USB

A bootloader (or code loader) enables convenient updating of device firmware in the field. The term, "bootloader", usually refers to a piece of firmware that resides in program code space on the device and possesses the ability to receive new application firmware through a generic communication channel, eliminating the need for a dedicated programming interface with associated programming circuitry. In other words, a bootloader enables "in-application reprogrammability" via a communication channel. This application note describes the design of a USB bootloader built using the USBXpress Application Programming Interface (API), as well as the modifications necessary to make an existing USBXpress application bootloader-aware. The USBXpress API is described in detail in "AN169: USBXpress Programmer's Guide". 16 pages.

The Universal Serial Bus (USB) has seen enormous success in PC systems and is replacing the older parallel and serial ports. For a standard serial port, the communication is directly performed by the application running on the computer. In order to be Plug-and-Play and Hot-Plug, the USB bus introduces a process that uniquely identifies a device to the Host computer in order for it to learn the capabilities of the device and to load the appropriate driver. This identification process is called the Enumeration process and uses a standard set of commands described in the Chapter 9 of the USB specification, "USB Device Framework". 14 pages.

This document describes the USB bootloader functionalities as well as the USB protocol to efficiently perform operations on the on-chip Flash (EEPROM) memories. Additional information on the AT89C5131 product can be found in the AT89C5131 datasheet and the AT89C5131 errata sheet available on the Atmel web site. The bootloader software package (source code and binary) currently used for production is available from the Atmel web site. 33 pages.

The MAX14578E/MAX14578AE are USB charger detectors compliant with USB Battery Charging Revision 1.1. The USB charger-detection circuitry detects USB standard downstream ports (SDPs), USB charging downstream ports (CDPs), or dedicated charger ports (DCPs), and controls an external lithium-ion (Li+) battery charger. 23 pages.

In the PC world, the RS-232 COM port is about to disappear from most computers (especially from laptops) in the future, replaced by the USB connection. However, many applications still use the RS-232 standard. One solution can be to use the USB bus as it is an RS-232. The advantages are: no need to change the PC application; few hardware and software embedded modifications. This document has two main objectives. The first one is to describe how to migrate from a RS-232 to the USB into the firmware using the Atmel USB RS-232 Virtual COM port library. The second one is to describe how to build a USB <-> RS-232 bridge, using the Atmel library. 9 pages.