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Edge EInk Development Guide

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Alex J Lennon edited this page Oct 9, 2025 · 5 revisions

imx93-jaguar-eink Board Context

GitHub: Edge EInk Milestone

Hardware

  • SoC: i.MX93, Wireless: ublox MAYA W2 (IW612), Power: MCXC143VFM
  • Features: WiFi 6, BT 5.4, 802.15.4, LTE modem, 13" E-ink display
  • Security: EdgeLock Enclave (ELE) enabled for secure functionality, Cortex-M33 enabled for co-processing
  • Power Management: eink-power-cli utility for MCXC143VFM control

Pin Mapping ✅

  • WiFi SDIO: USDHC2 (SD2_CLK/CMD/DATA[0-3]), IRQ: GPIO4_IO25, RST: GPIO4_IO26
  • 802.15.4 SPI: LPSPI3 (GPIO_IO08-11), IRQ: GPIO4_IO27, RST: GPIO4_IO24 ✅ CONFIGURED
  • Bluetooth UART: LPUART5 (DAP_TDO/TDI/TCLK/TMS pins)
  • Power MCU UART: LPUART7 (/dev/ttyLP2) for MCXC143VFM communication

Key Files ✅

  • DT: lmp-device-tree/imx93-jaguar-eink.dts - Complete rewrite for MAYA W2
  • Kernel: linux-lmp-fslc-imx/imx93-jaguar-eink/*.cfg - WiFi/BT/802.15.4/LTE configs
  • Critical: fix_soc_imx9.cfg - Configures ELE for proper operation
  • Optimized: Minimal USB/display drivers for fast boot
  • Testing: Testing-And-Validation - Hardware validation procedures for E-Ink display interfaces
  • E-Ink Driver: eink-spectra6 recipe with corrected chip select routing implementation

WiFi Firmware Config ✅

  • Production: NXP_WIFI_SECURE_FIRMWARE="1" → .se files (secure)
  • Development: NXP_WIFI_SECURE_FIRMWARE="0" → .bin files (standard)
  • KAS Local: Set to "0" in kas/lmp-dynamicdevices.yml (no production impact)

WiFi Fixes ✅

  • Firmware Loading: Fixed signed builds with explicit fw_name module parameter
  • Reboot Stability: Fixed GPIO4_26 conflict, removed regulator GPIO control
  • Interface Management: mlan0 kept down by default, uap0 ignored by NetworkManager

Bluetooth Fixes ✅

  • UART Configuration: Fixed incorrect &lpuart4 → &lpuart5 assignment (commit fdbb5b2)
  • Hardware RTS/CTS: Hardware pinout issue resolved, device tree pinout verified correct
  • Pin Mapping: All DAP pins correctly mapped to LPUART5 (TX/RX/CTS/RTS)
  • Reset Control: BT_RST on GPIO4_IO24 managed by MCXC143VFM power controller

Hostname Generation ✅

  • Solution: Uses Foundries lmp-auto-hostname service (built-in)
  • Source: /sys/devices/soc0/serial_number via OCOTP/NVMEM
  • Format: imx93-jaguar-eink-{uid}

U-Boot Config ✅

  • Files: u-boot-fio/imx93-jaguar-eink/*.cfg (SPI, I2C, custom DTB)
  • Fix: disable-fiovb.cfg prevents boot command error

E-Ink Display Integration ✅

Hardware Architecture

  • Display: EL133UF1 13.3" E-Ink with dual controllers (left/right)
  • SPI Interface: LPSPI1 (/dev/spidev0.0) at 10 MHz
  • Chip Select Routing: Single CS line + L/R select GPIO for controller routing
  • GPIO Mapping: Reset=558, Busy=561, DC=559, L/R=560, Power=555 (GPIO2 base=544)

Software Implementation ✅ FIXED

  • Driver: eink-spectra6 recipe with corrected chip select routing
  • Routing Logic: L/R select GPIO set before CS activation
  • Sequential Access: Controllers accessed one at a time (not simultaneously)
  • Hardware Match: Software now correctly implements hardware design

Key Changes Applied

  1. Fixed CS Routing: Single CS + L/R routing instead of dual independent CS
  2. Correct GPIO Numbers: Updated for i.MX93 GPIO2 base address (544)
  3. Sequential Operation: L/R select → CS activate → SPI transfer → CS deactivate
  4. Backward Compatibility: Existing API maintained for applications

Testing Commands ✅ VALIDATED

Last Tested: 2025-01-09 on imx93-jaguar-eink (kernel 6.6.52)
Status: ✅ Software validated, ready for hardware connection

