Electronics, PCB and parts
Note: The pictures show PCB version v0.2, which differs slightly from the current version v0.4 (see below).
Top side of board (w/o Display Pack; see inset):
Bottom side of board w/ RP2040 Pico:
| Connector | Description | MicroPython |
|---|---|---|
| J1 | Battery connector (e.g. a 2x AAA battery pack) | |
| J2 | Socket for a 5V step-up voltage converter module, which supplies all 5V functions on the board. | |
| J3 | Selects the voltage source for the Pico. With sensor port to the left, setting the jumper [oo]o connects the Pico to the 5V step-up voltage converter, o[oo] connects it directly to the battery | |
| J4 | Auxiliary connector w/ D9, 5V and ground |
|
| M1,2,3 | Connectors for servos 1, 2 and 3, with D marking the digital signal (usually yellow) |
|
| Sensor port | From top left to bottom right: | |
| UART channel 1 I²C Analog-in channel 0 Analog-in channel 1 Digital I/O pins Analog-in channel 2 |
D4(rx),D5(tx) D0(sda),D1(scl) D26(ADC0) D27(ADC1) D3,D22 D28(ADC2) |
|
| Note that except for the I²C connector, which has a 3V line, all connectors feature 5V support and ground. |
The current version is v0.4, which is shown here:
-
v0.4 - Minor revisions
- Pin 22 now available at the sensor port
- Pin 9 available via a new 3-pin socket (w/ ground and 5V), e.g. for a NeoPixel (not yet tested)
-
v0.3 - Minor revisions
- Servo motor M3 nows uses pin 21 instead of pin 9, because pin 9 is affected by the pico display board (ie. the PWM control of the RGB LED; for details, see here)
- A new jumper (J3) allows to select from which voltage source the Pico is supplied - directly the battery or the 5V step-up converter. Supplying the Pico directly from 2 AAA batteries seem to have the disadvantage that even when the batteries are still quite o.k., voltage drops (e.g. by activating the motors) cause the Pico to reboot.
- v0.2 - Initial release
| Label(s) | Part | Supplier | |
|---|---|---|---|
| J1 | 1x | 2x1 pin male header | |
| J3, J4, M1-3 | 5x | 3x1 pin male headers | |
| Sensor port | 1x | 10x2 pin angled male header | Reichelt MPE 088-2-020 |
| J2 | 1x | Pololu 5V Step-Up Voltage Regulator U1V10F5 | Eckstein PO2564 |
| S1 | 1x | Switch | Eckstein AF805 |
| S2 | 1x | Button | |
| Q1 | 1x | MOSFET DMG2305UX | Mouser DMG2305UX |
| LED1 | 1x | 3-mm LED | |
| R1, R3, R4 | 3x | 1kΩ | |
| R2, R5, R6 | 3x | 1.5kΩ | |
| R7, R8 | 2x | 8.2kΩ | |
| R9 | 1x | 220Ω | |
| Microcontroller | 1x | Raspberry Pi Pico | e.g. Reichelt RASP PI PICO |
| Display | 1x | 1.14" RGB LCD Pico Display Pack (Pimoroni) | e.g. Elektorstore 19762 |
| Battery | 1x | 3,7V 1200mAh LiPo battery, JST-PH Connector | Eckstein ZB07002 |
| Charger | 1x | e.g. Adafruit Micro Lipo w/MicroUSB Jack - USB LiIon/LiPoly charger | Exp-Tech EXP-R15-414 |
| Servo motors | 3x | Tower Pro MG90 or compatible micro servo | |
| Distance sensors | 3x | Pololu Distance Sensor w/ Pulse Width Output 50cm |
Exp-Tech EXP-R25-1516 |