| Item | Requirement | |-------------------------|-----------------------------------------------------------------------------| | PCB flammability | UL 94V-0 (specified in fabrication notes, not schematic) | | CM4 connector | 200-pin DDR2 SODIMM, 0.6mm pitch, 94V0-rated housing | | Power sequencing | 3.3V must be stable before enabling CM4_EN (no strict sequence needed, but good practice) | | ESD protection | On all external I/O (USB, HDMI, Ethernet, GPIO) | | Decoupling caps | 100nF + 10µF per CM4 power pin pair (as per CM4 datasheet) | | Trace impedance | 90Ω (USB, HDMI, MIPI), 100Ω (Ethernet RGMII, PCIe), 50Ω (single-ended) |
: Traces for cameras (CSI) and displays (DSI) require careful length matching and continuous ground planes to maintain signal integrity. cm4 94v0 schematics
The CM4 exposes a GMAC (Gigabit Media Access Controller) for Ethernet. 100Ω (Ethernet RGMII