PCBs
- Socket for TinyPICO ESP32 module running MicroPython - now this socket is used as interface to the second PCB, which is stacked on top.
- 8-channel servo current sensing (for estimating the servo load)
- Connector for 18-channel Maestro Mini servo controller
- Socket for 5V step-up voltage regulator module
- Connector for measuring servo battery voltage
- Connectors for piezo buzzer, 1-cell LiPo battery, potentiometer (e.g. mode selection), and I2C (Stemma QT)
- Option to auto-power-up board when servo voltage is detected
- 0.3 - Prototype
- Socket for serial HC05 BlueTooth module
- Issue: Load detection does not work by servo channel but only total current, because current sense amplifiers are connected the wrong way (polarity wrong).
- 0.4 - Updated and fixed version
- Load detection fixed
- Socket for serial HC05 Bluetooth module removed (as the TinyPICO supports BLE)
- Stemma QT I2C connector added
- Optional relay added to enable auto-powerup upon detection of servo voltage
The LED 1 (yellow, GP2) and a NeoPixel (GP3) are controlled by the "walk engine" (GP2) and, hence, activated in a program state/activity-dependent manner.
LED 2 (red) is directly connected to the error pin of the Maestro Mini servo controller and indicates servo issues. LED 3 (green) is on whenever the board is powered by the battery.
| Connector | Description | Server Pico | Client Pico. |
|---|---|---|---|
| bat | Connector to measure servo battery voltage. In addition, this input is used to auto-power-up board via a relay (see also J3) | GP28/ADC2 | |
| SC | Connector for 18-channel Maestro Mini servo controller via serial port | GP4/RX, GP5/TX COM2 |
|
| buzz | Connector for passive piezo buzzer | GP6 | |
| pot | Connector for potentiometer | GP28/ADC2 | |
| J1 | Jumper; needs to stay open to enable I2C connector | ||
| J2 | Socket for 5V step-up voltage regulator module, which supports all 5V devices of the board. Note that enable pin is not supported. | ||
| J3 | Jumper; set to shortcut relay. Then, only the power switch determines if the board is powered or not. | ||
| Cli | Connector to robotling client board to receive commands via serial connection | GP0/TX, GP1/RX COM1 |
|
| I2C | Stemma QT connector to I2C bus, with ground and 3V | GP19/SCL, GP18/SDA |
Other than in the previous design, the "client" PCB carries both Pico microcontrollers and connects to the "server" PCB via the socket that was meant to take the TinyPICO.
- Sockets for two Raspberry Pi Pico microcontrollers
- Connector for (round) TFT display (J5)
- Extension connector (J3) for additional sensors etc.
- 2x NeoPixels for indicating status of server and client
- Protection of battery when Picos are powered via USB
- Server and client are connected via serial interface plus two handshake lines
- 0.3 - Prototype
- 0.4 - Updated version
- Small changes to adapt to FeatherS2 pinout.
- Added the option to power the FeatherS2 from the LiPo connected to the "walk engine" board (including protection diode).
- 2.0 - New design for two Pico microcontrollers
Circuit diagram for new (v2.0) client PCB (also as PDF):
