This Mini Base Board (B) for the Raspberry Pi Compute Module 4 is a compact CM4 breakout option offering a good set of features with a small footprint. Two versions of this board are available - Lite (A) or Full (B). This is the Full (B) version which comes with the additional Real-time Clock (RTC) and fan speed control. With its M.2 slot, MicroSD card slot, Real-Time Clock, dual-CSI ports for camera modules and a host of other features, it's a great base for any CM4 project you're planning. Note: Compute Module, M.2 SSD and RTC battery not included Features The CM4 Mini base board offers the following connectivity options and features: * 40-pin Raspberry Pi GPIO header * 1x RJ45 Gigabit Ethernet * 2x USB 2.0 ports * 1x Full-size HDMI port * 1x M.2 slot (Supports NVME SSD or communication modules with PCI-E M.2 KEY-M interface) * 1x MicroSD slot * 1x Real-Time Clock (RTC) (battery not included) * 2x CSI Camera ports * 1x DSI Display port * 1x USB 2.0 FFC Connector * 1x HDMI FFC Connector * 1x 4-pin fan header * USB-C programming/power port Specification POE N/A USB USB 2.0 × 2 USB 2.0 × 2 (via FFC connector) GPIO Raspberry Pi 40PIN GPIO × 1 HEADER M.2 slot × 1 HDMI HDMI × 2 (1x via FFC connector) Supports 4K 30fps output DSI DISPLAY MIPI DSI × 1 (15pin 1.0mm FPC) CSI CAMERA MIPI CSI-2 × 2 (15pin 1.0mm FPC) POWER INPUT 5V FAN 5V Allows speed adjustment and measurement RTC Real-time clock with battery socket and ability to wake Compute Module 4 RJ45 ETHERNET Gigabit Ethernet CM4 SOCKET Suitable for all variants of Compute Module 4 SD CARD SLOT MicroSD card socket for Compute Module 4 Lite (without eMMC) variants DIMENSIONS (MM) 85.0 × 56.0 What's Onboard 1) CM4 socket - Suitable for all variants of Compute Module 4 2) Power input/Programming - 5V/2.5A power supply, or used for eMMC burning 3) DISP - MIPI DSI display port 4) Fan - For connecting cooling fan, allows speed adjustment and measurement 5) Camera - 2x MIPI CSI camera ports 6) HDMI0 connector - HDMI0 port, supports 4K 30fps output 7) USB 2.0 ports - 2x USB 2.0 ports, for connecting USB devices 8) Gigabit Ethernet connector - Gigabit Ethernet RJ45 connector, with 10 / 100 / 1000M network support 9) M.2 indicator - Indicating the operating status of M.2 interface 10) ACT indicator - Indicating the operating status of Raspberry Pi 11) PWR indicator - Indicating the status of Raspberry Pi power supply 12) BOOT selection - ON: CM4 would be booted from USB-C interface - OFF: CM4 would be booted from eMMC or Micro SD card 13) 40-pin GPIO header 14) Micro SD card slot - For connecting a Micro SD card with pre-burnt image (Lite variant ONLY) 15) HDMI1 FFC connector - HDMI1 port, supports 4K 30fps output 16) USB 2.0 FFC connector - Can be connected through an adapter 17) FE1.1S - USB HUB chip, expanding one USB port to 4x ports 18) M.2 slot - Supports NVME SSD, or communication modules with PCI-E M.2 KEY-M interface 19) RTC chip - Allows RTC-related functions like wakeup, shutdown, reboot, and more 20) RTC interrupt selection - PI-RUN: CM4 reboot on RTC interruption - GN-EN: CM4 shutdown on RTC interruption - D4: D4 pin is triggered on RTC interruption 21) EMC2301 - Fan controller, for speed adjustment/measurement 22) RTC battery holder - Supports CR1220 button cell Resources * Product Wiki Package Contents * 1x CM4 Mini Base Board (B) * 1x SSD Mounting Screw Compute Module, M.2 SSD and RTC battery not included https://elecena.pl/product/22723026/mini-base-board-b-for-raspberry-pi-compute-module-4-rev-4 2023-03-07 https://elecena.pl/product/22723026/mini-base-board-b-for-raspberry-pi-compute-module-4-rev-4 2023-12-27 https://elecena.pl/product/22723026/mini-base-board-b-for-raspberry-pi-compute-module-4-rev-4 2024-09-19 https://elecena.pl/product/22723026/mini-base-board-b-for-raspberry-pi-compute-module-4-rev-4 2024-11-29 https://elecena.pl/product/22723026/mini-base-board-b-for-raspberry-pi-compute-module-4-rev-4 2024-11-30 https://elecena.pl/product/22723026/mini-base-board-b-for-raspberry-pi-compute-module-4-rev-4 2025-08-05 https://elecena.pl/product/22723026/mini-base-board-b-for-raspberry-pi-compute-module-4-rev-4 2025-11-28 https://elecena.pl/product/22723026/mini-base-board-b-for-raspberry-pi-compute-module-4-rev-4 2025-11-29