Dual ETH Quad RS485 Base Board (B) for Raspberry Pi Compute Module 4, Gigabit Ethernet, 4CH Isolated RS485

SKU: 21666
Part Number: CM4-ETH-RS485-BASE-B
Brand: Waveshare



Dual ETH Quad RS485 Base Board (B) for Raspberry Pi Compute Module 4, Gigabit Ethernet, 4CH Isolated RS485, USB2.0
Dual ETH Quad RS485 Base Board for CM4

Designed For Raspberry Pi Compute Module 4

CM4 socket suitable for all variants of Compute Module 4
Networking Gigabit Ethernet RJ45 connector, 100M Ethernet RJ45 connector
Connector Isolated RS485 × 4, Power screw terminal × 1
USB USB 2.0 Type A × 2
Camera MIPI CSI-2 port × 2 (15pin 1.0mm FPC connector)
Video HDMI port × 1, supports 4K 30fps output
RTC Real-time clock with battery socket and ability to wake Compute Module 4
Storage MicroSD card socket for Compute Module 4 Lite (without eMMC) variants
Fan header allows speed adjustment, 5V
Indicator Power indicator × 1, CM4 status indicator × 1,
User LED × 2, RS485 communication indicator × 8
Power input 7-36V
Dimensions 93.6 × 108.8mm
Connecting with Compute Module 4

standard CM4 socket and suitable for all variants of Compute Module 4

More Rich Interfaces

Various Interfaces Including: Dual ETH / RS485 / CSI / FAN / HDMI / Micro SD / USB

Application Examples

Suitable For Raspberry Pi Applications requiring Multi-Channel RS485 Communication Or Other Industrial Context

for reference only, CM4, display, and cameras are NOT included.
What's On Board
  1. CM4 socket
    suitable for all variants of Compute Module 4
  2. IO-VREF
    Set the CM4 IO logic level as 3.3V (default) or 1.8V
  3. RTC-12C: 12C bus selection for RTC
    Can choose SDA0 & SCLO (default) or GPIO2 & GPIO3
  4. RTC INT: RTC interrupt pin select
    D16: Use GPIO16 to receive interrupt signal when RTC interruption (default)
    GL-EN: CM4 powerdown on RTC interruption
    PI-RUN: CM4 will reboot on RTC interruption
  5. SYSTEM: System function configuration
    WP-DIS: Prevent EEPROM from being overwritten
    BT-DIS: Disable Bluetooth function, for CM4 with antenna variant ONLY
    WIFI-DIS: Disable WiFi function, for CM4 with antenna variant ONLY
  6. Boot
    ON: CM4 will be booted from USB-C interface
    OFF: CM4 will be booted from eMMC or Micro SD card
  7. PWR & USB
    When the BOOT switch is "ON", can be used as the USB programming or DC power supply port
    When the BOOT switch is "OFF", only used as the DC power supply port
  8. HDMI0
    HDMI port, supports 4K 30fps output
  9. USB
    2x USB 2.0, for connecting sorts of USB devices
    CM4 original Gigabit RJ45 ETH
    USB extended 100M ETH
  12. CAM0 & CAM1
    2x MIPI CSI camera ports
  13. Buzzer
    GPIO22 control
  1. FAN
    4-pin FAN header, only supports 5V FAN, allows PWM speed adjustment (GPIO18 control, speed measurement is not supported)
  2. RTC battery socket
    Supports CR1220 button cell
  3. RS485 TX/RX indicator
    TXn: TX indicator for channel n
    RXn: RX indicator for channel n
  4. User LED
    USER0: GPIO20 control
    USER1: GPIO26 control
  5. PWR
    Raspberry Pi power indicator
  6. ACT
    Raspberry Pi working status indicator
  7. DC 7~36V
    DC power supply interface
  8. Power input terminal
    DC power supply terminal, supports 7~36V wide range power input
  9. RS485 terminal
    4 x Isolated RS485 terminal with a spacing of 5.08mm
  10. Jumper
    120R Balance Resistor Selection Jumper
  11. RS485 operating mode selection
    Full-auto: automatic mode, easy for program operation but the load capacity is weak
    Semi-auto: semi-automatic mode, which requires manual TX/RX switching, with high reliability and strong load capacity
  12. Encryption chip
    ATSHA204 encryption chip, providing multiple encryption to ensure data security and reliability
  13. Micro SD card slot
    for connecting a Micro SD card with pre-burnt image (Lite variant ONLY)
Outline dimensions
What's the differences
CM4 Base BoardInterface count and specifications

      2.0×1     ×1     5V CM4 sized

  ×1   2.0×1 ×1 ×1 ×1     5V CM4 sized

      2.0×1 ×1 ×1 ×1     5V Onboard Camera

      M.2 M 2.0×1   ×1 ×1     5V Arduino compatible

mini Base A
  ×1 M.2 M 2.0×4 ×1 ×2 ×2   5V 5V mini size

mini Base B
  ×1 M.2 M 2.0×4 ×1 ×2 ×2 5V 5V mini size

mini Base C
  ×1 M.2 M 2.0×2   ×1 ×2 5V 5V Dedicated 40PIN LCD Connector

Touch screen
  ×1   M.2 M 2.0×4   ×1 ×1     5V IPS screen

Mini Dual Gigabit
  ×2   2.0×1         5V SH1.0 5V dual ETH

Binocular camera
  ×1 M.2 M 2.0×4   ×2       5V dual 8MP

4CH RS485
  ×1     2.0×2   ×1 ×2 ×1 5V 7-36V dual ETH

  ×1 M.2 E 2.0×3 ×1 ×2 ×2 ×1 5/12V 7-36V WIFI6 dual ETH

Dual Gigabit ETH
  ×2   3.0×3 ×1 ×2 ×2 5/12V 7-36V  

IoT Dual Gigabit ETH
  ×2   3.0×2 ×1 ×2 ×2 5/12V 5V 5G/4G support

IoT Base
×1   Gen2×1 2.0×2 ×2 ×2 ×2 5/12V 7-36V 5G/4G support

PoE Base (B)
×1 Gen2×1 2.0×4 ×2 ×2 ×2 5/12V 5V RS232

PoE UPS Base
×1 M.2 M 2.0×4 ×1 ×2 ×2 5/12V 7-36V UPS

PoE Base
×1   3.0×4 ×2 ×2 ×2 5/12V 7-36V  

Raspberry Pi official
×1 Gen2×1 2.0×4 ×2 ×2 ×2 12V 12V  

Wireless base
  ×1   M.2 B /
2.0×3   ×1 ×1 5/12V 5V or
5G/4G support

5″ touch screen
×1 M.2 M 2.0×4   ×1 ×2 5/12V 5V  

7″ all-in-one
  ×1   M.2 M 2.0×4 used ×1 used 5/12V
7-36V touch screen
Note ① USB 3.0 is equivalent to USB 3.2 Gen1
② There's PoE header only on the Raspberry Pi official IO board without PoE circuit, that means additional PoE module is required for the official IO board to enable PoE feature.
Unless otherwise specified, the PoE feature here stands for integrating 802.3af-compliant PoE circuit (5V/2.5A).
Resources & Services

* Resources for different product may vary, please check the wiki page to confirm the actually provided resources.

Weight: 0.1 kg

Quick Overview

  1. CM4-ETH-RS485-BASE-B x1