Arduino Nano驱动4位7段数码管显示温度故障排查求助

Hey there! As someone who’s debugged plenty of Arduino 7-segment display circuits starting out, let’s focus on the hardware checks first since your test program works (so individual digits are functional). Here’s a step-by-step breakdown to troubleshoot your setup:

1. Fix the Common Anode Display’s Current Limiting (Critical!) #

Your Kingbright CA56-12SRWA is a common anode display—meaning each digit’s common pin needs to go HIGH to activate it, and segments light up when pulled LOW. The 2-second full-off cycle you’re seeing is almost certainly an Arduino brownout reset, caused by too much current being drawn from your GPIO pins.

Here’s what to check:

• You mentioned 4x 220Ω resistors for the display—are these on the segment lines (from 74HC595 outputs to the display’s a-g/decimal pins)? If yes, that’s correct. But you’re likely missing resistors on the digit common lines (A0/A3/A2/A1 to the display’s common anode pins).
• Add a 220Ω resistor between each digitPin (A0, A3, A2, A1) and the display’s corresponding common anode pin. This limits the current flowing through the activated digit, preventing the Arduino from resetting.

2. Verify 74HC595 Shift Register Wiring #

Double-check these critical connections—even a loose wire here can kill your display output:

• VCC → 5V (same as Arduino Nano), GND → shared ground.
• SER (data input) → Arduino pin 6 (dataPin).
• SRCLK (clock) → Arduino pin 4 (clockPin).
• RCLK (latch) → Arduino pin 5 (latchPin).
• OE (Output Enable) → tie directly to GND (if left floating, the shift register outputs will be in a high-impedance state, so segments won’t light up).
• SRCLR (Clear) → tie directly to 5V (if tied to GND, it clears all shift register data, keeping segments off).

3. Confirm DHT11 Wiring (and Data Validity) #

Your DHT11 uses a 1kΩ pull-up resistor—make sure it’s wired correctly:

• VCC → 5V, GND → shared ground.
• Signal pin → Arduino pin 7, with a 1kΩ resistor between the signal pin and 5V (this pull-up is mandatory for the sensor to communicate properly).
• Quick check: Open the Serial Monitor (9600 baud) and see if it’s printing valid temperature values. If you’re seeing 0.00 or NaN, the sensor isn’t sending data, which would populate your digitBuffer with 0s—explaining why nothing shows up.

4. Isolate the Problem with a Hardcoded Test #

Since your test program works, let’s rule out code/data issues temporarily:

1. Comment out all DHT11-related code in loop():

   // float h = dht.readHumidity();
   // float t = dht.readTemperature();
   // float hi = dht.computeHeatIndex(t, h, false);
   

2. Hardcode your digitBuffer to a known value:

   digitBuffer[3] = 1;
   digitBuffer[2] = 2;
   digitBuffer[0] = 3;
   digitBuffer[1] = 4;
   

3. Upload this modified code. If the display shows 12.34, the problem is with the DHT11 data (either bad sensor wiring or invalid readings). If nothing shows up, go back to rechecking the 74HC595 and display wiring.

5. Power Supply Check #

If you’re powering the Arduino via USB, make sure you’re using a high-quality cable (cheap cables can cause voltage drops). If the display still misbehaves, try powering the Arduino with an external 5V power supply (make sure it can handle at least 200mA of current for the display).

内容的提问来源于stack exchange，提问作者jdsflk