# pcb making 2344 ## Description Nextion HMI & Thermal Printer UART Integration with Enhanced microSD SPI Interface, ESD Protection, and LP3982-Regulated 3.3V Power Rail ## Project Details - **Owner:** koertsunay - **Created:** 10/30/2025 - **Last Updated:** 10/30/2025 - **Visibility:** Public - **UART1 Header Pinout:** 1: +5V (U3:VCC), 2: GND (GND), 3: TX1 (U3:PE1), 4: RX1 (U3:PE0) - **Allow Substitutes:** Yes - **System Architecture:** graph LR MCU[ATmega2560] JN[J_NEXTION] JP[J_PRINTER] SD[microSD Socket] P5(+5V) GND(GND) U2[LP3982ILD-3.3 LDO] P33(+3.3V) TP3[TP_3V3] P5 --> MCU GND --> MCU JN --> MCU JP --> MCU SD --> MCU P5 --> SD GND --> SD P5 --> U2 U2 --> P33 P33 --> SD P33 --> TP3 - **Role:** Power Conversion - **Part Type:** Power Management - **Designators:** J24V_IN, D1, U1, U2, TP_V24, TP_5V, TP_GND, TP_3V3 - **Domain:** Industrial/Manufacturing - **Role Details:** Converts input 24V (J24V_IN) down to 5V via Buck Converter (U1) and optionally to 3.3V via LDO (U2); Over-voltage protection via TVS diode (D1); Filtering/decoupling provided by various capacitors and inductor. - **ERC_Warnings:** None – All warnings and errors resolved. - **ERC_Warnings:** Warning: Missing decoupling capacitor on U3 AVCC pin; Error: U3 RESET pin missing pull-up resistor. - **Operating Voltage:** 24V - **ERC_decoupling_caps_review:** Complete – AVCC decoupling capacitors present, location verified, no ERC warnings. - **ERC_pull_up_pull_down_review:** Complete – RESET pull-up resistor present and correct, no ERC warnings. - **Output Voltage(s):** +5V, +3.3V (optional) - **ICSP Header Pinout:** 1: MOSI (U3:PB3), 2: +5V (U3:VCC), 3: MISO (U3:PB4), 4: GND (GND), 5: SCK (U3:PB5), 6: RESET (U3:~RESET) - **JLCPCB Part Class:** Extended Part - **PCB Stackup Layers:** 2 - **UART2 Header Pinout:** 1: +5V (U3:VCC), 2: GND (GND), 3: TX2 (U3:PH1), 4: RX2 (U3:PH0) - **Power Requirements:** Mains (implied by 24V input) - **ERC Summary:** ERC review for AVCC decoupling and RESET pull-up shows no remaining warnings or errors. ICSP header mapping confirmed correct. Implementation plan success criteria fully satisfied. ## Key Components ### D1 — [SMCJ33A-13-F](https://www.flux.ai/lcsc/smcj33a-13-f.md) - Datasheet URL: https://storage.googleapis.com/graviton-electric-symbols/document_assets/lcsc/2304140030_Diodes-Incorporated-SMCJ33A-13-F_C135162.pdf - LCSC Part Number: C135162 - Role Details: TVS diode for over-voltage protection on 24V input, cathode to V24, anode to GND - Package or Case Code: SMC_L6.9-W5.9-LS7.9-R-RD - Role: Protection - JLCPCB Part Class: Extended Part - Part Type: TVS - Manufacturer Name: DIODES(美台) - Manufacturer Part Number: SMCJ33A-13-F - Product Info Url: https://lcsc.com/product-detail/TVS_Diodes-Incorporated-SMCJ33A-13-F_C135162.html **Pins:** - 1 [pin 1] - 2 [pin 2] ### J_DI — [1546551-5](https://www.flux.ai/adrian95/1546551-5.md) - Manufacturer Part Number: 1546551-5 - Part