E-Ink Demo Application ✅

# Demo application (software validated, ready for hardware)
sudo el133uf1_demo -d /dev/spidev0.0 -r 558 -b 561 -0 559 -1 560 white
sudo el133uf1_demo -d /dev/spidev0.0 -r 558 -b 561 -0 559 -1 560 colorbar

# Automated testing script
./scripts/test-eink-demo-target.sh

E-Ink Test Application ✅

# Test E-Ink with corrected GPIO numbers (software validated)
sudo el133uf1_test -d /dev/spidev0.0 -r 558 -b 561 -0 559 -1 560 --test-spi

# Board configuration info
el133uf1_test --board-info

802.15.4 SPI Interface

# Test 802.15.4 SPI interface
ls -la /dev/spidev2.0
echo -n -e '\x55' | spi-pipe -d /dev/spidev2.0 -s 1000000 -b 8

802.15.4 Interface ✅ CONFIGURED

Hardware Configuration

  • SPI Interface: LPSPI3 (/dev/spidev2.0) at 12 MHz
  • Pin Mapping: GPIO_IO08 (CS), GPIO_IO09 (MOSI), GPIO_IO10 (MISO), GPIO_IO11 (SCK)
  • Interrupt: GPIO4_IO27 (ENET2_RD3) - ZB_INT signal
  • Reset: Shared with Bluetooth (GPIO4_IO24, controlled by MCXC143VFM)

Software Implementation ✅ ADDED

  • Device Tree: LPSPI3 configured with proper pinctrl settings
  • SPI Device: /dev/spidev2.0 available for 802.15.4 communication
  • IW612 Support: ublox MAYA W2 module provides 802.15.4 functionality
  • Kernel Config: 802.15.4 subsystem enabled in kernel configuration

Status ✅

  • Build: SUCCESS (complete with 4GB partition support)
  • Boot: SUCCESS (automatic device tree loading fixed)
  • WiFi: WORKING (firmware loading, reboot stability fixed)
  • Hostname: WORKING (OCOTP + lmp-auto-hostname)
  • EdgeLock Enclave: WORKING (secure functionality confirmed)
  • Cortex-M33: ENABLED (remoteproc and RPMSG support configured)
  • Partition Size: FIXED (4GB root partition prevents image overflow)

Boot Fixes ✅

  • U-Boot DTB: Added missing 01-customise-dtb.patch to set fdt_file=imx93-jaguar-eink.dtb
  • Boot Script: Explicit fdt_file setting in boot.cmd for reliable device tree loading
  • Partition Size: Custom WIC file imx93-jaguar-eink-large.wks with 4GB root partition
  • Image Size: IMAGE_ROOTFS_EXTRA_SPACE increased to prevent "Image too large" errors

EdgeLock Enclave & Cortex-M33 Configuration ✅

  • ELE Memory Region: ele_reserved@90000000 (1MB) for secure enclave operations
  • M33 Memory Regions: Resource table, vring buffers, and 16MB non-cacheable section
  • Device Tree: s4muap enabled for ELE Message Unit, imx93_cm33 configured for remoteproc
  • Kernel Config: fix_soc_imx9.cfg enables ELE support, enable_m33_support.cfg adds remoteproc/RPMSG
  • Communication: RPMSG framework for inter-processor communication with M33 core

TODO: Dynamic Partition Sizing

  • GitHub Issue: #20
  • Optimization: Replace fixed 4GB partition with calculated size + auto-resize on boot
  • Benefits: Smaller image files, faster flashing, automatic expansion to available space
  • Implementation: Use systemd-growfs or similar to expand root partition on first boot
  • WIC Enhancement: Calculate minimum required size based on actual rootfs content

Implementation Notes

  • Wireless: IW612 MOAL/MLAN drivers, 802.15.4 subsystem, BT UART HCI
  • Power: MCXC143VFM controller, fixed regulators, shared BT/ZB reset
  • Removed: Audio, camera, HDMI/DSI, dual ethernet, extra USB
  • Security: EdgeLock Enclave enabled and functional for secure operations
  • Security: EdgeLock Enclave (ELE) enabled for secure functionality, Cortex-M33 disabled, ELE-based OCOTP for fuse access

Fixed Issues ✅

  • Machine config syntax, module autoloading, ZigBee support
  • U-Boot fdt_file approach, kernel panic (ELE), device tree compilation
  • U-Boot fiovb error, WiFi firmware loading, GPIO conflicts

Build Commands

export KAS_MACHINE=imx93-jaguar-eink
./kas-build-base.sh

Key Paths

  • DT: lmp-device-tree/imx93-jaguar-eink.dts
  • Machine: conf/machine/imx93-jaguar-eink.conf
  • Kernel: linux-lmp-fslc-imx/imx93-jaguar-eink/*.cfg
  • Images: build/tmp/deploy/images/imx93-jaguar-eink/

