# PIC16F877A HX711 Load Cell Interface ## Description PIC16F877A-based load-cell measurement system using an HX711 24-bit ADC, 4 MHz crystal clock, load-cell connector, ICSP programming header, regulated 5V input, and low-noise PCB layout for internship deliverables. ## Project Details - **Owner:** abeetpaul - **Created:** 3/31/2026 - **Last Updated:** 4/1/2026 - **Visibility:** Public ## Key Components ### J1 — [1-2834021-4](https://www.flux.ai/adrian95/1-2834021-4.md) - Manufacturer Part Number: 1-2834021-4 - Datasheet URL: https://www.te.com/usa-en/product-1-2834021-4.datasheet.pdf - Part Type: Connector - License: https://creativecommons.org/licenses/by/4.0/ - Role: Load Cell Connector - Manufacturer Name: TE Connectivity AMP Connectors - Role Details: 4-wire connector for E+, E-, A+, A- load cell cable termination - Package: THT 4-pos 2.5mm **Pins:** - 1 [pin 1] - 2 [pin 2] - 3 [pin 3] - 4 [pin 4] ### J2 — [Pin Header 01x06 2.54mm PROGRAMMING CONNECTOR](https://www.flux.ai/zalak201285/pin-header-01x06-2p54mm-programming-connector.md) - Role: ICSP Header - Part Type: Connector - License: https://creativecommons.org/licenses/by/4.0/ - Role Details: PIC in-circuit serial programming header carrying MCLR/VPP, +5V, GND, PGD, and PGC - Package: THT 1x6 2.54mm **Pins:** - JTCK [pin 2] - JTDI [pin 1] - JTDO [pin 3] - JTMS [pin 4] - NJTRST [pin 5] - RESET [pin 6] ### J3 — [KF128-5.08-2P-AA](https://www.flux.ai/lcsc/kf128-5p08-2p-aa.md) - Part Type: Screw terminal - Role Details: External 5V DC power input connector for bench supply or adapter - Manufacturer Part Number: KF128-5.08-2P-AA - Manufacturer Name: KEFA(科发) - Product Info Url: https://lcsc.com/product-detail/New-Quadratic-Unclassified-Data_Cixi-Kefa-Elec-KF128-5-08-2P_C474952.html - Connector Pitch: 5.08mm - Connector Positions: 2 - Connector Type: Screw terminal - LCSC Part Number: C474952 - Role: Power Input - Operating Temperature: -40℃~+105℃ - JLCPCB Part Class: Extended Part - Package or Case Code: CONN-TH_P5.08_KF128-5.08-2P - Current Rating: 24A - Connector Rows: 1 - Datasheet URL: https://storage.googleapis.com/graviton-electric-symbols/document_assets/lcsc/2408211511_Cixi-Kefa-Elec-KF128-5-08-2P-AA_C474952.pdf - Package: THT 2-pos 5.08mm - Connector Gender: Female **Pins:** - 1 [pin 1] - 2 [pin 2] ### LED1 — [WP937AD/EGW](https://www.flux.ai/jecstronic/wp937adegw.md) - Role Details: Green LED showing presence of the 5V rail - Manufacturer Name: Kingbright - Role: Power Indicator - Part Type: LED - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Part Number: WP937AD/EGW - Datasheet URL: https://www.kingbrightusa.com/images/catalog/SPEC/WP937AD-EGW.pdf - Package: THT 3mm **Pins:** - 1 [pin 1] - 2 [pin 2] ### S1 — [B3F-1000](https://www.flux.ai/adrian95/b3f-1000.md) - Manufacturer Name: Omron Electronics Inc-EMC Div - Role: Reset Switch - Role Details: Momentary normally-open pushbutton to pull MCLR low for manual reset - Package: THT Tactile - License: https://creativecommons.org/licenses/by/4.0/ - Datasheet URL: https://omronfs.omron.com/en_US/ecb/products/pdf/en-b3f.pdf - Part Type: Switch - Manufacturer Part Number: B3F-1000 **Pins:** - 1 [pin 1] - 2 [pin 2] - 3 [pin 3] - 4 [pin 4] ### U1 — [PIC16F877A-I/P](https://www.flux.ai/adrian95/pic16f877a-ip.md) - Package: PDIP-40 - License: https://creativecommons.org/licenses/by/4.0/ - Datasheet URL: https://ww1.microchip.com/downloads/en/DeviceDoc/39582C.pdf - Role: Microcontroller - Manufacturer Name: Microchip Technology - Part Type: Microcontroller - Role Details: Main controller running at 4 MHz; reads HX711 with DOUT on RB0 and SCK on RB1; provides ICSP programming access - Manufacturer Part Number: PIC16F877A-I/P **Pins:** - ~MCLR~/VPP [pin 1] - OSC1/CLKI [pin 13] - OSC2/CLKO [pin 14] - RA0/AN0 [pin 2] - RA1/AN1 [pin 3] - RA2/AN2/VREF-/CVREF [pin 4] - RA3/AN3/VREF+ [pin 5] - RA4/T0CKI/C1OUT [pin 6] - RA5/AN4/~SS~/C2OUT [pin 7] - RB0/INT [pin 33] - RB1 [pin 34] - RB2 [pin 35] - RB3/PGM [pin 36] - RB4 [pin 37] - RB5 [pin 38] - RB6/PGC [pin 39] - RB7/PGD [pin 40] - RC0/T1OSO/T1CKI [pin 15] - RC1/T1OSI/CCP2 [pin 16] - RC2/CCP1 [pin 17] - RC3/SCK/SCL [pin 18] - RC4/SDI/SDA [pin 23] - RC5/SDO [pin 24] - RC6/TX/CK [pin 25] - RC7/RX/DT [pin 26] - RD0/PSP0 [pin 19] - RD1/PSP1 [pin 20] - RD2/PSP2 [pin 21] - RD3/PSP3 [pin 22] - RD4/PSP4 [pin 27] - RD5/PSP5 [pin 28] - RD6/PSP6 [pin 29] - RD7/PSP7 [pin 30] - RE0/~RD~/AN5 [pin 8] - RE1/~WR~/AN6 [pin 9] - RE2/~CS~/AN7 [pin 10] - VDD_1 [pin 11] - VDD_2 [pin 32] - VSS_1 [pin 12] - VSS_2 [pin 31] ### U2 — [HX711](https://www.flux.ai/kicad-part-library/hx711.md) - Package: SOP-16 - Package or Case Code: SOP-16_3.9x9.9mm_P1.27mm - Datasheet URL: https://web.archive.org/web/20220615044707/https://akizukidenshi.com/download/ds/avia/hx711.pdf - Manufacturer Part Number: HX711 - Role: Load Cell ADC - Role Details: 24-bit ADC front-end for Wheatstone bridge load cell; Channel A used for bridge input; digital interface to PIC via RB0/RB1 **Pins:** - AGND [pin 5] - AVDD [pin 3] - BASE [pin 2] - DOUT [pin 12] - DVDD [pin 16] - INA- [pin 7] - INA+ [pin 8] - INB- [pin 9] - INB+ [pin 10] - PD_SCK [pin 11] - RATE [pin 15] - VBG [pin 6] - VFB [pin 4] - VSUP [pin 1] - XI [pin 14] - XO [pin 13] ### X1 — [XIHCELNANF-4MHZ](https://www.flux.ai/lcsc/xihcelnanf-4mhz.md) - Package: HC-49US_L11.5-W4.5-P4.88 - Role: Clock Source - Manufacturer Name: TAITIEN(泰艺电子) - LCSC Part Number: C295086 - Part Type: Crystals - JLCPCB Part Class: Extended Part - Manufacturer Part Number: XIHCELNANF-4MHZ - Product Info Url: https://lcsc.com/product-detail/Others_TAITIEN-Elec-XIHCELNANF-4MHZ_C295086.html - Package or Case Code: HC-49US_L11.5-W4.5-P4.88 - Datasheet URL: https://storage.googleapis.com/graviton-electric-symbols/document_assets/lcsc/2304140030_TAITIEN-Elec-XIHCELNANF-4MHZ_C295086.pdf - Role Details: 4 MHz parallel-cut crystal for PIC16F877A XT oscillator mode **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/abeetpaul/pic16f877a-hx711-load-cell-interface](https://www.flux.ai/abeetpaul/pic16f877a-hx711-load-cell-interface).* --- *Generated from [https://www.flux.ai/abeetpaul/pic16f877a-hx711-load-cell-interface](https://www.flux.ai/abeetpaul/pic16f877a-hx711-load-cell-interface)*