Type: Connector - License: https://creativecommons.org/licenses/by/4.0/ - Datasheet URL: https://www.te.com/usa-en/product-1546551-5.datasheet.pdf - Manufacturer Name: TE Connectivity AMP Connectors - Role Details: Field DI connector, 5-pin 3.5 mm terminal block (pins: +5V, DI_1..DI_4) - Role: Connector **Pins:** - 1 [pin 1] - 2 [pin 2] - 3 [pin 3] - 4 [pin 4] - 5 [pin 5] ### J_NEXTION — [61300411121](https://www.flux.ai/adrian95/61300411121.md) - Role: Connector - Role Details: UART1 header: +5V, GND, TX1, RX1 - Package or Case Code: HDRV4W95P0X254_1X4_1016X254X854P - Manufacturer Part Number: 61300411121 - Part Type: Connector - License: https://creativecommons.org/licenses/by/4.0/ - Datasheet URL: https://www.we-online.com/components/products/datasheet/61300411121.pdf - Manufacturer Name: Wurth Elektronik **Pins:** - 1 [pin 1] - 2 [pin 2] - 3 [pin 3] - 4 [pin 4] ### J_PRINTER — [61300411121](https://www.flux.ai/adrian95/61300411121.md) - Role: Connector - License: https://creativecommons.org/licenses/by/4.0/ - Part Type: Connector - Manufacturer Part Number: 61300411121 - Package or Case Code: HDRV4W95P0X254_1X4_1016X254X854P - Manufacturer Name: Wurth Elektronik - Datasheet URL: https://www.we-online.com/components/products/datasheet/61300411121.pdf - Role Details: UART2 header: +5V, GND, TX2, RX2 **Pins:** - 1 [pin 1] - 2 [pin 2] - 3 [pin 3] - 4 [pin 4] ### J_SDCARD — [MEM2085](https://www.flux.ai/digitalninjae/mem2085.md) - Manufacturer Name: GCT - Datasheet URL: https://gct.co/files/drawings/mem2085.pdf - Part Type: SD Card - Manufacturer Part Number: MEM2085-00-115-00-A - Role: Connector},{ - Role Details: Push-push microSD card socket with integrated Card Detect pin **Pins:** - CD - GND 1 [pin G1] - GND 10 [pin G10] - GND 2 [pin G2] - GND 3 [pin G3] - GND 4 [pin G4] - GND 5 [pin G5] - GND 6 [pin G6] - GND 7 [pin G7] - GND 8 [pin G8] - GND 9 [pin G9] - P1 [pin DAT2] - P2 [pin CD/DAT3] - P3 [pin CMD] - P4 [pin VDD] - P5 [pin CLK] - P6 [pin VSS] - P7 [pin DAT0] - P8 [pin DAT1] ### J24V_IN — [282837-2](https://www.flux.ai/vasy_skral/282837-2.md) - Manufacturer Part Number: 282837-2 - Role: Connector - Part Type: Connector - Role Details: 24V input terminal block, via 2-pin 5.08 mm terminal, connects V24 and GND - Manufacturer Name: TE Connectivity AMP Connectors - Datasheet URL: https://www.te.com/commerce/DocumentDelivery/DDEController?Action=srchrtrv&DocNm=282837&DocType=Customer+Drawing&DocLang=English **Pins:** - 1 [pin 1] - 2 [pin 2] ### JICSP — [M2557V-2x3-N0](https://www.flux.ai/lcsc/m2557v-2x3-n0.md) - Package or Case Code: CONN-TH_M2557V-2X3-N0 - JLCPCB Part Class: Extended Part - Manufacturer Part Number: M2557V-2x3-N0 - Part Type: Wire To Board / Wire To Wire Connector - Role Details: ICSP 2×3 header for programming U3 - Role: Connector - Manufacturer Name: XFCN(台湾兴飞) - LCSC Part Number: C2832263 **Pins:** - 1 [pin 1] - 2 [pin 2] - 3 [pin 3] - 4 [pin 4] - 5 [pin 