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Table of Contents
Instrument cluster — board teardown & chip map
A look inside the U5 instrument cluster (the IP module, board marked MAS861 EXCITE, hardware 861921104, built 2022-05). It is a small embedded-Linux computer: an NXP i.MX6 application processor driving the dashboard panels, with a companion safety MCU for the warning lamps. Photos and chip identification below.
The main chips
| Ref | Part | What it is / does |
|---|---|---|
| U100 | NXP i.MX6 Dual (``MCIMX6D6AVT08AD``) | The main processor — two Arm Cortex-A9 cores at 800 MHz, automotive grade. Runs the Linux UI and draws all the gauges, drive-mode artwork and start-up animation. |
| U500 | NXP MMPF0100 (PMIC) | Power-management IC. Generates every voltage rail the i.MX6 needs from the board's supply. |
| U300 (+ U301) | ISSI ``IS46TR16128C`` DDR3 SDRAM | The processor's working memory (DDR3). Two devices for a 32-bit bus. |
| U401 | TI ``DS90UB940A`` FPD-Link III deserializer | The single coax (FAKRA) link to the head unit. The head unit sends the cluster the reverse/backup-camera video over it (shown on the cluster when you select reverse — handled by ``libmas861video.so`` on ``/dev/video0``), and the same link is the bidirectional data + firmware-update back-channel to the head unit. |
| U900, U902 | TI/National ``DS90CF386`` LVDS receivers (two of them) | Convert the LVDS display signal into the parallel RGB that drives the two LCD panels (left “trip data” and the centre speedometer). |
| U804 (pair) | NXP ``TJA1044`` CAN transceivers | The physical interface to the vehicle CAN bus. Everything the cluster shows (speed, gear, lamps) arrives as CAN messages through these. Paired with EPCOS B82793 common-mode chokes. |
| companion MCU | NXP S12 / HCS12 | Separate safety microcontroller that drives the legally-mandated warning lamps. Deliberately independent of Linux, so the tell-tales keep working even if the UI hangs. |
| UGSP3708 | buzzer | The chime/gong speaker for the warning sounds. |
Also on the board: a 20-pin debug header, a USB port, the FAKRA coax for the FPD-Link video, the blue 32-way vehicle connector (power, ignition, Infotainment CAN), and the display ribbon (FFC) connectors.
Photos
U100 — NXP i.MX6 Dual (the processor)
U500 — NXP MMPF0100 (power management)
U300 — ISSI DDR3 memory
U401 — TI DS90UB940A (FPD-Link III: reverse-camera + head-unit back-channel)
U900 / U902 — TI DS90CF386 (LVDS display receivers)
U804 — NXP TJA1044 (CAN transceiver)
How it all connects
- Vehicle CAN → TJA1044 (U804) → i.MX6 (U100): the cluster reads speed, gear, state-of-charge and the lamp requests off the bus and renders them. It cannot be driven by the head unit directly.
- i.MX6 → LVDS → DS90CF386 (U900/U902) → the two dashboard LCD panels.
- Head unit → coax (FPD-Link III) → DS90UB940A (U401): the reverse-camera image, plus the data/firmware back-channel. (The right “media” strip itself is drawn locally by the i.MX6, not fed from here.)
- MMPF0100 (U500) powers the i.MX6; the S12 MCU independently holds the safety tell-tales.
Photos and identification from a bench teardown of a spare unit. Chip markings read directly from the dies; the S12 MCU is identified from the firmware, not pinpointed in these photos.