MIPI CSI-2 Camera Bring-up

Document

AN-003

Revision

0.2

Date

June 2026

Download PDFrev 0.2Latest revision

Scope

This application note covers bringing up a MIPI CSI-2 camera on the on-EVK CSI connector: configuring the on-module per-camera LDO, validating the lane routing, and reading the first frame through the SDK's <alp/camera.h> API.

Table: Scope summary

Field	Detail
Audience	Firmware engineers integrating a camera sensor into vision workloads.
Prerequisites	QS- guide completed, RPi-compatible MIPI camera module (e.g. RPi V2 or HQ camera).
Outcome	ai-camera-viewer running, streaming live frames to the display.
Time	20 minutes.
Source	examples/camera-vision/ai-camera-viewer/ in alp-sdk.

Hardware Setup

Table: MIPI CSI-2 camera support per family

SoM family	CSI interfaces + LDO
E1M-AEN	1 × 2-lane CSI (CSI0). On-die Alif Ensemble ISP-Pico (VeriSilicon ISP Nano Pico, DT compatible vsi,isp-pico) on E4 / E6 / E8 (not on E3 / E5 / E7). Per-camera LDO: +V_CAM0 (Z34) + CAM_VFB0 (Z33) divider.
E1M-X V2N / V2N-M1	2 × 4-lane CSI (CSI0, CSI1). On-module ISP. Per-camera LDOs: +V_CAM0…+V_CAM3 with matching CAM_VFBx feedback divider.

Place the feedback resistor pair (R1, R2) close to the SoM CAM_VFBx pin; long feedback traces invite oscillation. The output voltage is set by:

V_CAM = 0.6 V × (1 + R1 / R2)

Software Walkthrough

west build -b <BOARD> examples/camera-vision/ai-camera-viewer
west flash

The example brings up CSI0, energises the per-camera LDO, opens an OV5640 stream at 240 × 240 RGB565 via alp_camera_open(), and renders the live preview to the display.

Expected Output

[cam] LDO0 -> 2.8 V (target 2.8 V, divider 220k/82k)
[cam] CSI0 link up, 2 lanes @ TBD Mbps
[cam] streaming 240x240 RGB565 @ 30 fps

Troubleshooting

• LDO voltage off: divider current too low; reduce R1 + R2 until divider current = 100 × worst-case feedback-pin current (see DS-AEN-001 §7.8 formula).
• No CSI link: differential lanes swapped (P/N reversed) or trace impedance not 100 Ω differential.
• Lane skew errors: lane-to-lane length mismatch > TBD ps.

References

• Example source: examples/camera-vision/ai-camera-viewer/ in alp-sdk; API in include/alp/camera.h. Silicon bring-up reg-checks: examples/aen/aen-camera-regcheck/, examples/aen/aen-isp-regcheck/.
• Hardware Design Guides: HG-AEN-001 §5.5, HG-V2N-001 §6.4 (MIPI CSI-2 routing rules).
• Datasheet CSI-2 pin tables: §2.3 in each datasheet.

Revision History

Table: Revision History

Revision	Changes	Date
0.1	Initial draft.	May 2026
0.2	Updated SDK references to current layout: example path examples/camera-vision/ai-camera-viewer/, added include/alp/camera.h and the aen-camera-regcheck / aen-isp-regcheck reg-checks; corrected the AEN on-die ISP to the Alif Ensemble ISP-Pico (vsi,isp-pico); aligned the stream config with the example (240×240 RGB565).	June 2026