I'm designing an industrial carrier board for a Raspberry Pi
Compute Module 4 (CM4) for cryptographic image signing in a
manufacturing quality-control application (ISO 9001 process
traceability). The board captures inspection images on a
production line and signs each one cryptographically at the
point of capture using a hardware TPM, binding the image to
traceability metadata (part serial, station ID, timestamp).
Constraints:
Pin-compatible with both CM4 and CM5 (avoid CM5-reassigned
pins: 16, 19, 159, 163, 165, 169, 171)
Powered via standard 802.3at PoE+ (48V) over a single
Ethernet cable, no separate DC input
4-layer PCB with controlled impedance on Ethernet pairs
Functional blocks I want you to design:
CM4 socket: Raspberry Pi CM4102032 (2GB RAM, 32GB eMMC,
wireless). Standard dual 100-pin Hirose DF40 connectors.
PoE PD subsystem: Silvertel Ag9912 module accepting 48V
802.3at PoE+, providing 24V isolated output. Then a
TPS54331-based buck converter from 24V to 5V/3A for the CM4.
Ethernet front end: RJ45 magjack with separated PoE pairs
(Pulse JK0-0177NL or equivalent), routed to the CM4's MDI
pairs as 100Ω differential traces, length-matched.
Trusted Platform Module: Infineon SLB9672 TPM 2.0, SPI
interface to CM4 SPI0, 3.3V supply, with proper decoupling.
Real-time clock: Maxim DS3231SN on I2C bus, with CR1220
coin-cell battery backup for timekeeping during power loss.
Stepper motor drivers: 3× Trinamic TMC2209, one per axis
(X, Y, Z) driving NEMA 11 bipolar steppers at 0.67A/phase.
STEP and DIR from individual CM4 GPIOs, UART shared across
the three drivers for diagnostics, motor supply 24V.
Reset button: momentary pushbutton connected to the CM4
GLOBAL_EN pin with proper debouncing.
Camera interface: standard 22-pin CSI ribbon connector for
the Raspberry Pi HQ Camera (IMX477).
Debug: USB 2.0 micro for rpiboot programming, plus a
3-pin UART header for serial console.
Motor output connectors: 3× JST-XH 4-pin for stepper coils.
Protection: TVS diodes on Ethernet differential pairs and
on the 24V rail input.
Please start by generating a block diagram of the architecture
and confirming the topology before placing any components.
Once we agree on the architecture, we'll go block by block.
General Purpose Thick Film Standard Power
and High-Power Chip Resistor
47 kOhms ±5% 0.125W, 1/8W Chip Resistor 0805 (2012 Metric) Automotive AEC-Q200 Thick Film
Features:
- RMCF – standard power ratings
- RMCP – high power ratings
- Nickel barrier terminations standard
- Power derating from 100% at 70ºC to zero at +155ºC
- RoHS compliant, REACH compliant, and halogen free
- AEC-Q200 compliant
A momentary or non-latching switch which causes a temporary change in the state of an electrical circuit only while the switch is physically actuated. SWITCH TACTILE SPST-NO 0.05A 24V
An electrical connector acting as reusable interface to a conductor and creating a point where external circuits can be connected.
CM4 CM5 PoE Vision Signing Carrier
Industrial Raspberry Pi CM4/CM5-compatible carrier for PoE-powered inspection image capture and cryptographic signing with TPM, RTC, CSI camera, Ethernet, and three TMC2209 stepper axes.
Layout Rules
mm
Yes
10mm
Top
deg
Properties
Properties describe core aspects of the project.
Pricing & Availability
Distributor
Qty 1
Arrow
$26.42–$37.67
Digi-Key
$27.69–$32.31
HQonline
$7.10–$8.38
LCSC
$99.15–$101.55
Mouser
$52.88–$53.10
TME
$6.74
Verical
$24.05–$140.88
Controls
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