Difference between revisions of "Bticino F454"

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(Add info about suspected SPI EEPROM ...)
(Note U-Boot binary size.)
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|4159 / 2079.5 KiB
|4159 / 2079.5 KiB
|U-Boot binary at 0x00e00; U-Boot environment at offset 0x5ee00, size 0x1000
|U-Boot binary at 0x00e00, size 0x028270<br>U-Boot environment at offset 0x5ee00, size 0x01000

Revision as of 20:35, 7 December 2014

This page shall be a container for various pieces of information about Bticion's F454. Most of the information is - for now - derived from just poking around on the device with SSH. So, due to this and in general: of course certain details can be unsure or not accurate, because something has been overlooked.

The F454 is a typical embedded system using a SoC and running a Linux-based system.


The F454 is based on TI's (Texas Instruments) DaVinci DM365 SoC, from 2009. The Wikipedia page Texas Instruments DaVinci can be used as a first overview.


The SoC does include, among many peripherals, an ARM processor:

  • family: ARM9E
  • architecture: ARMv5TEJ
  • core: ARM926EJ-S

Apparently DM365 SoCs can run with 216 MHz, 270 MHz or 300 MHz.

A look at Linux' /proc/cpuinfo confirms:

root@basi:~# cat /proc/cpuinfo 
Processor	: ARM926EJ-S rev 5 (v5l)
BogoMIPS	: 134.34
Features	: swp half thumb fastmult edsp java 
CPU implementer	: 0x41
CPU architecture: 5TEJ
CPU variant	: 0x0
CPU part	: 0x926
CPU revision	: 5

Hardware	: BTicino BASI board
Revision	: 0000
Serial		: 0000000000000000

The system includes a device called bt_nexmed_hwmon.0. It is registered as a Linux hardware monitoring device and provides further information.

root@basi:~# cd /sys/devices/platform/bt_nexmed_hwmon.0
root@basi:/sys/devices/platform/bt_nexmed_hwmon.0# ls in* temp*
in1_input    in1_label    in2_input    in2_label    in4_input
in4_label    in5_input    in5_label    temp1_input  temp1_label
input label typical value comment
in1 Hw version 0
in2 board identification BASI BOARD
in4 cpu speed 270MHz
in5 board configuration 4 unknown - what does it mean?
temp1 Temperature 38 most likely in celcius?


/proc/meminfo lets us assume the SoC is equipped with most likely >102 MB of RAM:

root@basi:/sys/devices/virtual/gpio# cat /proc/meminfo | head -n 1
MemTotal:         103968 kB

Obviously there is no such thing as a 103968 kiB RAM chip. A kernel commandline found within the U-Boot environment suggests that there are 128MiB of RAM. The assumption is that the rest of the RAM, up to 128MiB, is associated with the DM365's HDVICP1 co-processor - instead of being under Linux' control.

The HDVICP1 is a 720p H264 encoder and decoder included in the DaVinci DM365 SoC. Altogether the DM365 SoC seems to be the most equipped DaVinci SoCs of it's series and time (2008/2009).

Question: Why DM365 - why does the F454 need this 720p en/decoding capability. Wouldn't a DM355 also do it? Related to video door entry systems?



The F454 includes a eMMC as non-volatile storage. It's size is 1,872 MiB (sector size: 512 byte) and is divided into essentially 6 paritions, using MBR style:

partition start sector size in sectors / in KiB usage
1 1 4159 / 2079.5 KiB U-Boot binary at 0x00e00, size 0x028270
U-Boot environment at offset 0x5ee00, size 0x01000
2 4160 20544 / 10,272 KiB ext3, comprises recovery Linux kernel uImage
3 24704 409664 / 204,832 KiB ext3, recovery root filesystem, mounted read-only
5 434369 20543 / 10,271.5 KiB ext3, comprises normal Linux kernel uImage
6 454913 409663 / 204,831.5 KiB ext3, normal root filesystem, mounted read-only
7 864592 2969264 / 1,484,632 KiB ext3, mounted on /home/bticino/cfg/extra, mounted read-write

Note that the U-Boot binary is at absolute offset 0x200 + 0xe00 = 0x1000.


For booting the F454 there is most likely an EEPROM. It is attached to interface SPI0 of the DM365. The used Linux kernel source suggests that it as a at25640, 64K bits in size. However that seems to be a bit small. More likely is something like 256K (TODO: see section software).

After power-on the DM365's ARM ROM boot loader (RBL) searches for its user boot loader (UBL). It does so via a pre-determined interface. The current assumption is that this interface is SPI. Other possibilities are for example NAND, MMC/SD, UART, ...

In case of the F454 the only other possibility would be MMC, but on the eMMC there does not seem to be the correct magic number (0xA1ACEDxx) within the first 24 blocks. So it has to be an SPI EEPROM - for booting.

Further information

The following talk by Raffaele Recalcati on FOSDEM 2011 provides some more details: DaVinci dm365 for home automation Video Slides (English). However it does not explicitly mention the F454. It includes background information, development history and even block diagrams. From the same author there is a presentation from 2012 called Linux in Bticino (Italian). It apparently includes more of Bticino's history in home automation and even something on the userspace application stack.

TODO: more


Tool Chain

Operating System