Clean sequential pin layout utilizing 0 & 1 for OLED, 15 for PWM output, and 26, 27, 28 for Hardware ADC Potentiometers.
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RP2040-Zero Board Map
RST
BOOT
RP2040
RP2040-Zero
0 (SDA)
1 (SCL)
2
3
4
5
6
7
15 (PWM)
26 (ADC0)
27 (ADC1)
28 (ADC2)
29
3V3
GND
5V
USB-C
Yellow wire connects to pad 15 (Top Right). OLED uses pads 0 & 1 (Top Left).
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RP2040-Zero Pin Matrix
Board Pad
Signal Type
Target Device
Notes & Why This Pin
0 (Top Left)
GPIO 0 (SDA)
SSD1306 OLED SDA
Starts cleanly right at Pin 0
1 (Left)
GPIO 1 (SCL)
SSD1306 OLED SCL
Sequential Pin 1
15 (Top Right)
GPIO 15 (PWM)
TPA3118 IN+
Yellow Wire (40 kHz Carrier)
26 (Right)
ADC0 (GPIO 26)
Potentiometer 1
Carrier Freq (38 – 42 kHz) *Required ADC
27 (Right)
ADC1 (GPIO 27)
Potentiometer 2
Modulation Rate (50 – 300 Hz) *Required ADC
28 (Right)
ADC2 (GPIO 28)
Potentiometer 3
Drive Level (1% – 20%) *Required ADC
3V3 (Right)
3.3V Power
OLED & Pots VCC
3.3V Power Output
GND (Right)
Ground
OLED, Pots, TPA3118 IN-
Shared Common Ground
🔍 Silkscreen Misalignment Notice: On RP2040-Zero boards, the text label "29" is printed twice due to PCB silk text offset. Count physical pads starting from the corner pad (Yellow Wire) going up towards USB-C:
Pad 8 (Corner / Yellow Wire): GP15 (PWM Output)
Pad 7 (1 pad up from yellow): GP26 (Pot 1 - Carrier)
Pad 6 (2 pads up from yellow): GP27 (Pot 2 - Mod Rate)
Pad 5 (3 pads up from yellow): GP28 (Pot 3 - Drive Level)
Pad 4 (4 pads up from yellow): GP29
Pad 3: 3V3 • Pad 2: GND • Pad 1 (USB): 5V
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TPA3118 Signal
Connected to pad 15 (Yellow wire). Softened with 2mA drive strength.
⚡ GPIO 15 Output: 40 kHz ultrasound square wave.
🛡️ Drive Limit: Capped at 20% duty cycle to prevent amp distortion.
🔗 Shared Ground: Connect GND pad to TPA3118 IN-.
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Pot Controls
Pads 26, 27, 28 read analog potentiometers with EMA smoothing.