Datasheet
Table Of Contents
- Raspberry Pi Compute Module 4 IO Board
- Colophon
- Chapter 1. Introduction
- Chapter 2. Features
- 2.1. CM4 Module Connectors
- 2.2. PSU input
- 2.3. Dual Full size HDMI 2.0 connectors
- 2.4. Gigabit Ethernet RJ45
- 2.5. USB 2.0 Hub
- 2.6. Micro USB connector
- 2.7. Micro SD Card socket
- 2.8. PCIe Gen 2 x1 socket
- 2.9. Fan connector
- 2.10. Dual DSI display connectors ( 22pin 0.5mm pitch cable)
- 2.11. Dual CSI-2 display connectors ( 22pin 0.5mm pitch cable)
- 2.12. A Raspberry Pi HAT connector
- 2.13. Real Time Clock (RTC)
- 2.14. Jumpers
- 2.15. LEDs
- Chapter 3. Mechanical Diagram
- Chapter 4. Circuit Diagram
Note the PCIe Interface doesn’t support MSI-X. Typically PCIe devices will fall back to MSI.
2.9. Fan connector
This connector supports standard +12V FANs with PWM drive and tacho output. An EMC2301 controls the fan via I2C.
Mating connector part number Molex 47054-1000 or similar. The +12V power for the fan comes from the +12V input and
isn’t regulated.
TIP
To enable the I2C bus to the fan controller you will need dtparam=i2c_vc=on set in config.txt . The fan controller then
will be on i2c-10 address 0x2f ( 7bit address)
2.10. Dual DSI display connectors ( 22pin 0.5mm pitch cable)
Both DSI interfaces ( 2 channel and 4 channel) are brought out to separate 22way 0.5mm pitch connectors. These
connectors are the same as on the existing CMIO board, NB they are different from the Raspberry Pi 4, Model B. If the
DSI0 interface ( 2 channel ) is used then the 2 jumpers on J6 must be fitted to route the I2C bus to the connector
2.11. Dual CSI-2 display connectors ( 22pin 0.5mm pitch cable)
Both CSI-2 interfaces ( 2 channel and 4 channel) are brought out to separate 22way 0.5mm pitch connectors. These
connectors are the same as on the existing CMIO board, NB they are different from the Raspberry Pi 4, Model B. If the
CSI0 interface ( 2 channel ) is used then the 2 jumpers on J6 must be fitted to route the I2C bus to the connector
2.12. A Raspberry Pi HAT connector
The Raspberry Pi Compute Module 4 IO Board has a standard Raspberry Pi 40 way HAT connector. The mounting holes
are also provided so that standard HATs may be used.
2.13. Real Time Clock (RTC)
A PCF85063AT RTC is provided on the Raspberry Pi Compute Module 4 IO Board. A battery socket is provided for a
CR2032 battery. On initial setup the CLKOUT of the RTC should be disabled to save power.
The alarm output of the RTC is used to wakeup the CM4 from a previous shutdown. If an alarm goes off during normal
operation the CM4 will be reset, this can be used as a watchdog timer if required.
TIP
To enable the I2C bus to the RTC you will need dtparam=i2c_vc=on set in config.txt . The RTC then will be on i2c-10
address 0x51 ( 7bit address)
2.14. Jumpers
R4/R5 Vref Voltage Selection
By default the Raspberry Pi Compute Module 4 IO Board sets the CM4 IO voltage to +3.3v via R5. Moving R5 to R4 sets
the IO voltage on the CM4 to +1.8v . Moving the resistor requires the use of the soldering iron.
Raspberry Pi Compute Module 4 IO Board
2.9. Fan connector 6