Pomera DM30 U-Boot

Pomera DM30 U-Boot source version 0.30 and i.MX Bootlets from King Jim CO., LTD.

The DM30 is a compact digital memo pad (digital typewriter) built around the Freescale (NXP) i.MX233 SoC with an E-Paper display.

Hardware Overview

Component	Detail
SoC	Freescale i.MX233 (MX23)
CPU	ARM926EJS @ 120 MHz
RAM	128 MB mDDR (2 x 64 MB banks, 0x40000000-0x47FFFFFF)
Display	800 x 600 E-Paper via IT8951 controller (I80 16-bit parallel)
Main Storage	eMMC (8-bit, mmc dev 1)
External Storage	SD card via SSP1 (mmc dev 0)
Keyboard	TX35894XBD matrix scanner via I2C
Serial	STMP3XXX Debug UART @ 115200 baud
Battery	Dry cell with LRADC voltage detection

Repository Structure

DM30_uboot/
├── u-boot/              # U-Boot source tree (version 0.30)
├── imx-bootlets/        # i.MX Bootlets for boot image packaging
├── build_dm30_uboot.sh  # Build script (macOS + arm-none-eabi-gcc 15)
├── README.md
└── LICENSE              # GNU GPL v2

Build

Prerequisites:

brew install arm-none-eabi-gcc arm-none-eabi-binutils

elftosb is required for the final .sb boot stream packaging:

git clone https://github.com/digdog/elftosb.git ../elftosb
cd ../elftosb && mkdir -p bld/macos
make -C bld/macos -f $(pwd)/makefile.rules SRC_DIR=$(pwd) UNAMES=Linux elftosb

Build U-Boot + Bootlets + .sb boot stream:

./build_dm30_uboot.sh

The script compiles U-Boot, bootlets (power_prep + boot_prep), and packages them into dm30-uboot.raw via elftosb.

Boot Flow

1. i.MX233 ROM loads power_prep and boot_prep from the .sb boot stream
2. boot_prep initializes DDR, clocks, and loads U-Boot
3. U-Boot initializes hardware (GPIO keys, eMMC, SD, LCD power, IT8951 E-Paper)
4. Checks for firmware update key combo (Right Ctrl + Right Shift); if pressed, enters update mode
5. Detects battery voltage via LRADC; powers off if too low (threshold ~2.4V / AD 15250)
6. Loads user program from eMMC User Program partition to DDR at 0x40000000
7. Jumps to user program with version info (0xdead << 16 | version << 8 | patchlevel)

Firmware Update

Triggered by holding Right Ctrl + Right Shift (GPIO) or C + 8 (I2C keyboard) during power-on. Requires USB 5V power.

1. Reads dm30-uboot.raw from SD card and writes to eMMC Bootloader partition
2. Reads Pomera_Update_Dm30_V*.bin from SD card
3. Validates series identifier ("DM30"), version, and checksum
4. Writes User Program and Database to eMMC with read-back verification

eMMC Storage Layout

Offsets are relative to the start of the first MBR partition.

Partition	Size
Bootloader	~8 MB
User Program	16 MB
Database	177 MB
Reserve	55 MB
Filesystem1	512 MB
Filesystem2	7556 MB

DDR Memory Map

Region	Address	Size
User Program	0x40000000	8 MB
Database	0x40800000	40 MB
Heap	0x43000000	80 MB

DM30-Specific Source Files

Board configuration

• u-boot/include/configs/dm30.h

Board initialization, eMMC and SD card pin setup

• u-boot/board/freescale/mx23_evk/mx23_evk.c

Core DM30 logic: boot flow, firmware update, battery detection, power management

• u-boot/common/dm30.c

IT8951 E-Paper display driver (I80 parallel interface, LCDIF DMA)

• u-boot/drivers/video/mxs/dm30.c
• u-boot/drivers/video/mxs/it8951_i80.c
• u-boot/drivers/video/mxs/it8951_i80.h

LCDIF hardware abstraction

• u-boot/drivers/video/mxs/lcdif.h
• u-boot/drivers/video/mxs/lcdif.c
• u-boot/drivers/video/mxs/mxsfb.c

LCD clock configuration

• u-boot/cpu/arm926ejs/mx23/mx23_lcd_clk.c

TX35894XBD I2C keyboard driver

• u-boot/drivers/input/dm30_keyb.c

MMC/SD driver with DMA

• u-boot/drivers/mmc/imx_ssp_mmc.c
• u-boot/drivers/mmc/mx23_mmc_dma.c
• u-boot/drivers/mmc/mxs-mmc.c

I2C driver

• u-boot/drivers/i2c/mxs_i2c.c

DMA driver

• u-boot/cpu/arm926ejs/mx23/mxs-dma.h
• u-boot/cpu/arm926ejs/mx23/mxs-dma.c

MXS reset block utility

• u-boot/include/asm-arm/arch-mx23/mxs-block.h

Version History

v0.30 (current) — Major hardware revision for DM30 production model

• Rebranded from DM100 to DM30 throughout codebase
• Replaced Ortus TFT LCD with IT8951 E-Paper controller via I80 parallel interface
• Migrated primary storage from NAND Flash to eMMC
• Added TX35894XBD I2C matrix keyboard driver with full QWERTY scancode table
• Added eMMC 8-bit bus support via GPMI pin FUN3 muxing
• Reworked firmware update to write from SD card to eMMC with read-back verification
• Added Right Ctrl GPIO key for firmware update trigger

v0.17 — Initial DM100-based bootloader

• Original code by smmei (2011)
• Ortus TFT LCD panel driver
• NAND Flash based storage
• GPIO-only key detection

Authors

• smmei (blog) — Original DM100/DM30 bootloader, power management, NAND/eMMC logic (2011)
• Zhong Yuan Huan — IT8951 E-Paper I80 driver (2017)
• cyliang — Right Ctrl key support (2017)

License

Distributed under the terms of version 2 of the GNU General Public License as published by the Free Software Foundation.