[En-Nut-Discussion] Robust Ethernet bootloader

Dušan dferbas at solarmonitor.cz
Tue Sep 11 10:59:19 CEST 2018 

Hi Philipp,

now, we are downloading new firmware onto SD card and then bootloader 
processes it from SD card during power up.

In the past, when we have no SD card, we used a TCP stack of the 
application and from http server, we were calling the bootloader to 
parse and flash firmware records.
The bootloader fits into 2kB and you can upgrade firmware through web.
Initially, there was a serial xmodem protocol on uart and
once an application was in board, it was accepting a byte stream with 
API calls from main application.
I.e. it was implemented in a following way (assembler is for 
ATmega128/1281, for 2561 it was done similarly, if you are interested, I 
can send you some files):

This was written in 2009, now we will write it more clearly with some LD 
script stuff to place code on expected addresses.

bootloader:
---------------
static void InituP(void) __attribute__ ((naked, section(".init1"), used));

void InituP(void)
{
     asm volatile ("clr    __zero_reg__");
     cli();
     asm volatile ("rjmp next");
     asm volatile ("jmp boot_loader_data_init");             //we assume 
this will be always at @ 0x1F806
     asm volatile ("jmp boot_loader_data_send");
     asm volatile ("next:");

application:
----------------
typedef void Tboot_loader_data_init(unsigned char *);
#define boot_loader_data_init ((Tboot_loader_data_init *)0x1F806)

typedef int Tboot_loader_data_send(unsigned char *, unsigned char *, 
unsigned short);
#define boot_loader_data_send ((Tboot_loader_data_send *)0x1F80A)

*Dusan Ferbas
*

On 5.6.2018 14:10, Philipp Burch wrote:
> Hi Gregor,
>
> thanks for the update. I've used U-Boot only with Linux kernels so far,
> good to know that it also supports bare-metal applications. I'll have a
> look at it.
>
> Regards,
> Philipp
>
> On 05.06.2018 12:59, Gregor Mackenzie wrote:
>> It's possible to configure u-boot to automatically execute Nut O/S programs
>> on power up. It can also handle tftp and other tcp/ip based transfers.
>> U-boot will also allow boot over tftp, so you could make your boards load
>> the application from your central server each time they start if you wish
>> too.
>>
>> I did a little experimentation with an Ethernut 5 board to this end a while
>> ago using the stock Ethernut 5 u-boot image and replacing the Linux image
>> with a Nut O/S executable.
>>
>> There are various tftp servers around. I think Harald's preferred one at
>> the time was tftp32.
>>
>> On Tue, 5 Jun 2018, 12:00 ,<en-nut-discussion-request at egnite.de>  wrote:
>>
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>>> Today's Topics:
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>>>     1. Robust Ethernet bootloader (Philipp Burch)
>>>
>>>
>>> ----------------------------------------------------------------------
>>>
>>> Message: 1
>>> Date: Mon, 4 Jun 2018 15:06:05 +0200
>>> From: Philipp Burch<phip at hb9etc.ch>
>>> To: "Ethernut User Chat (English)"<en-nut-discussion at egnite.de>
>>> Subject: [En-Nut-Discussion] Robust Ethernet bootloader
>>> Message-ID:<a0bebd81-2efe-ab8d-802a-b4852fdd49c0 at hb9etc.ch>
>>> Content-Type: text/plain; charset=utf-8
>>>
>>> Hi everyone,
>>>
>>> I'm in a project where we will soon have to deploy some boards running
>>> Nut/OS into "the field". Those boards are all connected to a local
>>> computer using Ethernet, but the computer itself is usually only
>>> accessible over the net. In the first prototype, we simply put a J-Link
>>> into the machine to be able to update the MCU firmware (or even debug
>>> it), in case a problem arises, but this definitely is no productive
>>> solution. We use Ethernet to have a robust and isolated connection after
>>> all, which USB and JTAG is not.
>>>
>>> Our target platform is a TIVA TM4C1294NCPDT processor, which has an
>>> integrated Ethernet MAC and PHY. My primary concern is robustness of the
>>> bootloader, it should be rather hard to brick the device. I see that
>>> there is some Ethernet-based bootloader functionality in the ROM of this
>>> MCU, but as far as I can tell, this must be invoked from the application
>>> code. So in case the update fails, there will most likely be no way to
>>> re-flash the firmware without local intervention. What I would prefer is
>>> a small self-contained bootloader that always runs when the firmware
>>> starts (after power-on, watchdog-reset, hard-fault, etc.), validates the
>>> firmware image and then starts the application. In case the validation
>>> fails, it should sit there and wait for a new image to be downloaded.
>>>
>>> My questions:
>>>
>>> - What are your experiences and suggestions for Ethernet bootloaders?
>>>
>>> - Did I miss anything important?
>>>
>>> - Does Nut/OS offer some functionality for this?
>>>
>>> - How do I need to compile the target application, so that it can be
>>> started from the bootloader? Especially considering the interrupt vector
>>> table and such stuff.
>>>
>>> Thank you and best regards,
>>> Philipp
>>>
>>>
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