NEC DDB-VRC4375

Overview

RedBoot supports only serial port 1, which is connected to the upper of the stacked serial connectors on the board. The default serial port settings are 38400,8,N,1. FLASH management is also supported. Two basic RedBoot configurations are supported:

Since the normal RedBoot configuration does not use the FLASH ROM except during startup, it is unnecessary to load a RAM-based RedBoot before reprogramming the FLASH.

Initial Installation Method

A device programmer should be used to program a socketed FLASH part (AMD 29F040). The board as delivered is configured for a 512K EPROM. To install a FLASH ROM, Jumpers J30, J31 and J36 need to be changed as described in the board's User Manual.

Since RedBoot for this board relocates itself from ROM to RAM at startup, it is not necessary to run a secondary RAM based version of RedBoot to update the main FLASH image. Instead this can be done from the primary version of RedBoot.

Updating the primary RedBoot image

To update the primary RedBoot image, follow the procedures detailed in the Section called Update the primary RedBoot flash image in Chapter 4, but the actual numbers used with the flags in the sample commands should be:
-b 0x80100000
Flash locking and unlocking is not required. Note that these values are inferred when updating the RedBoot image once the fis create has been run.

Special RedBoot Commands

None.

Memory Maps

RedBoot sets up the memory map primarily as described in the board's User Manual. There are some minor differences, noted in the following table:
Physical                Virtual                 Resource
Addresses               Addresses
00000000-01FFFFFF       80000000-81FFFFFF       Base SDRAM (cached)
00000000-01FFFFFF       A0000000-A1FFFFFF       Base SDRAM (uncached)
0C000000-0C0BFFFF       AC000000-AC0B0000       PCI IO space
0F000000-0F0001FF       AF000000-AF0001FF       VRC4375 Registers
1C000000-1C0FFFFF       BC000000-BC0FFFFF       VRC4372 Registers
1C100000-1DFFFFFF       BC100000-BDFFFFFF       PCI Memory space
1FC00000-1FC7FFFF       BFC00000-BFC7FFFF       FLASH ROM
80000000-8000000D       C0000000-C000000D       RTC
8000000E-80007FFF       C000000E-C0007FFF       NVRAM
81000000-81FFFFFF       C1000000-C1FFFFFF       Z85C30 DUART
82000000-82FFFFFF       C2000000-C2FFFFFF       Z8536 Timer
83000000-83FFFFFF       C3000000-C3FFFFFF       8255 Parallel port
87000000-87FFFFFF       C7000000-C7FFFFFF       Seven segment display

Resource Usage

The RedBoot image occupies flash addresses 0x1fc00000 - 0x1fc1ffff. To execute it copies itself out of there to RAM at 0x80000000. RedBoot reserves 1MB of RAM from 0x80000000 to 0x800FFFFF for its own use. The top 1MB of RAM from 0x81F00000 to 0x81FFFFFF is reserved for use by the PCI Ethernet device. RAM based RedBoot configurations are designed to run from RAM at virtual addresses 0x80100000 - 0x8011ffff. RAM virtual addresses from 0x80020000 to the start of the PCI window are available for general use, such as a temporary scratchpad for downloaded images, before they are written to flash.

Ethernet Driver

The ethernet driver is in two parts:

A generic ether driver for the Intel i21143 device is located in devs/eth/intel/i21143. Its package name is CYGPKG_DEVS_ETH_INTEL_I21143.

The platform-specific ether driver is devs/eth/mips/vrc4375. Its package is CYGPKG_DEVS_ETH_MIPS_VRC4375. This tells the generic driver the address in IO memory of the chip, for example, and other configuration details. The ESA (MAC address) is by default collected from on-board serial EEPROM, unless configured statically within this package.

Rebuilding RedBoot

The instructions in Chapter 3 should be followed. The values for TARGET, ARCH_DIR and PLATFORM_DIR on this platform are “vrc4375”, “mips” and “vrc4375” respectively. The configuration export files supplied in the hal/mips/vrc4375/VERSION/misc directory in the RedBoot source tree should be used. In general only the ROMRAM variant should need to be used.