User guide

Atmel AVR2054: Serial Bootloader User Guide [APPLICATION NOTE]
8390D−WIRELESS−03/2015
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2. Installation and getting started
Serial bootloader is typically used in the following way:
1. Unpack the package to a folder on the PC hard drive.
2. If embedded bootloader is not present on the target MCU device:
a. Connect JTAG/ISP adapter to the target MCU device.
b. If needed, configure on the MCU device the fuse bits for the corresponding bootloader feature support (see
Section 2.2).
c. Select or build a .hex image of the embedded bootloader with support of required serial interfaces and
feature set. See Section 1.3.2 Precompiled bootloader firmware describing pre-compiled firmware images
and Sections 3.2-3.3 describing how to configure and compile embedded bootloader source code.
d. Program the target MCU with the .hex embedded bootloader image via JTAG/ISP insterface (see Section
3.4). Now the MCU has the embedded bootstrap on it.
3. Connect the MCU with the embedded bootstrap to the host device (for example a PC) via the serial interface
supported in the MCU’s embedded bootstrap (see Section 2.1 Serial interface connections).
4. If a PC is used as the host:
a. If needed install the board- and connection-specific drivers (example VCP, USB, etc.) to get the serial
connection to the connected MCU enumerated properly on the PC (see Section 2.1).
b. Install the Bootloader PC tool from \PC_Bootloader_Setup\. To launch the Bootloader PC tool you will
need to install Java® [14], if it is not installed on your PC.
c. Launch the Bootloader PC tool, specify the connection settings to the target device, the application image in
SREC format, and upload the image to the target MCU (see Section 4.1 for the detailed instructions).
5. If the host is not Atmel PC Bootloader tool:
a. Implement own host application that will be able to upload the .srec images following the serial protocol
supported by the embedded bootloader. See Section 3.5 and 3.6 for protocols description.
b. Perfrorm firmware upload according to own host program algorithm and requirements.
2.1 Serial interface connections
Embedded bootloader can work with USART, SPI, TWI and USB interfaces. The exact set of supported interfaces
depends on a platform and is provided in Section 1.2 while interfaces used by default in precompiled images are given in
Section 1.3.2. MCU pins shall be connected to the host according to the pin assignement of the supported serial
interface described in target MCU’s datasheet.
Several different interfaces and ports can be enabled for bootloader use at the same time. As described in Section 3.5
embedded bootloader will scan them for required handshake packages one after another. Note however that TWI
interfase can be operated only alone.
2.1.1 USART interface
Embedded bootloader supports different USART ports available on the target MCU as listed in Table 1-1. For USART
connection between the MCU and the host is is required to connect only TXD, RXD and GND pins of the corresponding
port. It is the responsibility of the user to ensure proper connection to the host device.
Default port configuration used for UART and hence also in precompiled firmware images is given in Table 2-1.