Adding LEDs to Schematic

chunkermonkey

chunkermonkey

can you add a seperate 5.1kohm resister for each led?

flux

I’ll replace the shared LED ground resistor approach with five individual 5.1 kΩ resistors, one in series with each LED cathode to ground, then verify the updated LED nets.

flux

Done so far:
  • Added four new 5.1 kΩ resistors: R_LED2, R_LED3, R_LED4, R_LED5
  • Reused the existing R_LED_GND as the individual resistor for LED1
  • Broke the old shared LED cathode net
  • Rewired each LED cathode through its own resistor to ground:
    • LED1:K → R_LED_GND → GND
    • LED2:K → R_LED2 → GND
    • LED3:K → R_LED3 → GND
    • LED4:K → R_LED4 → GND
    • LED5:K → R_LED5 → GND
I was blocked before I could run the final verification/review pass. The remaining step is to verify the LED nets and run ERC checks to confirm there are no new schematic issues.
Run LED ERC
Check LED current
Rename LED resistors
Show LED wiring
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Alarm Clock Design Notes
Current power architecture — single barrel jack cable
The design now uses one external regulated 12 V DC barrel-jack adapter.
Power path:
  1. J_PWR barrel jack center pin = 12V_IN.
  2. J_PWR barrel jack terminal = GND.
  3. 12V_IN powers the KR1201A module power input:
    • J_KR1201A:2 = V+
    • J_KR1201A:1 = V-
  4. 12V_IN also feeds PS_5V_BUCK, a 12 V to 5 V buck converter module.
  5. PS_5V_BUCK output creates the 5V rail.
  6. 5V powers:
    • Arduino Micro U1:+5V
    • SG90 servo header J_SERVO:5v
    • display/LED support circuitry
    • relay-input pull-up R_KR_PULLUP
The Arduino VIN pin remains intentionally unused. Do not connect 12 V to the Arduino +5V pin. Do not power the servo from the Arduino onboard regulator.
KR1201A wiring from supplied image
The module image shows a 12 V-powered relay receiver board with terminals:
  • V- = 12 V negative / ground
  • V+ = 12 V positive
  • NO = normally-open relay contact
  • COM = relay common
  • NC = normally-closed relay contact
Schematic representation:

Table

Header pinFunctionNet
J_KR1201A:1V-GND
J_KR1201A:2V+12V_IN
J_KR1201A:3NOKR_RELAY_SENSE
J_KR1201A:4COMGND
J_KR1201A:5NCNo-connect
The relay contact is used as a dry-contact Arduino input:
  • R_KR_PULLUP pulls KR_RELAY_SENSE up to 5V.
  • KR1201A COM is tied to GND.
  • KR1201A NO connects to KR_RELAY_SENSE and Arduino U1:0/RX.
  • When the relay closes, the Arduino input is pulled LOW.
  • No 12 V is connected to the Arduino input.
5641AS-1 display reference
From the uploaded datasheet:
  • Model: 5641AS
  • Type: 0.56 inch, 4-digit, common-cathode, red 7-segment LED display
  • Typical forward voltage: 1.8 V at 10 mA
  • Continuous forward current per dice: 30 mA max
Pinout used:

Table

Display pinFunction
1Segment E
2Segment D
3Decimal point
4Segment C
5Segment G
6Digit 4 common cathode
7Segment B
8Digit 3 common cathode
9Digit 2 common cathode
10Segment F
11Segment A
12Digit 1 common cathode
Arduino pin allocation

Table

Arduino Micro pinNet / function
+5VBuck-derived 5 V rail
GND, GND__1Ground
0/RXKR1201A relay dry-contact sense input
A0-A4LED1-LED5 anode controls
13(PWM)Servo PWM signal
4/A6Display segment A
5(PWM)Display segment B
6(PWM)/A7Display segment C
7Display segment D
8/A8Display segment E
9(PWM)/A9Display segment F
10(PWM)/A10Display segment G
11(PWM)Display decimal point
RX_LED/SSDisplay digit 1 common-cathode drive via 330 ohm resistor
12/A11Display digit 2 common-cathode drive via 330 ohm resistor
A5Display digit 3 common-cathode drive via 330 ohm resistor
1/TXDisplay digit 4 common-cathode drive via 330 ohm resistor
Power budget
Approximate load budget:

Table

RailLoadTypicalPeak / note
12V_INKR1201A moduleunknownverify module label/datasheet
12V_INBuck input reflected currentabout 0.3-0.6 Adepends on 5 V load and buck efficiency
5VArduino Micro25-50 mAdepends on onboard activity
5V5 green LEDs through shared 5.1 kΩ resistor<5 mA totaluser-requested shared resistor
5V5641AS-1 displayfirmware-dependentmultiplexed display current
5VSG90 servo100-250 mA moving650 mA or more at stall/startup
Recommended adapter: regulated 12 V DC, at least 1 A. Use 12 V / 2 A for better servo and KR1201A margin. Buck converter should be set to 5.0 V before connecting the Arduino.
Important design caveats
  • Verify the KR1201A module is the 12 V version before powering it from 12V_IN.
  • Set and measure the buck output at 5.0 V before inserting the Arduino or servo.
  • A single shared 5.1 kΩ resistor for five independent LEDs is not best practice. Proper independent LEDs should each have their own current-limiting resistor.
  • The KR1201A relay contact is isolated/dry-contact style in this schematic. Do not wire the module's switched 12 V output directly to any Arduino pin.
  • Driving a servo from the same 5 V rail as the Arduino can cause resets during stall current. C_SERVO_BULK helps, but a strong 12 V adapter and adequate buck converter are required.

    Current power architecture — single barrel jack cable

    KR1201A wiring from supplied image

    5641AS-1 display reference

    Arduino pin allocation

    Power budget

    Important design caveats

Documents

    Alarm Clock Design Notes

    Firmware Starter — Arduino Micro Alarm Clock

    Board Bring-Up Plan — Alarm Clock

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