84681.pdf - Package: SOP-16 - Part Type: Integrated Circuit - Manufacturer Name: Wah - Manufacturer Part Number: CH340C - Role Details: Bridges USB 2.0 data to STM32 UART for console and data logging **Pins:** - ~CTS [pin 9] - ~DCD [pin 12] - ~DSR [pin 10] - ~DTR [pin 13] - ~RI [pin 11] - ~RTS [pin 14] - GND [pin 1] - NC [pin 7] - NC [pin 8] - R232 [pin 15] - RXD [pin 3] - TXD [pin 2] - UD- [pin 6] - UD+ [pin 5] - V3 [pin 4] - VCC [pin 16] ### U4 — [AP2112K-3.3TRG1](https://www.flux.ai/adrian95/ap2112k-33trg1~zlq.md) - Datasheet URL: Diodes Incorporated - Role: Regulator - Manufacturer Part Number: AP2112K-3.3TRG1 - License: https://creativecommons.org/licenses/by/4.0/ - Part Type: Integrated Circuit - Package: SOT-25 - Manufacturer Name: https://www.diodes.com/assets/Datasheets/AP2112.pdf - Role Details: Main 3.3V LDO from 5V input rail **Pins:** - EN [pin 3] - GND [pin 2] - NC [pin 4] - VIN [pin 1] - VOUT [pin 5] ### X1 — [XSMEELNANF-8.192MHZ](https://www.flux.ai/lcsc/xsmeelnanf-8p192mhz~6f3x.md) - Role Details: 8.192 MHz crystal for ATM90E26 metering clock - Package or Case Code: OSC-SMD_2P-L5.0-W3.2 - Datasheet URL: https://storage.googleapis.com/graviton-electric-symbols/document_assets/lcsc/1811052123_TAITIEN-Elec-XSMEELNANF-8-192MHZ_C242222.pdf - LCSC Part Number: C242222 - Part Type: Crystals - Product Info Url: https://lcsc.com/product-detail/Others_TAITIEN-Elec-XSMEELNANF-8-192MHZ_C242222.html - JLCPCB Part Class: Extended Part - Manufacturer Name: TAITIEN(泰艺电子) - Manufacturer Part Number: XSMEELNANF-8.192MHZ - Role: Clock - Package: OSC-SMD_2P-L5.0-W3.2 **Pins:** - OSC1 [pin 1] - OSC2 [pin 2] *The full schematic, PCB layout, bill of materials, and interactive design are available at [https://www.flux.ai/lenka123/student-energy-meter~sn](https://www.flux.ai/lenka123/student-energy-meter~sn).* --- *Generated from [https://www.flux.ai/lenka123/student-energy-meter~sn](https://www.flux.ai/lenka123/student-energy-meter~sn)*