5] - 6 [pin 6] ### P1 — [Generic Resistor](https://www.flux.ai/jharwinbarrozo/generic-resistor.md) - Role: Pull Up / Down - Part Type: Resistor - Role Details: Pull-up for part U3, pin RESET - Package: SMD_0603_1608Metric - Resistance: 500Ω **Pins:** - P1 [pin 1] - P2 [pin 2] ### P1 — [Generic Resistor](https://www.flux.ai/jharwinbarrozo/generic-resistor.md) - Part Type: Resistor - Role: Pull Up / Down - Role Details: Pull-up for part U3, pin RESET - Package: SMD_0603_1608Metric - Resistance: 10kΩ **Pins:** - P1 [pin 1] - P2 [pin 2] ### SW1 — [TLSA040JLFS](https://www.flux.ai/vasy_skral/tlsa040jlfs.md) - Manufacturer Name: C&K - Role Details: Manual reset pushbutton connecting RESET to GND - Datasheet URL: https://www.mouser.sk/datasheet/2/60/tls-1846606.pdf - Role: Switch - Part Type: Switch - Manufacturer Part Number: TLSA040JLFS **Pins:** - P1 [pin 1] - P2 [pin 2] ### U1 — [TPS56339DDCT](https://www.flux.ai/lcsc/tps56339ddct.md) - LCSC Part Number: C2071585 - Role: Power Conversion - Manufacturer Part Number: TPS56339DDCT - Part Type: DC-DC Converters - Package or Case Code: TSOT-23-6_L2.9-W1.6-P0.95-LS2.8-BR - Role Details: Buck converter for 24V to 5V power rail - JLCPCB Part Class: Extended Part - Manufacturer Name: TI(德州仪器) **Pins:** - BOOT [pin 6] - EN [pin 5] - FB [pin 4] - GND [pin 1] - SW [pin 2] - VIN [pin 3] ### U2 — [LP3982ILD-3.3](https://www.flux.ai/adrian95/lp3982ild-33.md) - Manufacturer Part Number: LP3982ILD-3.3 - Datasheet URL: https://www.ti.com/product/LP3982?HQS=TI-null-null-octopart-df-pf-null-wwe#product-details##description - Role: Power Conversion - License: https://creativecommons.org/licenses/by/4.0/ - Part Type: Integrated Circuit - Role Details: LDO converting +5V to +3.3V rail - Manufacturer Name: Texas Instruments **Pins:** - CC [pin 6] - EP [pin 9] - FAULT [pin 8] - GND [pin 3] - IN [pin 2] - NC [pin 5] - OUT [pin 4] - OUT [pin 1] - SHDN [pin 7] ### U2 — [LP3982ILD-3.3](https://www.flux.ai/adrian95/lp3982ild-33.md) - Datasheet URL: https://www.ti.com/product/LP3982?HQS=TI-null-null-octopart-df-pf-null-wwe#product-details##description - Manufacturer Part Number: LP3982ILD-3.3 - Role: Power Conversion - Manufacturer Name: Texas Instruments - License: https://creativecommons.org/licenses/by/4.0/ - Role Details: LDO converting +5V to +3.3V rail - Part Type: Integrated Circuit **Pins:** - CC [pin 6] - EP [pin 9] - FAULT [pin 8] - GND [pin 3] - IN [pin 2] - NC [pin 5] - OUT [pin 4] - OUT [pin 1] - SHDN [pin 7] ### U3 — [ATMEGA2560-16AU](https://www.flux.ai/vasy_skral/atmega2560-16au.md) - Role: Microcontroller - Datasheet URL: https://ww1.microchip.com/downloads/en/DeviceDoc/ATmega640-1280-1281-2560-2561-Datasheet-DS40002211A.pdf - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Part Number: ATMEGA2560-16AU - Manufacturer Name: Microchip - Part Type: Microcontroller - Role Details: Main MCU **Pins:** - ~RESET [pin 30] - AREF [pin 98] - AVCC [pin 100] - GND [pin 99] - GND [pin 32] - GND [pin 62] - GND [pin 81] - GND [pin 11] - PA0 [pin 78] - PA1 [pin 77] - PA2 [pin 76] - PA3 [pin 75] - PA4 [pin 74] - PA5 [pin 73] - PA6 [pin 72] - PA7 [pin 71] - PB0 [pin 19] - PB1 [pin 20] - PB2 [pin 21] - PB3 [pin 22] - PB4 [pin 23] - PB5 [pin 24] - PB6 [pin 25] - PB7 [pin 26] - PC0 [pin 53] - PC1 [pin 54] - PC2 [pin 55] - PC3 [pin 56] - PC4 [pin 57] - PC5 [pin 58] - PC6 [pin 59] - PC7 [pin 60] - PD0 [pin 43] - PD1 [pin 44] - PD2 [pin 45] - PD3 [pin 46] - PD4 [pin 47] - PD5 [pin 48] - PD6 [pin 49] - PD7 [pin 50] - PE0 [pin 2] - PE1 [pin 3] - PE2 [pin 4] - PE3 [pin 5] - PE4 [pin 6] - PE5 [pin 7] - PE6 [pin 8] - PE7 [pin 9] - PF0 [pin 97] - PF1 [pin 96] - PF2 [pin 95] - PF3 [pin 94] - PF4 [pin 93] - PF5 [pin 92] - PF6 [pin 91] - PF7 [pin 90] - PG0 [pin 51] - PG1 [pin 52] - PG2 [pin 70] - PG3 [pin 28] - PG4 [pin 29] - PG5 [pin 1] - PH0 [pin 12] - PH1 [pin 13] - PH2 [pin 14] - PH3 [pin 15] - PH4 [pin 16] - PH5 [pin 17] - PH6 [pin 18] - PH7 [pin 27] - PJ0 [pin 63] - PJ1 [pin 64] - PJ2 [pin 65] - PJ3 [pin 66] - PJ4 [pin 67] - PJ5 [pin 68] - PJ6 [pin 69] - PJ7 [pin 79] - PK0 [pin 89] - PK1 [pin 88] - PK2 [pin 87] - PK3 [pin 86] - PK4 [pin 85] - PK5 [pin 84] - PK6 [pin 83] - PK7 [pin 82] - PL0 [pin 35] - PL1 [pin 36] - PL2 [pin 37] - PL3 [pin 38] - PL4 [pin 39] - PL5 [pin 40] - PL6 [pin 41] - PL7 [pin 42] - VCC [pin 10] - VCC [pin 80] - VCC [pin 31] - VCC [pin 61] - XTAL1 [pin 34] - XTAL2 [pin 33] ### U4 — [ESD224DQA](https://www.flux.ai/kicad-part-library/esd224dqa.md) - Package or Case Code: Diodes_UDFN-10_1.0x2.5mm_P0.5mm - Manufacturer Name: Texas Instruments Inc. - Manufacturer Part Number: ESD224DQA - Datasheet URL: https://www.ti.com/lit/ds/symlink/esd224.pdf - Role Details: ESD protection for SPI lines (SCK, MOSI, MISO, SD_CS) - Role: Protection **Pins:** - ~ [pin 7] - ~ [pin 2] - ~ [pin 4] - ~ [pin 5] - ~ [pin 6] - ~ [pin 1] - ~ [pin 9] - ~ [pin 10] - VSS [pin 3] - VSS [pin 8] ### Y1 — [NX5032GA-16MHZ-STD-CSU-2](https://www.flux.ai/lcsc/nx5032ga-16mhz-std-csu-2.md) - LCSC Part Number: C485370 - Role Details: 16 MHz crystal for U3 clock - Manufacturer Name: NDK - JLCPCB Part Class: Extended Part - Manufacturer Part Number: NX5032GA-16MHZ-STD-CSU-2 - Datasheet URL: https://storage.googleapis.com/graviton-electric-symbols/document_assets/lcsc/2304140030_NDK-NX5032GA-16MHZ-STD-CSU-2_C485370.pdf - Product Info Url: https://lcsc.com/product-detail/SMD-Crystal-Resonators_NDK-NX5032GA-16MHZ-STD-CSU-2_C485370.html - Role: Oscillator - Package or Case Code: CRYSTAL-SMD_L5.0-W3.2-1 - Part Type: Crystals **Pins:** - 1 [pin 1] - 2 [pin 2] *The full schematic, PCB layout, bill of materials, and interactive design are available at [https://www.flux.ai/koertsunay/pcb-making-2344](https://www.flux.ai/koertsunay/pcb-making-2344).* --- *Generated from [https://www.flux.ai/koertsunay/pcb-making-2344](https://www.flux.ai/koertsunay/pcb-making-2344)*