Description

This document covers the configuration and usage of eCos and RedBoot on the Logic Zoom eXperimenter board. The board comes in two versions, one fitted with an TI OMAP L138 processor and the other with a TI Sitara AM1808 processor. The boards and processors are functionally identical as far as eCos and this documentation are concerned. To simplify the text below the board is generally referred to as the Zoom and where the text doesn't differentiate between the two processors, all references to the OMAP-L138 should be taken to refer to either processor. In addition, all OMAP-L138 specific processor configuration and target names referred to below the should also be used for the Sitara AM1808 prcoessor. The Zoom board consists of a base board and a CPU module. The CPU module containing either the OMAP L138 or Sitara AM1808 processors. The base board contains the CPU module, 64Mbytes of SDRAM, 8Mbytes of serial NOR flash memory on SPI0, a LAN87810A PHY, a MMC/SD socket, external connections for one serial channel, ethernet, USB host/device, and the various other peripherals supported by the CPUs. eCos support for the devices and peripherals on the board and the CPU is described below.

For typical eCos development, a RedBoot image is programmed into the SPI NOR flash memory, and the board will load this image from reset. RedBoot provides gdb stub functionality so it is then possible to download and debug stand-alone and eCos applications via the gdb debugger. This can happen over either a serial line or over ethernet.

This documentation is expected to be read in conjunction with the OMAP L1xx processor HAL documentation and further device support and subsystems are described and documented there.

Supported Hardware

The SPI NOR flash consists of 128 blocks of 64Ki bytes each. In a typical setup, the first block is reserved for the second-level bootstrap, the User Boot Loader. The following two blocks are reserved for the use of the ROM RedBoot image. The topmost block is used to manage the flash and the next block down holds RedBoot fconfig values. The remaining blocks can be used by application code.

Serial support is through the CYGPKG_IO_SERIAL_GENERIC_16X5X generic driver package which is modified by the CYGPKG_IO_SERIAL_ARM_OMAP_L1XX driver package for the OMAP L1xx. These packages can support all the serial devices on the OMAP L138. However, this board only has UART2 connected to an external connector which this HAL indicates by implementing the CYGINT_HAL_L1XX_UART2 interface. This serial channel is used by RedBoot for communication with the host. If this device is needed by the application, either directly or via the serial driver, then it cannot also be used for RedBoot communication. Another communication channel such as ethernet should be used instead. The serial driver package is loaded automatically when configuring for the Zoom-L138 target.

There is an ethernet driver CYGPKG_DEVS_ETH_ARM_OMAP for the on-chip ethernet device. The platform HAL package is responsible for configuring this generic driver to the hardware. This driver is also loaded automatically when configuring for the Zoom-l138 board.

There is a watchdog driver CYGPKG_DEVICES_WATCHDOG_ARM_OMAP_L1XX. This driver is also loaded automatically when configuring for the board.

There is a driver for the on-chip real-time clock (RTC) at CYGPKG_DEVS_WALLCLOCK_ARM_OMAP_L1XX. This driver is also loaded automatically when configuring for the target.

The OMAP L1XX processor HAL contains a driver for the MultiMedia Card Interface (MMC/SD). This driver is loaded automatically when configuring for this target and allows use of MMC and Secure Digital (SD) flash storage cards within eCos, exported as block devices. Further documentation on the driver may be found in the OMAP L1XX processor HAL documentation.

The platform HAL provides definitions to allow access to devices on the SPI bus. The HAL provides information to the more general OMAP SPI driver (CYGPKG_DEVS_SPI_ARM_OMAP) which in turn provides the underlying implementation for the SPI API layer in the CYGPKG_IO_SPI package. All these packages are automatically loaded when configuring for the board.

Furthermore, the platform HAL package contains support for the SPI NOR flash. The HAL support integrates with the CYGPKG_DEVS_FLASH_SPI_M25PXX package as well as the above SPI packages. That package is automatically loaded when configuring for the target. This driver is capable of supporting the JFFS2 filesystem.

In general, devices (Caches, GPIO, UARTs) are initialized only as far as is necessary for eCos to run. Other devices (RTC, SPI, MMC/SD etc.) are not touched unless the appropriate driver is loaded, although in some cases, the HAL boot sequence will set up the appropriate power control and pin multiplexing configuration.

Tools

The board support is intended to work with GNU tools configured for an arm-eabi target. The original port was undertaken using arm-eabi-gcc version 4.3.2, arm-eabi-gdb version 6.8, and binutils version 2.18.