eCos Reference Manual
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# ARM/StrongARM(SA11X0) Bright Star Engineering commEngine and nanoEngine

## Overview

RedBoot supports a serial port and the built in ethernet port for communication and downloads. The default serial port settings are 38400,8,N,1. RedBoot runs from and supports flash management for the system flash region.

The following RedBoot configurations are supported:

Configuration | Mode | Description | File
--- | --- | --- | ---
POST | [ROM] | RedBoot running from the first free flash block at 0x40000. | redboot_ROM.ecm
RAM | [RAM] | RedBoot running from RAM with RedBoot in the flash boot sector. | redboot_RAM.ecm

## Initial Installation

Unlike other targets, the nanoEngine comes equipped with boot firmware which you cannot modify. See chapter 5, "nanoEngine Firmware" of the nanoEngine Hardware Reference Manual (we refer to "July 17, 2000 Rev 0.6") from Bright Star Engineering.

Because of this, eCos, and therefore Redboot, only supports a special configuration of the ROM mode, starting at offset 0x40000 in the flash.

Briefly, the POST-configuration RedBoot image lives in flash following the BSE firmware. The BSE firmware is configured, using its standard bootcmd command, to run RedBoot at startup.

## Download Instructions

You can perform the initial load of the POST-configuration RedBoot image into flash using the BSE firmware's load command. This will load a binary file, using TFTP, and program it into flash in one operation. Because no memory management is used in the BSE firmware, flash is mapped from address zero upwards, so the address for the RedBoot POST image is 0x40000. You must use the binary version of RedBoot for this, `redboot-post.bin`.

This assumes you have set up the other BSE firmware config parameters such that it can communicate over your network to your TFTP server.

    >load redboot-post.bin 40000
    loading ... erasing blk at 00040000
    erasing blk at 00050000
    94168 bytes loaded cksum 00008579
    done
    >
    > set bootcmd "go 40000"
    > get
    myip = 10.16.19.198
    netmask = 255.255.255.0
    eth = 0
    gateway = 10.16.19.66
    serverip = 10.16.19.66
    bootcmd = go 40000
    >

> NOTE: the BSE firmware runs its serial IO at 9600 Baud; RedBoot runs instead at 38400 Baud. You must select the right baud rate in your terminal program to be able to set up the BSE firmware.

After a reset, the BSE firmware will print

    Boot: BSE 2000 Sep 12 2000 14:00:30
    autoboot: "go 40000" [hit ESC to abort]

and then RedBoot starts, switching to 38400 Baud.

Once you have installed a bootable RedBoot in the system in this manner, we advise re-installing using the generic method described in Chapter 4 in order that the Flash Image System contains an appropriate description of the flash entries.

## Cohabiting with POST in Flash

The configuration file named `redboot_POST.ecm` configures RedBoot to build for execution at address 0x50040000 (or, during bootup, 0x00040000). This is to allow power-on self-test (POST) code or immutable firmware to live in the lower addresses of the flash and to run before RedBoot gets control. The assumption is that RedBoot will be entered at its base address in physical memory, that is 0x00040000.

Alternatively, for testing, you can call it in an already running system by using `go 0x50040040` at another RedBoot prompt, or a branch to that address. The address is where the reset vector points. It is reported by RedBoot's load command and listed by the fis list command, amongst other places.

Using the POST configuration enables a normal config option which causes linking and initialization against memory layout files called "...post..." rather than "...rom..." or "...ram..." in the `include/pkgconf` directory. Specifically:

`include/pkgconf/mlt_arm_sa11x0_nano_post.h`
`include/pkgconf/mlt_arm_sa11x0_nano_post.ldi`
`include/pkgconf/mlt_arm_sa11x0_nano_post.mlt`

It is these you should edit if you wish to move the execution address from 0x50040000 in the POST configuration. Startup mode naturally remains ROM in this configuration.

Because the nanoEngine contains immutable boot firmware at the start of flash, RedBoot for this target is configured to reserve that area in the Flash Image System, and to create by default an entry for the POST mode RedBoot.

    RedBoot> fis list
    Name              FLASH addr  Mem addr    Length      Entry point
    (reserved)        0x50000000  0x50000000  0x00040000  0x00000000
    RedBoot[post]     0x50040000  0x00100000  0x00020000  0x50040040
    RedBoot config    0x503E0000  0x503E0000  0x00010000  0x00000000
    FIS directory     0x503F0000  0x503F0000  0x00010000  0x00000000
    RedBoot>

The entry "(reserved)" ensures that the FIS cannot attempt to overwrite the BSE firmware, thus ensuring that the board remains bootable and recoverable even after installing a broken RedBoot image.

## Special RedBoot Commands

The nanoEngine/commEngine has one or two Intel i82559 Ethernet controllers installed, but these have no associated serial EEPROM in which to record their Ethernet Station Address (ESA, or MAC address). The BSE firmware records an ESA for the device it uses, but this information is not available to RedBoot; we cannot share it.

