As applications grow in complexity, the need to fix bugs, add features, and otherwise modify embedded firmware is increasingly critical in end applications. Enabling functionality like this can be easily and inexpensively accomplished through the use of bootloaders.

A bootloader, also referred to as a ROM loader or simply loader, is a small piece of code that resides in the target device's boot-ROM memory that allows the loading and execution of code from an external host. In most cases, a communication peripheral such as Universal Asynchronous Receiver/Transmitter (UART) or Controller Area Network (CAN) is used to load code into the device rather than JTAG, which requires an expensive specialized tool.

Boot Pins are used to configure different boot modes using various peripherals that determine which ROM loader is invoked. In this report, the peripheral used is Serial Communications Interface (SCI, generally referred to as UART). The boot modes that are associated with the boot pins refer to the first instance of the peripheral - for SCI, the boot mode would be associated with SCIA.

C2000 devices partially solve the problem of firmware updates by including some basic loading utilities in ROM. Depending on the device and the communications peripherals present, code can be loaded into on-chip RAM using UART, Serial Peripheral Interface (SPI), Inter-Integrated Circuit (I2C), Ethernet, CAN, and a parallel mode using General Purpose Input/Outputs (GPIOs). A subset of these loaders is present in every C2000 device and they are very easy to use, but they can only load code into RAM. How does one bridge the gap and program their application code into non-volatile memory?

This application report aims to solve this problem by using a flash kernel. Flash kernels have been around for some time, but this document discusses the specifics of the kernels and the host application tool found in C2000Ware. While this implementation is targeted at C2000 devices using the SCI peripheral, the same principles apply to all devices in the C2000 product line and all communications options supported by the ROM loaders. A command line tool is provided to parse and transmit the application image from the host PC (Windows only) to the embedded device.

In summary, application programming to non-volatile memory like flash requires two steps:

1. Use the SCI ROM bootloader to download a flash kernel to RAM.
2. Run the flash kernel in RAM to download the application to flash.