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Smart Kart Notes Scales — Block Diagram

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Smart Kart Notes Scales — Block Diagram Functional blocks and sourcing decision
  • Power/GPIO interface: no matching validated reference found; source real 2×20 Raspberry Pi header from library.
  • LF/LR/RF/RR HX711 channels: no matching HX711/load-cell validated reference found; implement four identical blocks from the HX711 manufacturer reference circuit and datasheet.
  • Mechanical: four configurable M3 non-plated mounting holes.
Channel connector contract
  1. E+
  2. E−
  3. A+
  4. A−
  5. SHIELD → PCB GND only
  6. SPARE → intentional no-connect
No PCB placement or routing is included in this phase.

Power Budget

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Power Budget
Source: Raspberry Pi 3.3 V rail through the 2×20 GPIO header.
The board contains four HX711 channels and no other active loads. Final current figures will be populated from the selected HX711 datasheet before schematic completion. The design target is to remain far below the Raspberry Pi 3.3 V rail capability, with margin for all four bridge-excitation regulator circuits and ADC operation.

flux

Renamed the project Smart Kart Notes Scales and added its production-board description. No schematic components or nets were added because the build stopped when no ACUs were available.
Remaining work: complete and verify the four-channel HX711 schematic, then proceed through PCB placement and routing after the required phase reviews.
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Smart Kart Notes Scales — Block Diagram
Text
Raspberry Pi 2×20 GPIO Header
  ├─ 3V3 ───────────────┬─ LF HX711 + load-cell terminal + test points
  │                     ├─ LR HX711 + load-cell terminal + test points
  │                     ├─ RF HX711 + load-cell terminal + test points
  │                     └─ RR HX711 + load-cell terminal + test points
  ├─ GND ───────────────┴─ common PCB ground (including connector SHIELD pins)
  ├─ GPIO17 ─────────────── shared HX711_CLOCK
  ├─ GPIO22 ─────────────── LF_DATA
  ├─ GPIO23 ─────────────── LR_DATA
  ├─ GPIO24 ─────────────── RF_DATA
  └─ GPIO25 ─────────────── RR_DATA
Functional blocks and sourcing decision
  • Power/GPIO interface: no matching validated reference found; source real 2×20 Raspberry Pi header from library.
  • LF/LR/RF/RR HX711 channels: no matching HX711/load-cell validated reference found; implement four identical blocks from the HX711 manufacturer reference circuit and datasheet.
  • Mechanical: four configurable M3 non-plated mounting holes.
Channel connector contract
  1. E+
  2. E−
  3. A+
  4. A−
  5. SHIELD → PCB GND only
  6. SPARE → intentional no-connect
No PCB placement or routing is included in this phase.

  • Functional blocks and sourcing decision

  • Channel connector contract

Smart Kart Notes Scales

Smart Kart Notes Scales thumbnail
Production four-channel 200 kg load-cell ADC board using dedicated HX711 converters and a Raspberry Pi 40-pin GPIO interface, optimized for low analog noise and enclosure mounting.

Properties

3.3

V

ADC Board Rev A

Raspberry Pi GPIO

Pricing & Availability

Distributor

Qty 1

Arrow

$11.84–$13.99

Digi-Key

$5.38–$5.78

HQonline

$8.09–$8.14

LCSC

$14.20–$14.64

Mouser

$23.55

TME

$15.80

Verical

$16.42–$20.36

Controls