Verdin Carrier Board Design Guide
Preliminary
– Subject to Change
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2.1.2
"Reserved" Interfaces
Some of the "Reserved" interfaces are adding extra functionality to an "Always Compatible"
interface. E.g. the additional USB 3.x SuperSpeed signals in the "Reserved" class are required to be
used in conjunction with the USB 2.0 Host interface signals in the "Always Compatible" class. There
are additional RTS/CTS hardware flow control signals which need to be used in conjunction with
the respective general purpose UARTs found in the "Always Compatible" class.
Since "Reserved" interfaces are possibly not provided by some modules, it is mandatory to consult
module datasheets for further information. A useful tool is the Toradex Pinout Designer which
supports comparing the available features of different Verdin modules.
If a module does not feature all possible instances of "Reserved" interfaces (defined by the Verdin
standard), interfaces will be filled in an ascending order (starting from the lowest instance index).
For example, in the Verdin standard, there are two CAN interfaces (CAN_1 and CAN_2). Both are
in the "Reserved" class. If only one CAN is required by a custom carrier board design, it is advisable
to use CAN_1. This guarantees better compatibility with other Verdin modules that e.g. feature a
single CAN interface (CAN_1) only.
Some interfaces (I
2
C and PWM) have instances that are reserved for other interfaces (e.g HDMI).
When filling interfaces during the design of Verdin SoMs, these instances are prioritized according
to the availability of the interface they belong to. For example, there are up to four I
2
C instances in
the Verdin specification (I2C_1, I2C_2_DSI, I2C_3_HDMI, I2C_4_CSI). If a SoC features only three
I
2
C instances and offers no HDMI interface but has a CSI interface, the following interface
interfaces will be provided by the module: I2C_1, I2C_2_DSI and I2C_4_CSI. As the example
shows, in these cases the indices of interfaces provided can be non-continuous.
Description
Standard
Note
GPIO
Capable
MIPI DSI
1
Primary display interface, up to 4 data lanes.
No
HDMI
1
Secondary display interface
No
RGMII
1
Backward compatibility with RMII is not mandatory
Optional
USB 3.x Host
1
Additional SuperSpeed signals that need to be used in
conjunction with the USB 2.0 Host interface
No
PCIe
1
1 lane with reference clock. Supported generation depends
on the module
No
I
2
C
3
1x reserved for DSI (might be usable as general purpose)
1x reserved for HDMI (might be usable as general
purpose)
1x reserved for CSI (might be usable as general purpose)
Yes*
QSPI
1
Backward compatible with SPI interface, independent from
general purpose SPI interface.
Yes*
UART (RX, TX)
1
Secondary operating system (real-time OS) debug port.
Might be usable as general purpose UART.
Yes*
UART (RTS, CTS)
2
Complementary hardware flow control signals for the fully
compatible general purpose UART interfaces
Yes*
CAN
2
CAN or CAN FD compatible
Yes*
MIPI CSI-2
1
Up to 4 data lanes
No
PWM
2
1x general purpose
1x reserved for display backlight control
Yes*
I
2
S
2
1x with master clock output
1x without master clock output
Yes*
GPIO
6
2x reserved for MIPI DSI
4x reserved for MIPI CSI-2
Yes
ADC
4
No*
Table 3: "Reserved" Interfaces
