User Interface PCBA

Note

The User Interface PCBA is only available on the TurtleBot 4 and NOT the TurtleBot 4 Lite.

Overview

The TurtleBot 4 comes with an additional User Interface board that expands on the Raspberry Pi 4 functionality to give the user ease of control over the Create 3 robot and Raspberry Pi and to act as an expansion board for addons, sensors, gadgets the user might have in mind to utilize.

TurtleBot 4 UI Board
TurtleBot 4 User Interface PCBA

User I/O

The TurtleBot 4 has a 2x20 pin internal connector connecting it to the Raspberry Pi via a flex cable, and another 2x12 pin connector allowing the user to access the remaining GPIOs and a set of 5V, and 3.3V power pins coming from the Raspberry Pi.

The IO interface between the 2x20 connector and 2x12 connector and the available GPIOs to the user are shown in Table 1, and 2. The GPIO numbers are a direct match to the Raspberry Pi 4 GPIO.

Table 1: 2x20 RPi Connector Pinout
GPIO # Function Pin # Pin # Function GPIO #
3V3_RPi 1 2 5V_RPi
GPIO2 USER_PORT 3 4 5V_RPi
GPIO3 USER_PORT 5 6 GND
GPIO4 SDA 7 8 USER_PORT GPIO14
GND 9 10 USER_PORT GPIO15
GPIO17 PWR_LED 11 12 MTR_LED GPIO18
GPIO27 COMM_LED 13 14 GND
GPIO22 BATT_GRN_LED 15 16 BATT_RED_LED GPIO23
3V3_RPi 17 18 WIFI_LED GPIO24
GPIO10 USER_PORT 19 20 GND
GPIO9 USER_PORT 21 22 USER1_GRN_LED GPIO25
GPIO11 USER_PORT 23 24 USER_PORT GPIO8
GND 25 26 USER_PORT GPIO7
GPIO0 EEPROM_SD 27 28 EEPROM_SC GPIO1
GPIO5 SCL 29 30 GND
GPIO6 USER2_GRN_LED 31 32 USER_PORT GPIO12
GPIO13 DISPLAY-RST 33 34 GND
GPIO19 USER_SW1 35 36 USER_SW2 GPIO16
GPIO26 USER_SW3 37 38 USER_SW4 GPIO20
GND 39 40 USER2_RED_LED GPIO21
Note

ALL USER_PORTs are routed to the 2X12 Auxiliary connectors

Table 2: 2x12 User I/O Pinout
GPIO # Function Pin # Pin # Function GPIO #
3V3_RPi 1 2 5V_RPi
GPIO2 USER_PORT 3 4 5V_RPi
GPIO3 USER_PORT 5 6 GND
GND 7 8 USER_PORT GPIO14
3V3_RPi 9 10 USER_PORT GPIO15
GPIO0 EEPROM_SD 11 12 EEPROM_SC GPIO1
GPIO10 USER_PORT 13 14 GND
GPIO9 USER_PORT 15 16 GND
GPIO11 USER_PORT 17 18 USER_PORT GPIO8
GND 19 20 USER_PORT GPIO7
GND 21 22 USER_PORT GPIO12
GND 23 24 GND

User Power

In addition to these GPIO ports, the user has two additional power ports available supplying 3.3V, 5V, 12V, VBAT (14.4V), and two grounds each.

TurtleBot 4 UI Power Connectors
TurtleBot 4 Additional Power Ports

The pinout and power ratings can be found in Table 3.

Table 3: User Power Port Pinout
Pinout Source Max current output (mA) Fuse Hold at (mA)
1 VBAT 300 350
2 12V 300 350
3 GND
4 5V 500 500
5 3V3 250 300
6 GND

Molex Picoblade 6-Pin cable assembly

The two connectors are both 6-Pin Molex PicoBlade P/N 0532610671. The cable assembly needed to use these connectors are P/N 0151340602.

Molex PicoBlade: 0532610671 Molex PicoBlade: 0151340602
Molex PicoBlade: Connector 0532610671 (left) and Cable 0151340602 (right)

User USB-C Ports

The are 4 USB-C ports that go through an integrated hub on the User Interface board and connect to the Raspberry Pi through a single USB 3.0 cable. The current available to all 4 ports is 3A. Additionally, each individual port is current limited to 3A. In other words, each port is capable of supplying 3A if the others aren't in use, or the available 3A is shared amongst ports that are in use. The bandwidth for communication is split among 4 dynamically depending on how many of the ports are communication at once, and is limited by the USB 3.0 connection to the Raspberry Pi.

Note

On the REV 2 board only port 4 can supply 3A. The other three ports can supply 2.6A +/- 0.1A. The revision and port numbers are labeled on the underside of the PCBA.