Three AA cells in BT20 next to USB: through an SS14 D20 onto VIN behind J1, so that neither feeds the other.
Why: Cells beside USB on one rail is a common supply of a maker board. It holds the cells' current and the diode that keeps the two sources from feeding each other.
Domains on: core power · SVG
Reference: power
led-bar · board main
graph v1.0 (2026-10-25) · 276 x 374 mm
drawn by edakit schematic draw – change the graph, not this drawing
Power Input
J1: 5 V from a USB power supply (JST PH, pin 1 = VIN)
D1 SS34: reverse-polarity protection
MCU
Raspberry Pi Pico 2 module; VSYS from +5V, 3V3(OUT) supplies U2
Spare: GP0, GP1, GP7, GP8, GP9, GP10, GP11, GP12, GP13, GP14, GP15, GP16, GP17, GP18, GP19, GP20, GP21, GP22, GP26, GP27, GP28
GP net function
GP2 LED_CLK out, SPI SCK
GP3 LED_SDI out, SPI TX
GP4 LED_LE out, latch
GP5 LED_OE out, PWM, active low
GP6 BTN in, pull-up
LED Driver
TLC5916: I_OUT = 15 x 1.26 V / R1 = 9.45 mA
R2 keeps OE high until the firmware runs
Notes
Nets with the same name are connected (labels and power flags).
Source: graph.json v1.0 (2026-10-25)
Drawn by edakit schematic draw – change the graph, not this sheet.
Battery
BT20: three AA cells, D20 SS14 onto +5V
neither USB nor the cells feed the other
Other
LED_CLK
LED_CLK
LED_SDI
LED_SDI
LED_LE
LED_LE
LED_OE
LED_OE
BTN
LED0
LED1
LED2
LED3
LED4
LED5
LED6
LED7
REXT
BAT
VIN
3V3
+5V
+5V
+5V
+5V
+5V
+5V
+5V
+5V
+5V
3V3
3V3
+5V
+5V
VIN
1
2
J1
B2B-PH-K-S(LF)(SN)
GND
3
GP2
4
GP3
5
GP4
6
GP5
7
GND
8
GP6
9
GND
13
GND
18
GND
23
GND
42
VSYS
39
GND
38
3V3(OUT)
36
AGND
33
GND
28
U1
Raspberry Pi Pico 2
SW1
C2
22uF
GND
1
SDI
2
CLK
3
LE(ED1)
4
OUT0
5
OUT1
6
OUT2
7
OUT3
8
VDD
16
R-EXT
15
OE(ED2)
13
OUT7
12
OUT6
11
OUT5
10
OUT4
9
U2
TLC5916IDR
D2
green
D3
green
D4
green
D5
green
D6
green
D7
green
D8
green
D9
green
R2
10k
R1
2k
C1
100nF
+
BT20
D20
D1
SS34
Seeded fault Codes it raises the cells' current limit LIM.ino diode in front of the cells PATH.reverse
