User guide

8
Atmel AVR2054
8390B-AVR-12/11
3. For every valid SREC record the embedded bootloader responds with an ACK
data sequence over the serial interface.
4. In case of any error during loading process, the embedded bootloader sends a
NACK data sequence, then proceeds to (1).
On the PC side, the Bootloader PC tool performs the following actions:
1. The Bootloader PC tool sends a HANDSHAKE_REQ data sequence for 30
seconds with 200ms interval, waiting for a HANDSHAKE_CONF data sequence
between transmissions. Any reply except HANDSHAKE_CONF is ignored.
2. If HANDSHAKE_CONF is received, the PC bootloader starts sending data from
the SREC file via the serial link. Each record of the SREC file is converted to
binary representation before sending.
3. For every record sent the host expects an ACK over the serial link as a response.
If a NACK sequence is received or a timeout occurs, the PC bootloader aborts.
Serial data sequences used between the device and the host while boot loading:
• HANDSHAKE_REQ: 0xB2, 0xA5, 0x65, 0x4B
• HANDSHAKE_CONF: 0x69, 0xD3, 0xD2, 0x26
• ACK: 0x4D, 0x5A, 0x9A, 0xB4
• NACK: 0x2D, 0x59, 0x5A, 0xB2
Figure 3-2 illu
strates the flowchart of the serial bootloader programming algorithm.