To keep the ESAs for the two ethernet interfaces, two new items of RedBoot configuration data are introduced. You can list them with the RedBoot command fconfig -l thus:

    RedBoot> fconfig -l
    Run script at boot: false
    Use BOOTP for network configuration: false
    Local IP address: 10.16.19.91
    Default server IP address: 10.16.19.66
    Network hardware address [MAC] for eth0: 0x00:0xB5:0xE0:0xB5:0xE0:0x99
    Network hardware address [MAC] for eth1: 0x00:0xB5:0xE0:0xB5:0xE0:0x9A
    GDB connection port: 9000
    Network debug at boot time: false
    RedBoot>

You should set them before running RedBoot or eCos applications with the board connected to a network. The fconfig command can be used as for any configuration data item; the entire ESA is entered in one line.

## Memory Maps

The first level page table is located at physical address 0xc0004000. No second level tables are used.

> NOTE: The virtual memory maps in this section use a C and B column to indicate whether or not the region is cached (C) or buffered (B).

    Physical Address Range     Description
    -----------------------    ----------------------------------
    0x00000000 - 0x003fffff    4Mb FLASH (nCS0)
    0x18000000 - 0x18ffffff    Internal PCI bus - 2 x i82559 ethernet
    0x40000000 - 0x4fffffff    External IO or PCI bus
    0x80000000 - 0xbfffffff    SA-1110 Internal Registers
    0xc0000000 - 0xc7ffffff    DRAM Bank 0 - 32Mb SDRAM
    0xc8000000 - 0xcfffffff    DRAM Bank 1 - empty
    0xe0000000 - 0xe7ffffff    Cache Clean

    Virtual Address Range    C B  Description
    -----------------------  - -  ----------------------------------
    0x00000000 - 0x001fffff  Y Y  DRAM - 8Mb to 32Mb
    0x18000000 - 0x180fffff  N N  Internal PCI bus - 2 x i82559 ethernet
    0x40000000 - 0x4fffffff  N N  External IO or PCI bus
    0x50000000 - 0x51ffffff  Y Y  Up to 32Mb FLASH (nCS0)
    0x80000000 - 0xbfffffff  N N  SA-1110 Internal Registers
    0xc0000000 - 0xc0ffffff  N Y  DRAM Bank 0: 8 or 16Mb
    0xc8000000 - 0xc8ffffff  N Y  DRAM Bank 1: 8 or 16Mb or absent
    0xe0000000 - 0xe7ffffff  Y Y  Cache Clean

The ethernet devices use a "PCI window" to communicate with the CPU. This is 1Mb of SDRAM which is shared with the ethernet devices that are on the PCI bus. It is neither cached nor buffered, to ensure that CPU and PCI accesses see correct data in the correct order. By default it is configured to be megabyte number 30, at addresses 0x01e00000-0x01efffff. This can be modified, and indeed must be, if less than 32Mb of SDRAM is installed, via the memory layout tool, or by moving the section `__pci_window` referred to by symbols `CYGMEM_SECTION_pci_window*` in the linker script.

Though the nanoEngine ships with 32Mb of SDRAM all attached to DRAM bank 0, the code can cope with any of these combinations also; "2 x " in this context means one device in each DRAM Bank.

1 x 8Mb = 8Mb 2 x 8Mb = 16Mb
1 x 16Mb = 16Mb 2 x 16Mb = 32Mb

All are programmed the same in the memory controller.

Startup code detects which is fitted and programs the memory map accordingly. If the device(s) is 8Mb, then there are gaps in the physical memory map, because a high order address bit is not connected. The gaps are the higher 2Mb out of every 4Mb.

The SA11x0 OS timer is used as a polled timer to provide timeout support within RedBoot.

## Nano Platform Port

The nano is in the set of SA11X0-based platforms. It uses the arm architectural HAL, the sa11x0 variant HAL, plus the nano platform hal. These are components

CYGPKG_HAL_ARM hal/arm/arch/
CYGPKG_HAL_ARM_SA11X0 hal/arm/sa11x0/var
CYGPKG_HAL_ARM_SA11X0_NANO hal/arm/sa11x0/nano

respectively.

The target name is "nano" which includes all these, plus the ethernet driver packages, flash driver, and so on.

## Ethernet Driver

The ethernet driver is in two parts:

A generic ether driver for Intel i8255x series devices, specifically the i82559, is `devs/eth/intel/i82559`. Its package name is `CYGPKG_DEVS_ETH_INTEL_I82559`.

The platform-specific ether driver is `devs/eth/arm/nano`. Its package is `CYGPKG_DEVS_ETH_ARM_NANO`. This tells the generic driver the address in IO memory of the chip, for example, and other configuration details. This driver picks up the ESA from RedBoot's configuration data - unless configured to use a static ESA in the usual manner.

## Rebuilding RedBoot

These shell variables provide the platform-specific information needed for building RedBoot according to the procedure described in Chapter 3:

    export TARGET=nano
    export ARCH_DIR=arm
    export PLATFORM_DIR=sa11x0/nano

The names of configuration files are listed above with the description of the associated modes.

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