Recent Fixes (2025-08-29) ✅

OCOTP Patch Issue

  • Problem: 01-add-imx93-ocotp-support.patch failed (kernel version mismatch)
  • Solution: Removed patch, use existing kernel OCOTP drivers + config
  • Result: ELE support enabled via CONFIG_IMX_SEC_ENCLAVE=y, CONFIG_NVMEM_IMX_OCOTP_FSB_S400=y

WiFi Firmware Warning

  • Problem: KAS builds showed secure firmware warning
  • Solution: Set NXP_WIFI_SECURE_FIRMWARE="0" in kas/lmp-dynamicdevices.yml
  • Result: Local builds use .bin files, production unaffected

Key Learnings

  • Prefer kernel config over custom patches
  • KAS config only affects local development builds

SSH Testing Setup ✅

For automated testing and deployment to target boards, proper SSH configuration is essential:

Required Setup Steps

  1. Use fio user: All SSH connections should use the fio user account
  2. Copy SSH public key: Enable passwordless authentication
  3. Configure passwordless sudo: Allow fio user to run commands without password prompts

Setup Commands

# Copy SSH public key to target board
echo "fio" | ssh-copy-id -f fio@192.168.0.36

# Configure passwordless sudo for fio user
ssh fio@192.168.0.36 "echo 'fio' | sudo -S sh -c 'echo \"fio ALL=(ALL) NOPASSWD: ALL\" > /etc/sudoers.d/fio'"

Benefits

  • Automated testing: Scripts can run without manual password entry
  • Faster development: No password prompts during iterative testing
  • CI/CD ready: Enables automated deployment and testing pipelines
  • Consistent workflow: Same setup across all target boards

Usage Example

# Deploy and test E-Ink application
scp el133uf1_test fio@192.168.0.36:/tmp/
ssh fio@192.168.0.36 "cd /tmp && chmod +x el133uf1_test && sudo ./el133uf1_test --test-spi"

Security Notes

  • SSH key authentication is more secure than password authentication
  • Passwordless sudo is acceptable for development/testing environments
  • Production deployments should use more restrictive sudo configurations

Power Management ✅ INTEGRATED

MCXC143VFM Power Controller

  • Communication: LPUART7 (/dev/ttyLP2) serial interface
  • CLI Tool: eink-power-cli / eink-pmu for power management
  • Auto-Install: Included in all imx93-jaguar-eink builds
  • Configuration: Optional /etc/eink-power-cli.toml

Power CLI Usage

# Check power status
eink-pmu status

# Battery monitoring
eink-pmu battery

# Power sequencing control
eink-power-cli --help

Integration Details

  • Recipe: recipes-devtools/eink-power-cli/eink-power-cli_git.bb
  • Source: github.com/DynamicDevices/eink-power-cli (Rust-based)
  • Machine Feature: el133uf1 enables power management features
  • Dependencies: Automatically resolved for MCXC143VFM communication

Cross-Compilation Requirements ⚠️

Critical: Development machine (x86_64) and target board (ARM64) have different architectures:

Architecture Details

  • Development Machine: x86_64 (Intel/AMD 64-bit)
  • Target Board: ARM64/AArch64 (i.MX93 processor)
  • Consequence: Binaries compiled on development machine WILL NOT RUN on target board

Correct Build Methods

  1. Yocto/KAS Build (Recommended):

    # Cross-compiles automatically for target architecture
export KAS_MACHINE=imx93-jaguar-eink
kas-container shell kas/lmp-dynamicdevices-base.yml -c "bitbake eink-spectra6"

# Copy ARM64 binary from Yocto build output
scp build/tmp/work/cortexa55-lmp-linux/eink-spectra6/*/image/usr/bin/el133uf1_test fio@192.168.0.36:/tmp/

  2. Cross-Compiler Toolchain (Alternative):

    # Use ARM64 cross-compiler (if available)
aarch64-linux-gnu-gcc -o el133uf1_test src/*.c

Common Mistake ❌

# This creates x86_64 binary that won't run on ARM64 target
cd /local/project/build && make
scp el133uf1_test fio@192.168.0.36:/tmp/  # ❌ Will fail with "cannot execute binary file"

Verification

# Check binary architecture before deployment
file el133uf1_test
# Should show: "ELF 64-bit LSB executable, ARM aarch64" (not x86-64)

Last Updated: 2025-01-09 Status: ✅ SSH TESTING SETUP DOCUMENTED - Added automated testing workflow for target board deployment

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